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Exported on March 22, 2026 at 02:41 AM

Organism: Bacillus subtilis

Sequence:

MFAKRFKTSLLPLFAGFLLLFHLVLAGPAAASAETANKSNELTAPSIKSGTILHAWNWSFNTLKHNMKDIHDAGYTAIQTSPINQVKEGNQGDKSMSNWYWLYQPTSYQIGNRYLGTEQEFKEMCAAAEEYGIKVIVDAVINHTTSDYAAISNEVKSIPNWTHGNTQIKNWSDRWDVTQNSLLGLYDWNTQNTQVQSYLKRFLDRALNDGADGFRFDAAKHIELPDDGSYGSQFWPNITNTSAEFQYGEILQDSASRDAAYANYMDVTASNYGHSIRSALKNRNLGVSNISHYASDVSADKLVTWVESHDTYANDDEESTWMSDDDIRLGWAVIASRSGSTPLFFSRPEGGGNGVRFPGKSQIGDRGSALFEDQAITAVNRFHNVMAGQPEELSNPNGNNQIFMNQRGSHGVVLANAGSSSVSINTATKLPDGRYDNKAGAGSFQVNDGKLTGTINARSVAVLYPDDIAKAPHVFLENYKTGVTHSFNDQLTITLRADANTTKAVYQINNGPETAFKDGDQFTIGKGDPFGKTYTIMLKGTNSDGVTRTEKYSFVKRDPASAKTIGYQNPNHWSQVNAYIYKHDGSRVIELTGSWPGKPMTKNADGIYTLTLPADTDTTNAKVIFNNGSAQVPGQNQPGFDYVLNGLYNDSGLSGSLPH

Thinking Trace

The architecture begins with IPR017853 (Glycoside hydrolase superfamily, residues 47–354), which frames an N-terminal catalytic core typical of endo-acting α-glycoside hydrolases. Nested within this region is IPR006047 (Glycosyl hydrolase family 13, catalytic domain, residues 50–383) and IPR006046 (Alpha amylase family, residues 99–312). This trio of GH13 signatures defines a classical α-amylase fold that houses the catalytic triad responsible for endohydrolysis of internal α-1,4-glycosidic bonds in starch and related glucans. Immediately downstream, IPR013780 (Glycosyl hydrolase, all-beta superfamily, residues 389–466), together with IPR031319 (Alpha-amylase, C-terminal domain, residues 393–468) and IPR006048 (Alpha-amylase/branching enzyme, C-terminal all beta, residues 396–465), forms the β-sandwich stabilization module that buttresses the catalytic barrel and shapes substrate channels. The C-terminal half then extends into IPR013783 (Immunoglobulin-like fold superfamily, residues 560–658) and IPR031965 (Starch-binding module 26, residues 565–637). This Ig-like appendage is a canonical amylose/amylopectin-tether that increases avidity for polymeric starch and concentrates insoluble granules at the enzyme surface.

This ordered layout—an N-terminal GH13 catalytic engine (IPR006047/IPR006046/IPR017853) followed by a stabilizing all-β C-terminal domain set (IPR013780/IPR031319/IPR006048) and capped with a C-terminal Ig-like starch-binding appendage (IPR013783/IPR031965)—causally dictates endo-acting α-amylase chemistry. The catalytic barrel and triad architecture produce internal scission of α-1,4 linkages, establishing the molecular function formalized as GO:0004556 alpha-amylase activity.

Endo-hydrolysis of starch is the initiating step of extracellular starch depolymerization and nutrient acquisition in Bacillus subtilis. By fragmenting polymeric maltooligosaccharides into soluble products, the enzyme drives the pathway that mobilizes environmental polysaccharides, aligning with GO:0005983 starch catabolic process. The presence of a dedicated starch-binding module 26 and an Ig-like fold explains how the enzyme remains processive on bulky insoluble substrates: the C-terminal appendage increases local substrate concentration and thereby accelerates the catabolic cascade.

The absence of transmembrane motifs and the presence of soluble β-sandwich and Ig-like domains argue for a soluble extracellular enzyme. In Gram-positive bacteria that harvest environmental polysaccharides, such hydrolases are typically secreted and operate outside the cell. Thus, the most parsimonious cellular component is the extracellular region (GO:0005576), consistent with secretion and with the need to attack insoluble starch granules prior to uptake.

Mechanistically, the enzyme likely binds starch via its C-terminal module, positions polymeric substrates in the GH13 catalytic cleft, and executes repeated endo-cleavage to generate maltodextrins. It plausibly cooperates with secreted glucoamylases and maltodextrin transport systems that import and further process its products. Additional transient partnerships with other secreted glycosidases and with cell-surface carbohydrate-capture assemblies would streamline substrate acquisition and channel liberated sugars into central metabolism.

Functional Summary

A secreted endo-acting starch hydrolase from Bacillus subtilis that initiates extracellular starch breakdown by binding insoluble polysaccharide granules and cleaving internal α-1,4 linkages to produce maltodextrins. Its catalytic core is stabilized by a C-terminal β-sandwich and augmented by a distal immunoglobulin-like starch-binding appendage that concentrates substrate and enhances processivity. Operating outside the cell, it fuels nutrient acquisition by priming environmental starch for downstream catabolism and uptake.

UniProt Summary

Alpha-amylase hydrolyzes alpha-1,4-glycosidic bonds of starch and related polysaccharides.

InterPro Domains

• Glycoside hydrolase superfamily (IPR017853, homologous_superfamily) — residues 47-354
• Glycosyl hydrolase family 13, catalytic domain (IPR006047, domain) — residues 50-383
• Alpha amylase (IPR006046, family) — residues 99-312
• Glycosyl hydrolase, all-beta (IPR013780, homologous_superfamily) — residues 389-466
• Alpha-amylase, C-terminal domain (IPR031319, domain) — residues 393-468
• Alpha-amylase/branching enzyme, C-terminal all beta (IPR006048, domain) — residues 396-465
• Immunoglobulin-like fold (IPR013783, homologous_superfamily) — residues 560-658
• Starch-binding module 26 (IPR031965, domain) — residues 565-637

GO Terms

Molecular Function: molecular_function (GO:0003674), catalytic activity (GO:0003824), hydrolase activity (GO:0016787), hydrolase activity, acting on glycosyl bonds (GO:0016798), hydrolase activity, hydrolyzing O-glycosyl compounds (GO:0004553), amylase activity (GO:0016160), alpha-amylase activity (GO:0004556)

Biological Process: biological_process (GO:0008150), metabolic process (GO:0008152), cellular process (GO:0009987), cellular metabolic process (GO:0044237), organic substance metabolic process (GO:0071704), catabolic process (GO:0009056), primary metabolic process (GO:0044238), carbohydrate metabolic process (GO:0005975), organic substance catabolic process (GO:1901575), cellular macromolecule metabolic process (GO:0044260), macromolecule metabolic process (GO:0043170), cellular carbohydrate metabolic process (GO:0044262), cellular catabolic process (GO:0044248), cellular carbohydrate catabolic process (GO:0044275), macromolecule catabolic process (GO:0009057), carbohydrate catabolic process (GO:0016052), cellular polysaccharide metabolic process (GO:0044264), polysaccharide metabolic process (GO:0005976), polysaccharide catabolic process (GO:0000272), glucan metabolic process (GO:0044042), cellular polysaccharide catabolic process (GO:0044247), cellular glucan metabolic process (GO:0006073), starch catabolic process (GO:0005983), glucan catabolic process (GO:0009251), starch metabolic process (GO:0005982)

Cellular Component: cellular_component (GO:0005575), cellular anatomical entity (GO:0110165), extracellular region (GO:0005576)

Generated by BioReason

BioReason Chat Export

Exported on March 22, 2026 at 02:41 AM

Organism: Bacillus subtilis

Sequence:

MFAKRFKTSLLPLFAGFLLLFHLVLAGPAAASAETANKSNELTAPSIKSGTILHAWNWSFNTLKHNMKDIHDAGYTAIQTSPINQVKEGNQGDKSMSNWYWLYQPTSYQIGNRYLGTEQEFKEMCAAAEEYGIKVIVDAVINHTTSDYAAISNEVKSIPNWTHGNTQIKNWSDRWDVTQNSLLGLYDWNTQNTQVQSYLKRFLDRALNDGADGFRFDAAKHIELPDDGSYGSQFWPNITNTSAEFQYGEILQDSASRDAAYANYMDVTASNYGHSIRSALKNRNLGVSNISHYASDVSADKLVTWVESHDTYANDDEESTWMSDDDIRLGWAVIASRSGSTPLFFSRPEGGGNGVRFPGKSQIGDRGSALFEDQAITAVNRFHNVMAGQPEELSNPNGNNQIFMNQRGSHGVVLANAGSSSVSINTATKLPDGRYDNKAGAGSFQVNDGKLTGTINARSVAVLYPDDIAKAPHVFLENYKTGVTHSFNDQLTITLRADANTTKAVYQINNGPETAFKDGDQFTIGKGDPFGKTYTIMLKGTNSDGVTRTEKYSFVKRDPASAKTIGYQNPNHWSQVNAYIYKHDGSRVIELTGSWPGKPMTKNADGIYTLTLPADTDTTNAKVIFNNGSAQVPGQNQPGFDYVLNGLYNDSGLSGSLPH

Thinking Trace

The architecture begins with IPR017853 (Glycoside hydrolase superfamily, residues 47–354), which frames an N-terminal catalytic core typical of endo-acting α-glycoside hydrolases. Nested within this region is IPR006047 (Glycosyl hydrolase family 13, catalytic domain, residues 50–383) and IPR006046 (Alpha amylase family, residues 99–312). This trio of GH13 signatures defines a classical α-amylase fold that houses the catalytic triad responsible for endohydrolysis of internal α-1,4-glycosidic bonds in starch and related glucans. Immediately downstream, IPR013780 (Glycosyl hydrolase, all-beta superfamily, residues 389–466), together with IPR031319 (Alpha-amylase, C-terminal domain, residues 393–468) and IPR006048 (Alpha-amylase/branching enzyme, C-terminal all beta, residues 396–465), forms the β-sandwich stabilization module that buttresses the catalytic barrel and shapes substrate channels. The C-terminal half then extends into IPR013783 (Immunoglobulin-like fold superfamily, residues 560–658) and IPR031965 (Starch-binding module 26, residues 565–637). This Ig-like appendage is a canonical amylose/amylopectin-tether that increases avidity for polymeric starch and concentrates insoluble granules at the enzyme surface.

This ordered layout—an N-terminal GH13 catalytic engine (IPR006047/IPR006046/IPR017853) followed by a stabilizing all-β C-terminal domain set (IPR013780/IPR031319/IPR006048) and capped with a C-terminal Ig-like starch-binding appendage (IPR013783/IPR031965)—causally dictates endo-acting α-amylase chemistry. The catalytic barrel and triad architecture produce internal scission of α-1,4 linkages, establishing the molecular function formalized as GO:0004556 alpha-amylase activity.

Endo-hydrolysis of starch is the initiating step of extracellular starch depolymerization and nutrient acquisition in Bacillus subtilis. By fragmenting polymeric maltooligosaccharides into soluble products, the enzyme drives the pathway that mobilizes environmental polysaccharides, aligning with GO:0005983 starch catabolic process. The presence of a dedicated starch-binding module 26 and an Ig-like fold explains how the enzyme remains processive on bulky insoluble substrates: the C-terminal appendage increases local substrate concentration and thereby accelerates the catabolic cascade.

The absence of transmembrane motifs and the presence of soluble β-sandwich and Ig-like domains argue for a soluble extracellular enzyme. In Gram-positive bacteria that harvest environmental polysaccharides, such hydrolases are typically secreted and operate outside the cell. Thus, the most parsimonious cellular component is the extracellular region (GO:0005576), consistent with secretion and with the need to attack insoluble starch granules prior to uptake.

Mechanistically, the enzyme likely binds starch via its C-terminal module, positions polymeric substrates in the GH13 catalytic cleft, and executes repeated endo-cleavage to generate maltodextrins. It plausibly cooperates with secreted glucoamylases and maltodextrin transport systems that import and further process its products. Additional transient partnerships with other secreted glycosidases and with cell-surface carbohydrate-capture assemblies would streamline substrate acquisition and channel liberated sugars into central metabolism.

Functional Summary

A secreted endo-acting starch hydrolase from Bacillus subtilis that initiates extracellular starch breakdown by binding insoluble polysaccharide granules and cleaving internal α-1,4 linkages to produce maltodextrins. Its catalytic core is stabilized by a C-terminal β-sandwich and augmented by a distal immunoglobulin-like starch-binding appendage that concentrates substrate and enhances processivity. Operating outside the cell, it fuels nutrient acquisition by priming environmental starch for downstream catabolism and uptake.

UniProt Summary

Alpha-amylase hydrolyzes alpha-1,4-glycosidic bonds of starch and related polysaccharides.

InterPro Domains

• Glycoside hydrolase superfamily (IPR017853, homologous_superfamily) — residues 47-354
• Glycosyl hydrolase family 13, catalytic domain (IPR006047, domain) — residues 50-383
• Alpha amylase (IPR006046, family) — residues 99-312
• Glycosyl hydrolase, all-beta (IPR013780, homologous_superfamily) — residues 389-466
• Alpha-amylase, C-terminal domain (IPR031319, domain) — residues 393-468
• Alpha-amylase/branching enzyme, C-terminal all beta (IPR006048, domain) — residues 396-465
• Immunoglobulin-like fold (IPR013783, homologous_superfamily) — residues 560-658
• Starch-binding module 26 (IPR031965, domain) — residues 565-637

GO Terms

Molecular Function: molecular_function (GO:0003674), catalytic activity (GO:0003824), hydrolase activity (GO:0016787), hydrolase activity, acting on glycosyl bonds (GO:0016798), hydrolase activity, hydrolyzing O-glycosyl compounds (GO:0004553), amylase activity (GO:0016160), alpha-amylase activity (GO:0004556)

Biological Process: biological_process (GO:0008150), metabolic process (GO:0008152), cellular process (GO:0009987), cellular metabolic process (GO:0044237), organic substance metabolic process (GO:0071704), catabolic process (GO:0009056), primary metabolic process (GO:0044238), carbohydrate metabolic process (GO:0005975), organic substance catabolic process (GO:1901575), cellular macromolecule metabolic process (GO:0044260), macromolecule metabolic process (GO:0043170), cellular carbohydrate metabolic process (GO:0044262), cellular catabolic process (GO:0044248), cellular carbohydrate catabolic process (GO:0044275), macromolecule catabolic process (GO:0009057), carbohydrate catabolic process (GO:0016052), cellular polysaccharide metabolic process (GO:0044264), polysaccharide metabolic process (GO:0005976), polysaccharide catabolic process (GO:0000272), glucan metabolic process (GO:0044042), cellular polysaccharide catabolic process (GO:0044247), cellular glucan metabolic process (GO:0006073), starch catabolic process (GO:0005983), glucan catabolic process (GO:0009251), starch metabolic process (GO:0005982)

Cellular Component: cellular_component (GO:0005575), cellular anatomical entity (GO:0110165), extracellular region (GO:0005576)

Generated by BioReason

provider: falcon
model: Edison Scientific Literature
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template_file: templates/gene_research_go_focused.md
template_variables:
organism: BACSU
gene_id: amyE
gene_symbol: amyE
uniprot_accession: P00691
protein_description: 'RecName: Full=Alpha-amylase; EC=3.2.1.1 {ECO:0000250|UniProtKB:P06278};
AltName: Full=1,4-alpha-D-glucan glucanohydrolase; Flags: Precursor;'
gene_info: Name=amyE; Synonyms=amyA; OrderedLocusNames=BSU03040;
organism_full: Bacillus subtilis (strain 168).
protein_family: Belongs to the glycosyl hydrolase 13 family. .
protein_domains: A-amylase/branching_C. (IPR006048); A-amylase_C. (IPR031319); Alpha_amylase.
(IPR006046); CBM26. (IPR031965); Glyco_hydro_13_cat_dom. (IPR006047)
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Question

Gene Research for Functional Annotation

⚠️ CRITICAL: Gene/Protein Identification Context

BEFORE YOU BEGIN RESEARCH: You MUST verify you are researching the CORRECT gene/protein. Gene symbols can be ambiguous, especially for less well-characterized genes from non-model organisms.

Target Gene/Protein Identity (from UniProt):

• UniProt Accession: P00691
• Protein Description: RecName: Full=Alpha-amylase; EC=3.2.1.1 {ECO:0000250|UniProtKB:P06278}; AltName: Full=1,4-alpha-D-glucan glucanohydrolase; Flags: Precursor;
• Gene Information: Name=amyE; Synonyms=amyA; OrderedLocusNames=BSU03040;
• Organism (full): Bacillus subtilis (strain 168).
• Protein Family: Belongs to the glycosyl hydrolase 13 family. .
• Key Domains: A-amylase/branching_C. (IPR006048); A-amylase_C. (IPR031319); Alpha_amylase. (IPR006046); CBM26. (IPR031965); Glyco_hydro_13_cat_dom. (IPR006047)

MANDATORY VERIFICATION STEPS:

1. Check if the gene symbol "amyE" matches the protein description above
2. Verify the organism is correct: Bacillus subtilis (strain 168).
3. Check if protein family/domains align with what you find in literature
4. If you find literature for a DIFFERENT gene with the same or similar symbol, STOP

If Gene Symbol is Ambiguous or You Cannot Find Relevant Literature:

DO NOT PROCEED WITH RESEARCH ON A DIFFERENT GENE. Instead:
- State clearly: "The gene symbol 'amyE' is ambiguous or literature is limited for this specific protein"
- Explain what you found (e.g., "Found extensive literature on a different gene with the same symbol in a different organism")
- Describe the protein based ONLY on the UniProt information provided above
- Suggest that the protein function can be inferred from domain/family information

Research Target:

Please provide a comprehensive research report on the gene amyE (gene ID: amyE, UniProt: P00691) in BACSU.

The research report should be a detailed narrative explaining the function, biological processes, and localization of the gene product. Citations should be given for all claims.

You should prioritize authoritative reviews and primary scientific literature when conducting research. You can supplement
this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.

We are specifically interested in the primary function of the gene - for enzymes, what reaction is catalyzed, and what is the substrate specificity? For transporters, what is the substrate? For structural proteins or adapters, what is the broader structural role? For signaling molecules, what is the role in the pathway.

We are interested in where in or outside the cell the gene product carries out its function.

We are also interested in the signaling or biochemical pathways in which the gene functions. We are less interested in broad pleiotropic effects, except where these elucidate the precise role.

Include evidence where possible. We are interested in both experimental evidence as well as inference from structure, evolution, or bioinformatic analysis. Precise studies should be prioritized over high-throughput, where available.

Output

Question: You are an expert researcher providing comprehensive, well-cited information.

Provide detailed information focusing on:
1. Key concepts and definitions with current understanding
2. Recent developments and latest research (prioritize 2023-2024 sources)
3. Current applications and real-world implementations
4. Expert opinions and analysis from authoritative sources
5. Relevant statistics and data from recent studies

Format as a comprehensive research report with proper citations. Include URLs and publication dates where available.
Always prioritize recent, authoritative sources and provide specific citations for all major claims.

Gene Research for Functional Annotation

⚠️ CRITICAL: Gene/Protein Identification Context

BEFORE YOU BEGIN RESEARCH: You MUST verify you are researching the CORRECT gene/protein. Gene symbols can be ambiguous, especially for less well-characterized genes from non-model organisms.

Target Gene/Protein Identity (from UniProt):

• UniProt Accession: P00691
• Protein Description: RecName: Full=Alpha-amylase; EC=3.2.1.1 {ECO:0000250|UniProtKB:P06278}; AltName: Full=1,4-alpha-D-glucan glucanohydrolase; Flags: Precursor;
• Gene Information: Name=amyE; Synonyms=amyA; OrderedLocusNames=BSU03040;
• Organism (full): Bacillus subtilis (strain 168).
• Protein Family: Belongs to the glycosyl hydrolase 13 family. .
• Key Domains: A-amylase/branching_C. (IPR006048); A-amylase_C. (IPR031319); Alpha_amylase. (IPR006046); CBM26. (IPR031965); Glyco_hydro_13_cat_dom. (IPR006047)

MANDATORY VERIFICATION STEPS:

1. Check if the gene symbol "amyE" matches the protein description above
2. Verify the organism is correct: Bacillus subtilis (strain 168).
3. Check if protein family/domains align with what you find in literature
4. If you find literature for a DIFFERENT gene with the same or similar symbol, STOP

If Gene Symbol is Ambiguous or You Cannot Find Relevant Literature:

DO NOT PROCEED WITH RESEARCH ON A DIFFERENT GENE. Instead:
- State clearly: "The gene symbol 'amyE' is ambiguous or literature is limited for this specific protein"
- Explain what you found (e.g., "Found extensive literature on a different gene with the same symbol in a different organism")
- Describe the protein based ONLY on the UniProt information provided above
- Suggest that the protein function can be inferred from domain/family information

Research Target:

Please provide a comprehensive research report on the gene amyE (gene ID: amyE, UniProt: P00691) in BACSU.

The research report should be a detailed narrative explaining the function, biological processes, and localization of the gene product. Citations should be given for all claims.

You should prioritize authoritative reviews and primary scientific literature when conducting research. You can supplement
this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.

We are specifically interested in the primary function of the gene - for enzymes, what reaction is catalyzed, and what is the substrate specificity? For transporters, what is the substrate? For structural proteins or adapters, what is the broader structural role? For signaling molecules, what is the role in the pathway.

We are interested in where in or outside the cell the gene product carries out its function.

We are also interested in the signaling or biochemical pathways in which the gene functions. We are less interested in broad pleiotropic effects, except where these elucidate the precise role.

Include evidence where possible. We are interested in both experimental evidence as well as inference from structure, evolution, or bioinformatic analysis. Precise studies should be prioritized over high-throughput, where available.

Plan status update
- Objective 1 (verify identity) completed: amyE encodes Bacillus subtilis alpha-amylase (UniProt P00691), GH13 family; matches organism B. subtilis strain 168; domain annotations align with GH13 A/B catalytic domain, C-terminal Amy_C domain, and a starch-binding CBM26 by homology. (paloyan2024molecularcloningand pages 5-6, paloyan2024molecularcloningand pages 3-5)
- Objectives 2–4 (recent literature, evidence extraction, expert synthesis) completed using 2023–2024 sources listed below.
- Objective 5 (artifact) created and embedded below.
- Objective 6 (final report) submitted here.

Comprehensive research report: amyE (UniProt P00691), Bacillus subtilis 168

1) Identity verification and key definitions
- Gene/protein identity: amyE encodes the secreted alpha-amylase of Bacillus subtilis (strain 168), a glycoside hydrolase family 13 (GH13) enzyme that hydrolyzes internal α-1,4-glycosidic linkages in starch and related α-glucans (retaining mechanism). This aligns with UniProt P00691 and the target organism. (paloyan2024molecularcloningand pages 5-6, jaiswal2024thermostableαamylasesand pages 4-5)
- Family/domains: GH13 alpha-amylases possess a catalytic (β/α)8 barrel (domain A) with an inserted domain B and a C-terminal β-sandwich (Amy_C). Many Bacillus enzymes also carry carbohydrate-binding modules (CBMs); homology-based analyses of B. subtilis α-amylases closely related to AmyE indicate a C-terminal CBM26 module. (paloyan2024molecularcloningand pages 3-5, paloyan2024molecularcloningand pages 5-6)

2) Primary biochemical function and catalytic mechanism
- Reaction: Endo-acting hydrolysis of (1→4)-α-D-glucan linkages in starch and maltooligosaccharides, generating mainly maltose and glucose under many assay conditions; cyclodextrins and branched substrates are also hydrolyzed at lower rates in representative B. subtilis enzymes. (paloyan2024molecularcloningand pages 5-6, paloyan2024molecularcloningand pages 6-8)
- Mechanism: GH13 enzymes use a double-displacement α-retaining mechanism with a catalytic nucleophile (Asp), a general acid/base (Glu), and a transition-state stabilizing Asp; all embedded in conserved GH13 sequence motifs within the (β/α)8 scaffold. Expert reviews and recent syntheses reaffirm these features. (jaiswal2024thermostableαamylasesand pages 4-5)

3) Substrate specificity and product profile
- Substrate spectrum: Representative B. subtilis α-amylase highly similar to AmyE (97.4% identity to P00691) shows activity on starches with preference potato > wheat > corn > rice; it hydrolyzes amylose/amylopectin more weakly than soluble starch, and acts on γ- and β-cyclodextrins at lower rates. Products from common starches are predominantly maltose and glucose. These data are informative for AmyE due to near-identity and shared GH13 architecture. (paloyan2024molecularcloningand pages 5-6, paloyan2024molecularcloningand pages 6-8)

4) Domain architecture and sequence features
- Signal peptide: A canonical N-terminal signal peptide directs Sec-dependent secretion; in a closely related B. subtilis α-amylase, cleavage is between residues 31–32. During extracellular maturation, the C-terminus can be processed, consistent with the modular C-terminal domain and/or CBM removal in secreted forms. (paloyan2024molecularcloningand pages 3-5, paloyan2024molecularcloningand pages 6-8)
- Catalytic core: The A/B domains constitute the GH13 catalytic machinery; the C-terminal Amy_C domain and optional CBM26 contribute to stability and raw-starch binding. (paloyan2024molecularcloningand pages 3-5, paloyan2024molecularcloningand pages 5-6)

5) Cellular localization and secretion pathway
- Secretion route: AmyE is exported via the Sec pathway. Strach et al. (2023) directly visualized AmyE-mCherry and observed discrete, persistent “secretion zones” within the Gram-positive cell wall; these zones appear primarily at the transition to stationary phase and correspond to surface-detectable amylase activity. SecA/SecDF dynamics at the membrane support Sec-mediated translocation followed by slow diffusion through the peptidoglycan mesh. (strach2023proteinsecretionzones pages 1-2)
- Quantitative secretion dynamics: In B. subtilis, cells with visible AmyE secretion puncta increased from ~4–5% in mid-exponential phase to ~23% at transition and ~19–34% in stationary phase (strain- and condition-dependent). These data substantiate extracellular localization and phase-dependent secretion heterogeneity. (strach2023proteinsecretionzones pages 2-3)

6) Regulation of expression (promoters; growth phase)
- Native/engineering promoters: Put et al. (2024) catalog promoter resources in Bacillus, including Pamy (amyE promoter, described as intermediate strength) and inducible promoters (PxylA, Pgrac, Pspank/Pspank-hy, Pglv, PsacB). Signal peptides including SPamyE are used as secretion tags in expression cassettes. These parts underpin controlled expression of endogenous and heterologous proteins. (put2024bacillussubtilisas pages 20-21, put2024bacillussubtilisas pages 21-22)
- Growth phase: Secretion zones and extracellular activity of AmyE become prominent at the transition to stationary phase in laboratory overexpression, suggesting physiological coupling between secretion capacity and growth phase. (strach2023proteinsecretionzones pages 1-2)

7) Biochemical properties and quantitative data (representative for AmyE homologs)
- Optima: A B. subtilis α-amylase 97% identical to AmyE shows temperature optimum ~65 °C and pH optimum ~6.0; retains substantial activity across 55–65 °C and tolerates mildly acidic pH in the wild-type secreted form. (paloyan2024molecularcloningand pages 5-6, paloyan2024molecularcloningand pages 6-8)
- Specific activity: Recombinant enzyme specific activity ~1,280 U/mg under standard assay (65 °C, pH 6.0; DNS assay). (paloyan2024molecularcloningand pages 5-6)
- Metal/detergent effects: Activity is EDTA-tolerant in that study; strong inhibition by Cu2+ (>90%) and partial inhibition by Fe2+/Zn2+; SDS (1%) ~80% inhibition, whereas nonionic detergents had minor effects. (paloyan2024molecularcloningand pages 8-10)
- Processing: In the secreted native form, apparent molecular weight can be lower than the full precursor, consistent with signal peptide removal and possible C-terminal trimming. (paloyan2024molecularcloningand pages 6-8)

8) Current applications and real-world implementations
- Industrial enzyme: Bacillus α-amylases are industrial workhorses in starch processing (baking, brewing, syrups); recent studies of B. subtilis enzymes highlight raw-starch activity and process-relevant stability profiles. (paloyan2024molecularcloningand pages 8-10)
- Secretion host and parts: Bacillus subtilis is widely used as a secretion host; engineered strains and toolkits leverage SPamyE for secretion and a palette of promoters (Pamy, Pveg, P43, PxylA, Pgrac, etc.) for tunable expression. (put2024bacillussubtilisas pages 20-21, put2024bacillussubtilisas pages 21-22)
- Neutral chromosomal integration site: The amyE locus is a standard “neutral” integration site in B. subtilis 168. For example, Pérez‑Lorente et al. (2023) integrated constructs with pDR111 at amyE (selected by spectinomycin), demonstrating contemporary use in 2023 work. (perezlorente2023sporulationactivatedvia pages 12-13)
- Secretion optimization: Reviews emphasize extracellular protease-deficient strains and genome reductions to stabilize secreted products; engineered backgrounds include sequential knockouts (e.g., nprE, aprE, amyE) to reduce proteolysis and modulate background enzymes for improved heterologous protein recovery. (liu2025engineeringbacillussubtilis pages 2-4)

9) Expert opinions and analysis (authoritative sources, 2023–2024)
- GH13 mechanism and engineering: Contemporary reviews affirm the canonical GH13 retaining mechanism and highlight protein engineering to tune thermostability, Ca2+ dependence, and catalytic traits—principles applicable to AmyE. (jaiswal2024thermostableαamylasesand pages 4-5)
- Secretion biology in Gram-positives: Strach et al. (2023) provide an updated, single-molecule perspective on the spatial organization of secretion through the thick cell wall, relevant for AmyE localization and for optimizing secretion of heterologous proteins fused to SPamyE. (strach2023proteinsecretionzones pages 1-2)
- Bacillus as expression chassis: Put et al. (2024) consolidate modern promoter/toolbox options, secretion capacity considerations, and strategies for heterologous pathway expression—situating amyE (as a locus and signal peptide source) within current best practices. (put2024bacillussubtilisas pages 20-21, put2024bacillussubtilisas pages 21-22)

10) Consolidated fact table
| Aspect | Key Findings | Source IDs |
|---|---|---|
| Identity verification | amyE encodes B. subtilis alpha-amylase (UniProt P00691), member GH13; CBM26-like C‑terminal module predicted by homology; ~658 aa precursor with signal peptide | (paloyan2024molecularcloningand pages 5-6, paloyan2024molecularcloningand pages 10-14) |
| Catalytic mechanism | GH13-family retaining double-displacement mechanism (Asp/Glu catalytic pair; classical GH13 active-site motifs) | (jaiswal2024thermostableαamylasesand pages 4-5, paloyan2024molecularcloningand pages 8-10) |
| Substrate specificity & products | Higher activity on potato > wheat > corn > rice starch; acts on amylose/amylopectin and cyclodextrins (lower); main hydrolysis products: glucose and maltose | (paloyan2024molecularcloningand pages 5-6, paloyan2024molecularcloningand pages 6-8) |
| Biochemical optima & stability | Temperature optimum ≈65°C; pH optimum ≈6.0; Ca2+ often stabilizing/EDTA-tolerant in some isolates; inhibited strongly by Cu2+ (>90%) and partly by Fe2+/Zn2+; SDS strongly inhibitory (~80%) | (paloyan2024molecularcloningand pages 5-6, paloyan2024molecularcloningand pages 8-10) |
| Domain architecture | Typical GH13 A/B catalytic region plus C-terminal ß-sheet/Amy_C domain; predicted CBM26 at C-terminus in homologs; N-terminal signal peptide cleaved ~residue 31 | (paloyan2024molecularcloningand pages 3-5, paloyan2024molecularcloningand pages 5-6) |
| Secretion / localization | N-terminal signal peptide required for Sec-mediated membrane translocation (SecA/SecDF/PrsA implicated); secreted extracellularly through cell wall via discrete "secretion zones" appearing at transition/stationary phase | (strach2023proteinsecretionzones pages 2-3, strach2023proteinsecretionzones pages 1-2) |
| Secretion tags & promoters | AmyE signal peptide (SPamyE) used as secretion tag; Pamy listed among promoters ("Intermediate"); many constitutive/inducible promoters (PxylA, Pgrac, Pspank, etc.) used for heterologous expression | (put2024bacillussubtilisas pages 20-21, put2024bacillussubtilisas pages 21-22) |
| Neutral integration site | amyE locus commonly used as a neutral chromosomal integration site for insertions (e.g., pDR111 replacement of amyE in B. subtilis 168) | (perezlorente2023sporulationactivatedvia pages 12-13) |
| Industrial / synthetic-biology uses | B. subtilis is a high-secretion host for enzymes/NPs; protease-deficient and genome-reduced strains improve heterologous protein stability; amyE manipulations used in strain engineering | (put2024bacillussubtilisas pages 20-21, liu2025engineeringbacillussubtilis pages 2-4) |
| Quantitative examples | Recombinant Bacillus amylase examples: specific activity ~1,200–1,280 U/mg at 65°C/pH6; Cu2+ causes >90% inhibition; SDS (1%) ~80% inhibition; fraction of cells showing secretion zones: ~4–5% (mid‑exp) → ~19–34% (transition/stationary) | (paloyan2024molecularcloningand pages 10-14, strach2023proteinsecretionzones pages 2-3) |

Table: Compact, sourced summary of Bacillus subtilis amyE (UniProt P00691) covering identity, mechanism, substrates, domains, secretion, genetic use of the amyE locus, and representative quantitative measurements.

Citations (URLs and publication dates)
- Strach et al., 2023, BMC Biology (Oct 2023). Protein secretion zones during overexpression of amylase within the Gram-positive cell wall. https://doi.org/10.1186/s12915-023-01684-1 (strach2023proteinsecretionzones pages 1-2, strach2023proteinsecretionzones pages 2-3)
- Paloyan et al., 2024, Research Square preprint (Mar 2024). Molecular Cloning and Biochemical Characterization of a novel thermostable α-amylase of Bacillus subtilis MDC 3500. https://doi.org/10.21203/rs.3.rs-4103518/v1 (paloyan2024molecularcloningand pages 5-6, paloyan2024molecularcloningand pages 6-8, paloyan2024molecularcloningand pages 8-10, paloyan2024molecularcloningand pages 3-5, paloyan2024molecularcloningand pages 10-14)
- Jaiswal & Jaiswal, 2024, Processes (Jun 2024). Thermostable α-Amylases and Laccases: Paving the Way for Sustainable Industrial Applications. https://doi.org/10.3390/pr12071341 (jaiswal2024thermostableαamylasesand pages 4-5)
- Pérez‑Lorente et al., 2023, Microbiology Spectrum (Apr 2023). Sporulation Activated via σW Protects Bacillus from a Tse1 T6SS Effector. https://doi.org/10.1128/spectrum.05045-22 (perezlorente2023sporulationactivatedvia pages 12-13)
- Put et al., 2024, Nat. Prod. Rep. (Mar 2024). Bacillus subtilis as a host for natural product discovery and engineering of biosynthetic gene clusters. https://doi.org/10.1039/d3np00065f (put2024bacillussubtilisas pages 20-21, put2024bacillussubtilisas pages 21-22, put2024bacillussubtilisas pages 29-30, put2024bacillussubtilisas pages 19-20, put2024bacillussubtilisas pages 6-7)
- Liu & Yu, 2025, Microbial Cell Factories (Aug 2025; context on secretion/protease mutants and promoter engineering). Engineering Bacillus subtilis for high-value bioproduction. https://doi.org/10.1186/s12934-025-02818-6 (liu2025engineeringbacillussubtilis pages 2-4, liu2025engineeringbacillussubtilis pages 7-9, liu2025engineeringbacillussubtilis pages 4-6)

Notes and limitations
- Some quantitative biochemical parameters (Km, kcat) and catalytic-residue numbering for P00691 in strain 168 were not reported in the 2023–2024 sources retrieved here; representative values from a near-identical B. subtilis enzyme (97.4% identity) are provided with explicit attribution and should be interpreted accordingly. Additional targeted kinetic studies of AmyE (P00691) would refine these parameters. (paloyan2024molecularcloningand pages 5-6, paloyan2024molecularcloningand pages 10-14)

References

1. (paloyan2024molecularcloningand pages 5-6): Ani Paloyan, Tigran Soghomonyan, Lev Khoyetsyan, Lusine Melkonyan, Tamara Davidyan, Anna Mkhitaryan, Valeri Valeri Bagiyan, and Artur Hambardzumyan. Molecular cloning and biochemical characterization of a novel thermostable α-amylase of bacillus subtilis mdc 3500 isolated from acidic soils in armenia. Mar 2024. URL: https://doi.org/10.21203/rs.3.rs-4103518/v1, doi:10.21203/rs.3.rs-4103518/v1.

2. (paloyan2024molecularcloningand pages 3-5): Ani Paloyan, Tigran Soghomonyan, Lev Khoyetsyan, Lusine Melkonyan, Tamara Davidyan, Anna Mkhitaryan, Valeri Valeri Bagiyan, and Artur Hambardzumyan. Molecular cloning and biochemical characterization of a novel thermostable α-amylase of bacillus subtilis mdc 3500 isolated from acidic soils in armenia. Mar 2024. URL: https://doi.org/10.21203/rs.3.rs-4103518/v1, doi:10.21203/rs.3.rs-4103518/v1.

3. (jaiswal2024thermostableαamylasesand pages 4-5): Nivedita Jaiswal and Pundrik Jaiswal. Thermostable α-amylases and laccases: paving the way for sustainable industrial applications. Processes, Jun 2024. URL: https://doi.org/10.3390/pr12071341, doi:10.3390/pr12071341. This article has 22 citations and is from a poor quality or predatory journal.

4. (paloyan2024molecularcloningand pages 6-8): Ani Paloyan, Tigran Soghomonyan, Lev Khoyetsyan, Lusine Melkonyan, Tamara Davidyan, Anna Mkhitaryan, Valeri Valeri Bagiyan, and Artur Hambardzumyan. Molecular cloning and biochemical characterization of a novel thermostable α-amylase of bacillus subtilis mdc 3500 isolated from acidic soils in armenia. Mar 2024. URL: https://doi.org/10.21203/rs.3.rs-4103518/v1, doi:10.21203/rs.3.rs-4103518/v1.

5. (strach2023proteinsecretionzones pages 1-2): Manuel Strach, Felicitas Koch, Svenja Fiedler, Klaus Liebeton, and Peter L. Graumann. Protein secretion zones during overexpression of amylase within the gram-positive cell wall. BMC Biology, Oct 2023. URL: https://doi.org/10.1186/s12915-023-01684-1, doi:10.1186/s12915-023-01684-1. This article has 10 citations and is from a domain leading peer-reviewed journal.

6. (strach2023proteinsecretionzones pages 2-3): Manuel Strach, Felicitas Koch, Svenja Fiedler, Klaus Liebeton, and Peter L. Graumann. Protein secretion zones during overexpression of amylase within the gram-positive cell wall. BMC Biology, Oct 2023. URL: https://doi.org/10.1186/s12915-023-01684-1, doi:10.1186/s12915-023-01684-1. This article has 10 citations and is from a domain leading peer-reviewed journal.

7. (put2024bacillussubtilisas pages 20-21): Hanne Put, Hans Gerstmans, Hanne Vande Capelle, Maarten Fauvart, Jan Michiels, and Joleen Masschelein. Bacillus subtilis as a host for natural product discovery and engineering of biosynthetic gene clusters. Natural product reports, 41:1113-1151, Mar 2024. URL: https://doi.org/10.1039/d3np00065f, doi:10.1039/d3np00065f. This article has 38 citations and is from a peer-reviewed journal.

8. (put2024bacillussubtilisas pages 21-22): Hanne Put, Hans Gerstmans, Hanne Vande Capelle, Maarten Fauvart, Jan Michiels, and Joleen Masschelein. Bacillus subtilis as a host for natural product discovery and engineering of biosynthetic gene clusters. Natural product reports, 41:1113-1151, Mar 2024. URL: https://doi.org/10.1039/d3np00065f, doi:10.1039/d3np00065f. This article has 38 citations and is from a peer-reviewed journal.

9. (paloyan2024molecularcloningand pages 8-10): Ani Paloyan, Tigran Soghomonyan, Lev Khoyetsyan, Lusine Melkonyan, Tamara Davidyan, Anna Mkhitaryan, Valeri Valeri Bagiyan, and Artur Hambardzumyan. Molecular cloning and biochemical characterization of a novel thermostable α-amylase of bacillus subtilis mdc 3500 isolated from acidic soils in armenia. Mar 2024. URL: https://doi.org/10.21203/rs.3.rs-4103518/v1, doi:10.21203/rs.3.rs-4103518/v1.

10. (perezlorente2023sporulationactivatedvia pages 12-13): Alicia I. Pérez-Lorente, Carlos Molina-Santiago, Antonio de Vicente, and Diego Romero. Sporulation activated via σ ^w protects bacillus from a tse1 peptidoglycan hydrolase type vi secretion system effector. Microbiology Spectrum, Apr 2023. URL: https://doi.org/10.1128/spectrum.05045-22, doi:10.1128/spectrum.05045-22. This article has 17 citations and is from a domain leading peer-reviewed journal.

11. (liu2025engineeringbacillussubtilis pages 2-4): Zi-Yan Liu and Xiao-Zheng Yu. Engineering bacillus subtilis for high-value bioproduction: recent advances and applications. Microbial Cell Factories, Aug 2025. URL: https://doi.org/10.1186/s12934-025-02818-6, doi:10.1186/s12934-025-02818-6. This article has 6 citations and is from a peer-reviewed journal.

12. (paloyan2024molecularcloningand pages 10-14): Ani Paloyan, Tigran Soghomonyan, Lev Khoyetsyan, Lusine Melkonyan, Tamara Davidyan, Anna Mkhitaryan, Valeri Valeri Bagiyan, and Artur Hambardzumyan. Molecular cloning and biochemical characterization of a novel thermostable α-amylase of bacillus subtilis mdc 3500 isolated from acidic soils in armenia. Mar 2024. URL: https://doi.org/10.21203/rs.3.rs-4103518/v1, doi:10.21203/rs.3.rs-4103518/v1.

13. (put2024bacillussubtilisas pages 29-30): Hanne Put, Hans Gerstmans, Hanne Vande Capelle, Maarten Fauvart, Jan Michiels, and Joleen Masschelein. Bacillus subtilis as a host for natural product discovery and engineering of biosynthetic gene clusters. Natural product reports, 41:1113-1151, Mar 2024. URL: https://doi.org/10.1039/d3np00065f, doi:10.1039/d3np00065f. This article has 38 citations and is from a peer-reviewed journal.

14. (put2024bacillussubtilisas pages 19-20): Hanne Put, Hans Gerstmans, Hanne Vande Capelle, Maarten Fauvart, Jan Michiels, and Joleen Masschelein. Bacillus subtilis as a host for natural product discovery and engineering of biosynthetic gene clusters. Natural product reports, 41:1113-1151, Mar 2024. URL: https://doi.org/10.1039/d3np00065f, doi:10.1039/d3np00065f. This article has 38 citations and is from a peer-reviewed journal.

15. (put2024bacillussubtilisas pages 6-7): Hanne Put, Hans Gerstmans, Hanne Vande Capelle, Maarten Fauvart, Jan Michiels, and Joleen Masschelein. Bacillus subtilis as a host for natural product discovery and engineering of biosynthetic gene clusters. Natural product reports, 41:1113-1151, Mar 2024. URL: https://doi.org/10.1039/d3np00065f, doi:10.1039/d3np00065f. This article has 38 citations and is from a peer-reviewed journal.

16. (liu2025engineeringbacillussubtilis pages 7-9): Zi-Yan Liu and Xiao-Zheng Yu. Engineering bacillus subtilis for high-value bioproduction: recent advances and applications. Microbial Cell Factories, Aug 2025. URL: https://doi.org/10.1186/s12934-025-02818-6, doi:10.1186/s12934-025-02818-6. This article has 6 citations and is from a peer-reviewed journal.

17. (liu2025engineeringbacillussubtilis pages 4-6): Zi-Yan Liu and Xiao-Zheng Yu. Engineering bacillus subtilis for high-value bioproduction: recent advances and applications. Microbial Cell Factories, Aug 2025. URL: https://doi.org/10.1186/s12934-025-02818-6, doi:10.1186/s12934-025-02818-6. This article has 6 citations and is from a peer-reviewed journal.

Citations

1. strach2023proteinsecretionzones pages 1-2
2. strach2023proteinsecretionzones pages 2-3
3. paloyan2024molecularcloningand pages 5-6
4. paloyan2024molecularcloningand pages 8-10
5. paloyan2024molecularcloningand pages 6-8
6. perezlorente2023sporulationactivatedvia pages 12-13
7. liu2025engineeringbacillussubtilis pages 2-4
8. paloyan2024molecularcloningand pages 3-5
9. put2024bacillussubtilisas pages 20-21
10. put2024bacillussubtilisas pages 21-22
11. paloyan2024molecularcloningand pages 10-14
12. put2024bacillussubtilisas pages 29-30
13. put2024bacillussubtilisas pages 19-20
14. put2024bacillussubtilisas pages 6-7
15. liu2025engineeringbacillussubtilis pages 7-9
16. liu2025engineeringbacillussubtilis pages 4-6
17. https://doi.org/10.1186/s12915-023-01684-1
18. https://doi.org/10.21203/rs.3.rs-4103518/v1
19. https://doi.org/10.3390/pr12071341
20. https://doi.org/10.1128/spectrum.05045-22
21. https://doi.org/10.1039/d3np00065f
22. https://doi.org/10.1186/s12934-025-02818-6
23. https://doi.org/10.21203/rs.3.rs-4103518/v1,
24. https://doi.org/10.3390/pr12071341,
25. https://doi.org/10.1186/s12915-023-01684-1,
26. https://doi.org/10.1039/d3np00065f,
27. https://doi.org/10.1128/spectrum.05045-22,
28. https://doi.org/10.1186/s12934-025-02818-6,

BioReason-Pro RL Review: amyE (B. subtilis)

Source: amyE-deep-research-bioreason-rl.md

• Correctness: 5/5
• Completeness: 4/5

Functional Summary Review

The BioReason functional summary reads:

A secreted endo-acting starch hydrolase from Bacillus subtilis that initiates extracellular starch breakdown by binding insoluble polysaccharide granules and cleaving internal alpha-1,4 linkages to produce maltodextrins. Its catalytic core is stabilized by a C-terminal beta-sandwich and augmented by a distal immunoglobulin-like starch-binding appendage that concentrates substrate and enhances processivity. Operating outside the cell, it fuels nutrient acquisition by priming environmental starch for downstream catabolism and uptake.

This is an accurate and well-written summary. The description of AmyE as a secreted endo-acting starch hydrolase that cleaves internal alpha-1,4 linkages aligns with the curated annotation of alpha-amylase activity (GO:0004556). The mention of extracellular localization matches GO:0005576 (extracellular region). The description of the CBM26 starch-binding module and Ig-like fold is consistent with the curated polysaccharide binding annotation (GO:0030247).

The one notable omission is the calcium ion binding (GO:0005509) identified in the curated review as a core function -- AmyE binds two Ca2+ ions per subunit essential for structural stability, with binding sites characterized by X-ray crystallography. The BioReason summary does not mention calcium dependence, which is a functionally significant property. The curated review also provides more enzymatic detail (retaining double-displacement mechanism, specific catalytic residues Asp217/Glu249), though these are arguably beyond the scope of a functional summary.

Comparison with interpro2go:

The interpro2go annotations (GO_REF:0000002) for amyE include catalytic activity (GO:0003824), carbohydrate metabolic process (GO:0005975), and cation binding (GO:0043169). The curated review flags all three as too general and recommends more specific replacements. BioReason goes well beyond interpro2go by correctly identifying the specific alpha-amylase activity, starch catabolic process, and extracellular localization. BioReason does not recapitulate the interpro2go error of overly general terms. However, BioReason shares interpro2go's gap of missing calcium ion binding, though interpro2go at least captures the general "cation binding" signal.

Notes on thinking trace

The thinking trace demonstrates systematic domain-by-domain reasoning from IPR signatures to function. The reasoning from GH13 catalytic core through the stabilizing beta-sandwich to the CBM26 starch-binding module is logically sound. The inference of extracellular localization from the absence of transmembrane motifs and the presence of a signal peptide region is appropriate.