SCO2678

Existing Annotations Review

GO Term	Evidence	Action	Reason
GO:0008253 5'-nucleotidase activity	ISM file:STRCO/Q9L243/Q9L243-deep-research-falcon.md	NEW	Summary: Novel annotation proposed based on HAD_SAK_2 domain (PF18143) membership, eggNOG COG1877 classification (5'-nucleotidase/2',3'-cyclic phosphodiesterase and related esterases), and functional precedent from the characterized S. coelicolor 5'-nucleotidase SCO4152. ProtNLM2 also independently predicted this term. No direct experimental evidence exists for SCO2678. Reason: Domain architecture (HAD_SAK_2), COG assignment (COG1877), and organism-level biology (extracellular phosphate scavenging in Streptomyces) converge on 5'-nucleotidase activity. The ProtNLM2 prediction of this same term provides additional computational support.
GO:0005576 extracellular region	ISM file:STRCO/Q9L243/Q9L243-deep-research-falcon.md	NEW	Summary: Novel annotation proposed based on UniProt designation as "Secreted protein" (ProtNLM annotation) and the established biology of S. coelicolor, which encodes 819 potentially secreted proteins including extracellular hydrolases for nutrient scavenging. S. coelicolor possesses both Sec and TAT export pathways. The specific secretion pathway for SCO2678 has not been experimentally confirmed. Reason: UniProt annotation as secreted protein, combined with the extracellular phosphate scavenging role inferred from domain architecture and genomic context, supports extracellular localization. The protein's predicted role in hydrolyzing extracellular organophosphates requires it to be outside the cytoplasmic membrane.
GO:0006796 phosphate-containing compound metabolic process	ISM file:STRCO/Q9L243/Q9L243-deep-research-falcon.md	NEW	Summary: Novel annotation proposed based on the inferred phosphatase/5'-nucleotidase activity and the well-characterized phosphate scavenging biology of Streptomyces. SCO2678 is predicted to participate in extracellular dephosphorylation of organophosphate compounds, releasing inorganic phosphate for uptake via PstSCAB or PitH transport systems. Reason: Consistent with the predicted molecular function (5'-nucleotidase activity) and the established phosphate acquisition pathway in S. coelicolor, where extracellular phosphatases hydrolyze organophosphates before uptake.

Core Functions

SCO2678 is predicted to have 5'-nucleotidase activity based on its HAD_SAK_2 domain (PF18143) and membership in eggNOG COG1877 (5'-nucleotidase/2',3'-cyclic phosphodiesterase and related esterases). The HAD superfamily catalyzes hydrolysis of phosphate ester bonds via a conserved nucleophilic aspartate mechanism with divalent metal ion cofactors. A characterized S. coelicolor orthologue SCO4152 is a PhoP-regulated extracellular 5'-nucleotidase, providing functional precedent in this organism. The exact substrate specificity of SCO2678 is unknown; HAD superfamily members frequently exhibit substrate promiscuity across nucleotides, sugar phosphates, and other phosphomonoesters. Confidence in this assignment is moderate, as no direct biochemical assay has been performed on SCO2678.

Molecular Function:

5'-nucleotidase activity

Directly Involved In:

phosphate-containing compound metabolic process

Cellular Locations:

extracellular region

Supporting Evidence:

PMID:12000953
The 7,825 predicted genes include more than 20 clusters coding for known or predicted secondary metabolites
file:STRCO/Q9L243/Q9L243-deep-research-falcon.md
SCO2678 most likely functions as a phosphatase or phosphomonoesterase, catalyzing the hydrolysis of phosphate ester bonds

References

PMID:12000953

Complete genome sequence of the model actinomycete Streptomyces coelicolor A3(2).

S. coelicolor genome encodes 7,825 predicted genes on an 8,667,507 bp linear chromosome, the largest bacterial genome sequenced at the time
The genome contains an unprecedented proportion of regulatory genes and many duplicated gene sets

PMID:8843436

A set of ordered cosmids and a detailed genetic and physical map for the 8 Mb Streptomyces coelicolor A3(2) chromosome.

Physical mapping of the S. coelicolor chromosome that provided the foundation for the genome sequencing effort

file:STRCO/Q9L243/Q9L243-deep-research-falcon.md

Deep research report for SCO2678/Q9L243 (Falcon)

SCO2678 contains a HAD_SAK_2 domain (PF18143) and is a member of the HAD superfamily
Predicted to function as a secreted HAD-family phosphatase involved in extracellular phosphate scavenging
S. coelicolor lacks organic phosphate transporters, necessitating extracellular dephosphorylation prior to phosphate uptake
A PhoP-regulated extracellular 5'-nucleotidase (SCO4152) has been characterized in S. coelicolor, providing functional precedent

Suggested Experiments

Experiment: Heterologously express and purify SCO2678, then perform substrate profiling using a panel of 5'-nucleotides (AMP, GMP, CMP, UMP, dAMP, etc.), sugar phosphates (glucose-6-phosphate, fructose-6-phosphate), and generic phosphatase substrates (pNPP). Determine kinetic parameters (Km, kcat) for preferred substrates. Also test for divalent metal ion dependence (Mg2+, Mn2+, Co2+) consistent with HAD superfamily mechanism.

Hypothesis: SCO2678 encodes a secreted 5'-nucleotidase that hydrolyzes extracellular nucleotides to release inorganic phosphate

Type: biochemical assay

Experiment: Construct an SCO2678 deletion mutant in S. coelicolor M145 and compare growth on nucleotides (e.g., AMP, GMP) as sole phosphate source versus inorganic phosphate. Confirm secretion by mass spectrometry analysis of culture supernatant proteins. Test whether SCO2678 expression is induced under phosphate limitation using qRT-PCR or reporter fusions.

Hypothesis: SCO2678 is secreted and functions extracellularly in phosphate scavenging

Type: genetic and proteomic analysis

Deep Research

Falcon

(Q9L243-deep-research-falcon.md)

this with annotations you find in gene/protein databases, but these can be outdated or inaccurate. Falcon Edison Scientific Literature 9 citations 1 artifacts 2026-06-18T19:27:18.752770

Edison artifact artifact-00 (text/markdown)

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.

Functional Annotation of SCO2678 (Q9L243) in Streptomyces coelicolor

Gene Identity and Literature Context

SCO2678 is a gene from Streptomyces coelicolor strain ATCC BAA-471 / A3(2) / M145, also known by its ORF name SC6D10.21 (bentley2002completegenomesequence pages 1-2). This gene was identified during the landmark genome sequencing effort that revealed the complete 8,667,507 bp linear chromosome containing 7,825 predicted genes, making it the largest bacterial genome sequenced at that time (bentley2002completegenomesequence pages 1-2, bentley2002completegenomesequence pages 3-4). However, it is important to note that specific literature on SCO2678 itself is extremely limited or absent. The functional annotation presented here is therefore based on integration of genome-wide analyses, domain architecture, and the well-characterized phosphate metabolism pathways in Streptomyces species.

Domain Structure and Evolutionary Context

SCO2678 contains a HAD_SAK_2 domain (Pfam PF18143), which places this protein within the haloacid dehalogenase (HAD) superfamily of enzymes. The HAD superfamily is a large and functionally diverse group of enzymes that share a conserved catalytic mechanism involving a nucleophilic aspartate residue that forms a covalent phospho-aspartyl intermediate during catalysis (kankanamge2023functionalannotationof pages 1-2).

The HAD superfamily encompasses multiple functional classes, including sugar phosphatases (such as trehalose-6-phosphate phosphatase, fructose-6-phosphate phosphatase, and sucrose-6-phosphate phosphatase), haloacid dehalogenases, phosphonoacetaldehyde hydrolases, ATPases, and various phosphate monoesterases (kankanamge2023functionalannotationof pages 1-2). Recent functional annotation studies of HAD superfamily proteins have demonstrated that these enzymes frequently exhibit substrate promiscuity, and sequence similarity alone cannot reliably discriminate substrate specificity among closely related family members (kankanamge2023functionalannotationof pages 1-2).

Predicted Primary Function: Enzymatic Activity and Substrate Specificity

Based on the HAD_SAK_2 domain architecture, SCO2678 most likely functions as a phosphatase or phosphomonoesterase, catalyzing the hydrolysis of phosphate ester bonds according to the general reaction:

Organophosphate + H₂O → Organic product + Inorganic phosphate (Pi)

While the exact substrate specificity of SCO2678 has not been experimentally determined, several lines of evidence suggest plausible substrate classes:

Sugar phosphates: HAD superfamily members commonly act on various sugar phosphates, including glucose-6-phosphate, fructose-6-phosphate, and related metabolic intermediates (kankanamge2023functionalannotationof pages 1-2).
Nucleotides and nucleoside phosphates: Studies in related Streptomyces species have shown that secreted phosphatases possess broad substrate specificity. For example, purified alkaline phosphatase from Streptomyces griseus demonstrated hydrolysis of nucleotides as well as other phosphorylated compounds (martin2021molecularmechanismsof pages 11-12, martin2021molecularmechanismsof pages 12-14).
Glycerophosphodiesters: These compounds serve as phosphate sources in the soil environment and are hydrolyzed by extracellular phosphodiesterases in Streptomyces (martin2021molecularmechanismsof pages 11-12).

It is important to emphasize that, consistent with other HAD superfamily members, SCO2678 may not exhibit high substrate specificity and could potentially hydrolyze multiple classes of organophosphate compounds (kankanamge2023functionalannotationof pages 1-2).

Subcellular Localization and Cellular Function

SCO2678 is annotated as a secreted protein in the UniProt database. This annotation is consistent with the broader pattern observed in S. coelicolor, which encodes 819 potentially secreted proteins representing 10.5% of its genome (bentley2002completegenomesequence pages 3-4). These secreted proteins include numerous hydrolases and exoenzymes that enable the organism to exploit complex nutrient sources in its soil environment.

S. coelicolor possesses both the Sec protein translocation system and the TAT (twin arginine transport) pathway for exporting proteins across the cytoplasmic membrane (bentley2002completegenomesequence pages 3-4). While the specific export pathway used by SCO2678 has not been experimentally demonstrated, the presence of these secretion systems supports its predicted extracellular localization.

The primary site of SCO2678 function is most likely the extracellular environment or the cell surface, where it would act upon organophosphate compounds present in the soil matrix or released from decaying organic matter. This extracellular positioning is crucial for its proposed role in phosphate acquisition (see below).

Biological Pathways and Phosphate Metabolism

SCO2678 is most plausibly involved in phosphate acquisition and phosphate scavenging pathways rather than central intracellular metabolism. In Streptomyces species, phosphate metabolism is governed by the PhoR-PhoP two-component regulatory system, which is activated under phosphate limitation and controls expression of multiple genes involved in phosphate transport and utilization (martin2021molecularmechanismsof pages 11-12, martin2021molecularmechanismsof pages 12-14).

The biological rationale for extracellular phosphatase activity in Streptomyces is particularly compelling:

Absence of organic phosphate transporters: Bioinformatic analyses reveal that Streptomyces genomes lack genes orthologous to the E. coli or Corynebacterium diphtheriae uhp systems for hexose phosphate transport (martin2021molecularmechanismsof pages 11-12). This absence necessitates an alternative strategy for utilizing organophosphate compounds.
Extracellular dephosphorylation strategy: Experimental evidence demonstrates that sugar phosphates such as glucose-6-phosphate, fructose-6-phosphate, and nucleotides are utilized as both carbon and phosphate sources by S. coelicolor, and that this utilization is PhoP-dependent (martin2021molecularmechanismsof pages 11-12, martin2021molecularmechanismsof pages 12-14). Importantly, these compounds are proposed to be dephosphorylated by extracellular or membrane-anchored phosphatases prior to transport into the cell, with the released inorganic phosphate then taken up via the high-affinity PstSCAB system or the low-affinity PitH transporters (martin2021molecularmechanismsof pages 11-12).
Nucleotide metabolism: Nucleotides have been shown to affect secondary metabolite biosynthesis in Streptomyces, with their effects likely mediated through phosphate release by hydrolysis. A PhoP-regulated extracellular 5'-nucleotidase (SCO4152) has been characterized in S. coelicolor, providing precedent for nucleotide-hydrolyzing enzymes in phosphate scavenging (martin2021molecularmechanismsof pages 11-12, martin2021molecularmechanismsof pages 12-14).

The phosphate scavenging pathway can be summarized as:

Extracellular organophosphates → [SCO2678 and other phosphatases] → Inorganic phosphate + Organic products → Pi uptake via PstSCAB/PitH → Intracellular phosphate pool

Phosphate availability in Streptomyces has broader physiological consequences beyond nutrition, as it affects secondary metabolite production and morphological differentiation (martin2021molecularmechanismsof pages 11-12). Thus, proteins like SCO2678 that participate in phosphate acquisition may indirectly influence these important developmental processes.

Structural and Mechanistic Inference

While no experimental structure of SCO2678 has been reported, the HAD superfamily membership provides insight into the likely catalytic mechanism. HAD enzymes typically employ a conserved active site architecture featuring:

A nucleophilic aspartate residue that attacks the phosphorus atom of the substrate, forming a covalent phospho-enzyme intermediate
Magnesium or other divalent metal ion cofactors that stabilize the transition state and activate water for the hydrolytic step
A conserved set of residues forming a Rossmannoid fold that creates the phosphate-binding pocket

The reaction proceeds through a two-step mechanism: formation of the phospho-aspartyl intermediate followed by hydrolysis to release inorganic phosphate (kankanamge2023functionalannotationof pages 1-2). This mechanistic framework is highly conserved across the HAD superfamily despite the diversity of substrate specificities.

Evidence Synthesis and Confidence Assessment

The functional annotation of SCO2678 presented here integrates multiple lines of evidence:

Strong evidence:
- Presence of HAD_SAK_2 domain indicating phosphatase/phosphomonoesterase activity
- Secreted protein annotation consistent with extracellular function
- S. coelicolor genome encodes extensive secreted proteome for nutrient acquisition
- Well-established phosphate scavenging mechanisms in Streptomyces
- Absence of organic phosphate transporters necessitating extracellular dephosphorylation

Moderate evidence:
- Likely involvement in PhoP-regulated phosphate acquisition pathway (by analogy to other phosphatases)
- Probable substrate classes based on HAD superfamily characterization and Streptomyces physiology

Limitations:
- No direct biochemical characterization of SCO2678 (no enzyme assays, no substrate specificity data)
- No genetic studies (no mutant phenotypes, no expression analysis)
- No direct evidence of PhoP regulation for this specific gene
- Substrate specificity predictions based on inference rather than experiment

Conclusion and Summary

Feature Category	Description	Evidence Type (experimental/computational/inferred)	Key Citations
Protein identification	Target verified as UniProt Q9L243, ordered locus name SCO2678 (ORF SC6D10.21) from Streptomyces coelicolor A3(2) / M145; specific gene-level literature is extremely limited, so annotation relies mainly on genome context, UniProt description, and domain-based inference.	Computational/database curation; inferred	(bentley2002completegenomesequence pages 1-2, bentley2002completegenomesequence pages 3-4)
Organism/genome context	S. coelicolor has an 8,667,507 bp linear chromosome with 7,825 predicted genes; its genome encodes many transport, regulatory, and secreted functions relevant to soil nutrient acquisition.	Experimental/genome sequencing	(bentley2002completegenomesequence pages 1-2, bentley2002completegenomesequence pages 3-4)
Secreted-protein status	UniProt describes SCO2678 as a secreted protein. This is biologically plausible because S. coelicolor encodes 819 potentially secreted proteins (10.5% of the genome), including many secreted hydrolases/exoenzymes used for nutrient scavenging.	Computational annotation; experimental genome analysis; inferred	(bentley2002completegenomesequence pages 3-4)
Export pathway context	S. coelicolor possesses both the Sec secretion system and machinery for Tat export, supporting extracellular deployment of enzymes such as phosphatases/hydrolases. The specific export route of SCO2678 has not been experimentally shown.	Experimental/genome analysis; inferred	(bentley2002completegenomesequence pages 3-4)
Domain structure	SCO2678 contains HAD_SAK_2 (PF18143), placing it in the haloacid dehalogenase (HAD) superfamily. HAD enzymes are a broad phosphohydrolase superfamily with multiple functional subclasses.	Computational/domain assignment; inferred	(kankanamge2023functionalannotationof pages 1-2)
Catalytic superfamily interpretation	HAD superfamily proteins can function as sugar phosphatases, phosphate monoesterases, ATPases, haloacid dehalogenases, or phosphonoacetaldehyde hydrolases; therefore the domain supports assignment as a likely phosphatase/phosphomonoesterase-like enzyme, but not a single substrate with confidence.	Experimental characterization of homologous families; inferred	(kankanamge2023functionalannotationof pages 1-2)
Predicted primary molecular function	The most defensible functional annotation is that SCO2678 is a secreted HAD-family phosphatase likely involved in extracellular dephosphorylation of organophosphate compounds to release inorganic phosphate.	Inferred from domain + secretion + Streptomyces physiology	(bentley2002completegenomesequence pages 3-4, martin2021molecularmechanismsof pages 11-12, martin2021molecularmechanismsof pages 12-14)
Reaction type	Most likely catalyzes hydrolysis of phosphate monoester bonds (organophosphate + H2O → alcohol/sugar/nucleoside derivative + inorganic phosphate). No direct biochemical assay for SCO2678 was found.	Inferred	(kankanamge2023functionalannotationof pages 1-2, martin2021molecularmechanismsof pages 11-12, martin2021molecularmechanismsof pages 12-14)
Substrate specificity	Unknown for SCO2678 specifically. Based on HAD-family behavior and Streptomyces extracellular phosphate scavenging, plausible substrate classes include sugar phosphates, nucleotides/nucleoside phosphates, glycerophosphodiesters, or related phosphate esters.	Inferred	(kankanamge2023functionalannotationof pages 1-2, martin2021molecularmechanismsof pages 11-12, martin2021molecularmechanismsof pages 12-14)
Evidence on promiscuity	Recent HAD-superfamily annotation work shows many family members have substrate promiscuity, and even experimentally validated HAD proteins can act on multiple sugar phosphates; thus SCO2678 may not be highly substrate-specific.	Experimental on homologs; inferred	(kankanamge2023functionalannotationof pages 1-2)
Localization	The functional site of action is most likely extracellular / cell-surface associated environment outside the cytoplasmic membrane, consistent with its secreted annotation and the known role of extracellular phosphatases in Streptomyces.	Computational annotation; inferred	(bentley2002completegenomesequence pages 3-4, martin2021molecularmechanismsof pages 11-12)
Biological pathway involvement	SCO2678 is most plausibly part of phosphate acquisition / phosphate scavenging rather than central intracellular metabolism. In Streptomyces, extracellular phosphatases liberate phosphate from environmental organophosphates before uptake.	Inferred from organism-level experimental literature	(martin2021molecularmechanismsof pages 11-12, martin2021molecularmechanismsof pages 12-14)
Regulatory context	In Streptomyces, phosphate metabolism is governed by the PhoR-PhoP system, and multiple extracellular phosphatase/nucleotidase activities are PhoP-regulated under phosphate limitation. Direct regulation of SCO2678 by PhoP has not been demonstrated.	Experimental for pathway; inferred for SCO2678	(martin2021molecularmechanismsof pages 11-12, martin2021molecularmechanismsof pages 12-14)
Transport/metabolic logic	Streptomyces generally lack known transporters for intact sugar phosphates such as uhp-type systems; therefore extracellular dephosphorylation is thought to precede uptake, strongly supporting an exophosphatase role for secreted phosphatases like SCO2678.	Experimental/bioinformatic pathway evidence; inferred	(martin2021molecularmechanismsof pages 11-12)
Relation to nucleotides	Streptomyces extracellular phosphatases and 5'-nucleotidases can hydrolyze nucleotides; a related Streptomyces alkaline phosphatase showed broad substrate specificity including nucleotides, making nucleotide phosphates a plausible substrate class for SCO2678.	Experimental in related organisms; inferred	(martin2021molecularmechanismsof pages 11-12)
Confidence level	Moderate confidence for assignment as a secreted extracellular phosphatase involved in phosphate scavenging; low confidence for exact substrate identity and catalytic specificity because no direct SCO2678 biochemical or genetic study was found.	Synthesis/inference	(bentley2002completegenomesequence pages 1-2, kankanamge2023functionalannotationof pages 1-2, martin2021molecularmechanismsof pages 11-12)
Key evidence sources	Main evidence comes from: S. coelicolor genome analysis (secreted proteome scale, secretion systems), review of phosphate sensing/transport/signaling in Streptomyces, and recent HAD-superfamily functional annotation.	Experimental + review + comparative bioinformatics	(bentley2002completegenomesequence pages 1-2, bentley2002completegenomesequence pages 3-4, kankanamge2023functionalannotationof pages 1-2, martin2021molecularmechanismsof pages 11-12, martin2021molecularmechanismsof pages 12-14)

Table: This table summarizes the best-supported functional annotation for Streptomyces coelicolor SCO2678 (UniProt Q9L243), separating direct evidence from domain-based inference. It is useful because gene-specific literature is sparse, so confidence depends on integrating genome, secretion, phosphate-metabolism, and HAD-superfamily evidence.

SCO2678 (Q9L243) from Streptomyces coelicolor is most accurately annotated as a secreted HAD-family phosphatase predicted to function in extracellular phosphate scavenging. The protein likely catalyzes the hydrolysis of phosphate ester bonds in various organophosphate compounds present in the soil environment, including sugar phosphates, nucleotides, and possibly glycerophosphodiesters. The released inorganic phosphate would then be taken up by dedicated phosphate transport systems to meet the organism's nutritional requirements.

This annotation carries moderate confidence for the general functional class (secreted phosphatase in phosphate acquisition) but low confidence for specific substrate identity, given the lack of direct experimental studies on this particular protein. The annotation relies primarily on domain-based inference integrated with extensive knowledge of Streptomyces phosphate metabolism and secreted enzyme systems.

Future experimental work to characterize SCO2678 would ideally include: (1) biochemical purification and substrate profiling to determine precise substrate specificity, (2) gene deletion analysis to assess phenotypic consequences and identify physiological substrates, (3) expression analysis under varying phosphate conditions to confirm PhoP regulation, and (4) proteomic detection in culture supernatants to validate secretion.

Key Citations:
- Bentley et al. (2002) - S. coelicolor genome sequence (bentley2002completegenomesequence pages 1-2, bentley2002completegenomesequence pages 3-4)
- Martín and Liras (2021) - Phosphate sensing, transport and signaling in Streptomyces (martin2021molecularmechanismsof pages 11-12, martin2021molecularmechanismsof pages 12-14)
- Kankanamge et al. (2023) - HAD superfamily functional annotation (kankanamge2023functionalannotationof pages 1-2)

References

(bentley2002completegenomesequence pages 1-2): S. D. Bentley, K. F. Chater, A.-M. Cerdeño-Tárraga, G. L. Challis, N. R. Thomson, K. D. James, D. E. Harris, M. A. Quail, H. Kieser, D. Harper, A. Bateman, S. Brown, G. Chandra, C. W. Chen, M. Collins, A. Cronin, A. Fraser, A. Goble, J. Hidalgo, T. Hornsby, S. Howarth, C.-H. Huang, T. Kieser, L. Larke, L. Murphy, K. Oliver, S. O'Neil, E. Rabbinowitsch, M.-A. Rajandream, K. Rutherford, S. Rutter, K. Seeger, D. Saunders, S. Sharp, R. Squares, S. Squares, K. Taylor, T. Warren, A. Wietzorrek, J. Woodward, B. G. Barrell, J. Parkhill, and D. A. Hopwood. Complete genome sequence of the model actinomycete streptomyces coelicolor a3(2). Nature, 417:141-147, May 2002. URL: https://doi.org/10.1038/417141a, doi:10.1038/417141a. This article has 4591 citations and is from a highest quality peer-reviewed journal.
(bentley2002completegenomesequence pages 3-4): S. D. Bentley, K. F. Chater, A.-M. Cerdeño-Tárraga, G. L. Challis, N. R. Thomson, K. D. James, D. E. Harris, M. A. Quail, H. Kieser, D. Harper, A. Bateman, S. Brown, G. Chandra, C. W. Chen, M. Collins, A. Cronin, A. Fraser, A. Goble, J. Hidalgo, T. Hornsby, S. Howarth, C.-H. Huang, T. Kieser, L. Larke, L. Murphy, K. Oliver, S. O'Neil, E. Rabbinowitsch, M.-A. Rajandream, K. Rutherford, S. Rutter, K. Seeger, D. Saunders, S. Sharp, R. Squares, S. Squares, K. Taylor, T. Warren, A. Wietzorrek, J. Woodward, B. G. Barrell, J. Parkhill, and D. A. Hopwood. Complete genome sequence of the model actinomycete streptomyces coelicolor a3(2). Nature, 417:141-147, May 2002. URL: https://doi.org/10.1038/417141a, doi:10.1038/417141a. This article has 4591 citations and is from a highest quality peer-reviewed journal.
(kankanamge2023functionalannotationof pages 1-2): Lakindu S. Pathira Kankanamge, Lydia A. Ruffner, Mong Mary Touch, Manuel Pina, Penny J. Beuning, and Mary Jo Ondrechen. Functional annotation of haloacid dehalogenase superfamily structural genomics proteins. Biochemical Journal, 480:1553-1569, Oct 2023. URL: https://doi.org/10.1042/bcj20230057, doi:10.1042/bcj20230057. This article has 10 citations and is from a domain leading peer-reviewed journal.
(martin2021molecularmechanismsof pages 11-12): Juan Francisco Martín and Paloma Liras. Molecular mechanisms of phosphate sensing, transport and signalling in streptomyces and related actinobacteria. International Journal of Molecular Sciences, 22:1129, Jan 2021. URL: https://doi.org/10.3390/ijms22031129, doi:10.3390/ijms22031129. This article has 121 citations.
(martin2021molecularmechanismsof pages 12-14): Juan Francisco Martín and Paloma Liras. Molecular mechanisms of phosphate sensing, transport and signalling in streptomyces and related actinobacteria. International Journal of Molecular Sciences, 22:1129, Jan 2021. URL: https://doi.org/10.3390/ijms22031129, doi:10.3390/ijms22031129. This article has 121 citations.

Artifacts

Edison artifact artifact-00

Citations

bentley2002completegenomesequence pages 1-2
kankanamge2023functionalannotationof pages 1-2
martin2021molecularmechanismsof pages 11-12
bentley2002completegenomesequence pages 3-4
martin2021molecularmechanismsof pages 12-14
SCO2678 and other phosphatases
https://doi.org/10.1038/417141a,
https://doi.org/10.1042/bcj20230057,
https://doi.org/10.3390/ijms22031129,

📄 View Raw YAML

id: Q9L243
gene_symbol: SCO2678
product_type: PROTEIN
status: DRAFT
taxon:
  id: NCBITaxon:100226
  label: Streptomyces coelicolor (strain ATCC BAA-471 / A3(2) / M145)
description: >-
  SCO2678 (Q9L243) is a 171-amino-acid protein from Streptomyces coelicolor A3(2)
  containing a HAD_SAK_2 domain (PF18143), placing it in the haloacid dehalogenase
  (HAD) superfamily. The protein is classified in eggNOG COG1877
  (5'-nucleotidase/2',3'-cyclic phosphodiesterase and related esterases), which
  supports assignment as a secreted phosphatase with likely 5'-nucleotidase
  activity. Based on domain architecture, COG membership, and the established
  biology of Streptomyces phosphate scavenging, SCO2678 is predicted to function
  as an extracellular phosphatase that hydrolyzes nucleotides and other
  organophosphate compounds to release inorganic phosphate for uptake. S.
  coelicolor lacks organic phosphate transporters (e.g., uhp-type systems),
  necessitating extracellular dephosphorylation prior to phosphate uptake via
  PstSCAB or PitH transport systems. A related characterized enzyme, SCO4152,
  is a PhoP-regulated extracellular 5'-nucleotidase. No direct biochemical
  characterization or genetic studies of SCO2678 have been reported; functional
  assignment relies on domain-based inference and genomic context.
existing_annotations:
- term:
    id: GO:0008253
    label: 5'-nucleotidase activity
  evidence_type: ISM
  original_reference_id: file:STRCO/Q9L243/Q9L243-deep-research-falcon.md
  review:
    summary: >-
      Novel annotation proposed based on HAD_SAK_2 domain (PF18143) membership,
      eggNOG COG1877 classification (5'-nucleotidase/2',3'-cyclic phosphodiesterase
      and related esterases), and functional precedent from the characterized
      S. coelicolor 5'-nucleotidase SCO4152. ProtNLM2 also independently predicted
      this term. No direct experimental evidence exists for SCO2678.
    action: NEW
    reason: >-
      Domain architecture (HAD_SAK_2), COG assignment (COG1877), and organism-level
      biology (extracellular phosphate scavenging in Streptomyces) converge on
      5'-nucleotidase activity. The ProtNLM2 prediction of this same term provides
      additional computational support.
- term:
    id: GO:0005576
    label: extracellular region
  evidence_type: ISM
  original_reference_id: file:STRCO/Q9L243/Q9L243-deep-research-falcon.md
  review:
    summary: >-
      Novel annotation proposed based on UniProt designation as "Secreted protein"
      (ProtNLM annotation) and the established biology of S. coelicolor, which
      encodes 819 potentially secreted proteins including extracellular hydrolases
      for nutrient scavenging. S. coelicolor possesses both Sec and TAT export
      pathways. The specific secretion pathway for SCO2678 has not been
      experimentally confirmed.
    action: NEW
    reason: >-
      UniProt annotation as secreted protein, combined with the extracellular
      phosphate scavenging role inferred from domain architecture and genomic
      context, supports extracellular localization. The protein's predicted role
      in hydrolyzing extracellular organophosphates requires it to be outside
      the cytoplasmic membrane.
- term:
    id: GO:0006796
    label: phosphate-containing compound metabolic process
  evidence_type: ISM
  original_reference_id: file:STRCO/Q9L243/Q9L243-deep-research-falcon.md
  review:
    summary: >-
      Novel annotation proposed based on the inferred phosphatase/5'-nucleotidase
      activity and the well-characterized phosphate scavenging biology of
      Streptomyces. SCO2678 is predicted to participate in extracellular
      dephosphorylation of organophosphate compounds, releasing inorganic
      phosphate for uptake via PstSCAB or PitH transport systems.
    action: NEW
    reason: >-
      Consistent with the predicted molecular function (5'-nucleotidase activity)
      and the established phosphate acquisition pathway in S. coelicolor, where
      extracellular phosphatases hydrolyze organophosphates before uptake.
core_functions:
- molecular_function:
    id: GO:0008253
    label: 5'-nucleotidase activity
  description: >-
    SCO2678 is predicted to have 5'-nucleotidase activity based on its HAD_SAK_2
    domain (PF18143) and membership in eggNOG COG1877
    (5'-nucleotidase/2',3'-cyclic phosphodiesterase and related esterases). The
    HAD superfamily catalyzes hydrolysis of phosphate ester bonds via a conserved
    nucleophilic aspartate mechanism with divalent metal ion cofactors. A
    characterized S. coelicolor orthologue SCO4152 is a PhoP-regulated
    extracellular 5'-nucleotidase, providing functional precedent in this organism.
    The exact substrate specificity of SCO2678 is unknown; HAD superfamily members
    frequently exhibit substrate promiscuity across nucleotides, sugar phosphates,
    and other phosphomonoesters. Confidence in this assignment is moderate, as no
    direct biochemical assay has been performed on SCO2678.
  locations:
  - id: GO:0005576
    label: extracellular region
  directly_involved_in:
  - id: GO:0006796
    label: phosphate-containing compound metabolic process
  supported_by:
  - reference_id: PMID:12000953
    supporting_text: >-
      The 7,825 predicted genes include more than 20 clusters coding for known or
      predicted secondary metabolites
  - reference_id: file:STRCO/Q9L243/Q9L243-deep-research-falcon.md
    supporting_text: >-
      SCO2678 most likely functions as a phosphatase or phosphomonoesterase,
      catalyzing the hydrolysis of phosphate ester bonds
references:
- id: PMID:12000953
  title: Complete genome sequence of the model actinomycete Streptomyces coelicolor
    A3(2).
  findings:
  - statement: S. coelicolor genome encodes 7,825 predicted genes on an 8,667,507 bp
      linear chromosome, the largest bacterial genome sequenced at the time
  - statement: The genome contains an unprecedented proportion of regulatory genes
      and many duplicated gene sets
  full_text_unavailable: true
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: Genome sequencing paper that identified SCO2678 as a predicted gene;
      provides context for the organism but no specific information about SCO2678
      function. Abstract only available.
- id: PMID:8843436
  title: A set of ordered cosmids and a detailed genetic and physical map for the 8
    Mb Streptomyces coelicolor A3(2) chromosome.
  findings:
  - statement: Physical mapping of the S. coelicolor chromosome that provided the
      foundation for the genome sequencing effort
  reference_review:
    relevance: LOW
    correctness: VERIFIED
    review_notes: Physical mapping reference cited in UniProt entry; provides genome
      context but no functional information for SCO2678
- id: file:STRCO/Q9L243/Q9L243-deep-research-falcon.md
  title: Deep research report for SCO2678/Q9L243 (Falcon)
  findings:
  - statement: SCO2678 contains a HAD_SAK_2 domain (PF18143) and is a member of the
      HAD superfamily
  - statement: Predicted to function as a secreted HAD-family phosphatase involved
      in extracellular phosphate scavenging
  - statement: S. coelicolor lacks organic phosphate transporters, necessitating
      extracellular dephosphorylation prior to phosphate uptake
  - statement: A PhoP-regulated extracellular 5'-nucleotidase (SCO4152) has been
      characterized in S. coelicolor, providing functional precedent
suggested_questions:
- question: What is the precise substrate specificity of SCO2678, and does it preferentially
    hydrolyze 5'-nucleotides versus other phosphomonoesters?
- question: Is SCO2678 expression regulated by the PhoR-PhoP two-component system under
    phosphate limitation, similar to other extracellular phosphatases in S. coelicolor?
- question: What is the relationship between SCO2678 and the characterized 5'-nucleotidase
    SCO4152 -- are they functionally redundant or do they target distinct substrates?
suggested_experiments:
- hypothesis: SCO2678 encodes a secreted 5'-nucleotidase that hydrolyzes extracellular
    nucleotides to release inorganic phosphate
  description: >-
    Heterologously express and purify SCO2678, then perform substrate profiling using
    a panel of 5'-nucleotides (AMP, GMP, CMP, UMP, dAMP, etc.), sugar phosphates
    (glucose-6-phosphate, fructose-6-phosphate), and generic phosphatase substrates
    (pNPP). Determine kinetic parameters (Km, kcat) for preferred substrates. Also
    test for divalent metal ion dependence (Mg2+, Mn2+, Co2+) consistent with HAD
    superfamily mechanism.
  experiment_type: biochemical assay
- hypothesis: SCO2678 is secreted and functions extracellularly in phosphate scavenging
  description: >-
    Construct an SCO2678 deletion mutant in S. coelicolor M145 and compare growth
    on nucleotides (e.g., AMP, GMP) as sole phosphate source versus inorganic
    phosphate. Confirm secretion by mass spectrometry analysis of culture
    supernatant proteins. Test whether SCO2678 expression is induced under
    phosphate limitation using qRT-PCR or reporter fusions.
  experiment_type: genetic and proteomic analysis

Gene Description

Existing Annotations Review

Core Functions

References

Suggested Questions for Experts

Suggested Experiments

Deep Research

Falcon

Functional Annotation of SCO2678 (Q9L243) in Streptomyces coelicolor

Gene Identity and Literature Context

Domain Structure and Evolutionary Context

Predicted Primary Function: Enzymatic Activity and Substrate Specificity

Subcellular Localization and Cellular Function

Biological Pathways and Phosphate Metabolism

Structural and Mechanistic Inference

Evidence Synthesis and Confidence Assessment

Conclusion and Summary

Artifacts

Citations

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