Isopenicillin-N N-acyltransferase (IAT) that catalyzes the final step in penicillin biosynthesis. The enzyme exchanges the Ξ±-aminoadipyl side chain of isopenicillin N for phenylacetic acid to produce penicillin G. Functions as a self-processing enzyme that is initially synthesized as a 40 kDa precursor and undergoes autocatalytic cleavage to form an active heterodimer containing 11 kDa and 29 kDa subunits. Located in the peroxisomal matrix where penicillin biosynthesis occurs.
The preferred accession for this review is P15802. These relationships are manually assessed.
REFERENCE PROTEOME EQUIVALENT Β· Reviewed 2026-10-19
Reference proteome: UP001220256
Retain P15802 as the primary Swiss-Prot accession. The 357-residue reference sequence differs at two residues with full ungapped coverage (99.44% identity). The other retrieved hit is distant and structurally dissimilar. This supports a qualified sequence-based counterpart; the source strain is AS-P-78 and no functional neutrality of the two substitutions is assumed.
MMseqs2 searched 12,232 sequences across UP001220256 at E <= 1e-5 and sensitivity 7.5, returning 2 hits. Every returned sequence was globally aligned using BLOSUM62 with gap-open -10 and extension -0.5. Scores and sequences for all 2 returned candidates are retained, with 2 detailed alignment files. The heuristic search does not establish genomic absence or unique locus identity.
file:PENCH/aatA/aatA-record-evidence.yaml
target_sequence_count: 12232
file:PENCH/aatA/aatA-record-evidence.yaml
candidate_count: 2
A0ABQ8WFJ5: 355 identities across 357 global-alignment columns (99.4398% identity including gaps), 2 substitutions and 0 gap columns. Query coverage is 100.0%; target coverage is 100.0%. Sequence similarity is interpreted in the manual rationale. Identity over paired residues is 99.4398% (355/357); gap columns are excluded from this denominator.
file:PENCH/aatA/aatA-record-evidence.yaml
query_length: 357 target_length: 357 alignment_columns: 357 identities: 355 mismatches: 2 gap_columns: 0 identity_percent: 99.4398 query_coverage_percent: 100.0 target_coverage_percent: 100.0
The primary accession is outside every searched exact-taxon reference proteome. Current UniProt records place A0ABQ8WFJ5 in UP001220256 and give it the same taxon as the primary.
file:PENCH/aatA/aatA-record-evidence.yaml
primary_in_any_reference_proteome: false
file:PENCH/aatA/aatA-record-evidence.yaml
alternative_in_reference_proteome: true
file:PENCH/aatA/aatA-record-evidence.yaml
same_taxon: true
Sampled UniSave observations: 11-NOV-2015, entry version 79.: no Proteomes cross-reference; 12-AUG-2020, entry version 87.: no Proteomes cross-reference; 27-NOV-2024, entry version 97.: no Proteomes cross-reference. These dated observations do not establish uninterrupted membership/absence, the exact change date, or UniProt's motivation.
file:PENCH/aatA/aatA-record-evidence.yaml
entry_date: 11-NOV-2015, entry version 79. proteomes: []
file:PENCH/aatA/aatA-record-evidence.yaml
entry_date: 12-AUG-2020, entry version 87. proteomes: []
file:PENCH/aatA/aatA-record-evidence.yaml
entry_date: 27-NOV-2024, entry version 97. proteomes: []
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0005777 peroxisome | IEA GO_REF:0000043 | ACCEPT | Summary: Correct subcellular location annotation. UniProt confirms peroxisomal localization with IDA evidence. Supporting Evidence: UniProt:P15802 SUBCELLULAR LOCATION: Peroxisome matrix file:PENCH/aatA/aatA-deep-research.md whose proper localization to microbodies is required for efficient antibiotic biosynthesis |
| GO:0005782 peroxisomal matrix | IEA GO_REF:0000044 | ACCEPT | Summary: Correct specific subcellular location annotation. UniProt confirms peroxisomal matrix localization with IDA evidence. Supporting Evidence: PMID:18439860 The unprocessed preprotein form IATC103S of the isopenicillin N acyltransferase is transported inside peroxisomes |
| GO:0016740 transferase activity | IEA GO_REF:0000043 | KEEP AS NON CORE | Summary: Too general but correct. The enzyme has specific acyltransferase activity. Supporting Evidence: UniProt:P15802 Isopenicillin-N N-acyltransferase; part of the gene cluster that mediates the biosynthesis of penicillin |
| GO:0016746 acyltransferase activity | IEA GO_REF:0000043 | MODIFY | Summary: Correct but not specific enough. The enzyme has specific isopenicillin-N N-acyltransferase activity. Proposed replacements: isopenicillin-N N-acyltransferase activity Supporting Evidence: PMID:2120195 removal of the L-alpha-aminoadipyl side chain from isopenicillin N (IPN) and exchange with a nonpolar side chain |
| GO:0017000 antibiotic biosynthetic process | IEA GO_REF:0000043 | MODIFY | Summary: Correct but not specific enough. The enzyme is involved in penicillin biosynthesis specifically. Proposed replacements: penicillin biosynthetic process Supporting Evidence: PMID:1368505 A cosmid clone containing the putative penicillin biosynthetic gene cluster from Penicillium chrysogenum |
| GO:0042318 penicillin biosynthetic process | IEA GO_REF:0000117 | ACCEPT | Summary: Correct annotation representing the core function of this enzyme. Supporting Evidence: PMID:2120195 The final step in the biosynthesis of beta-lactam antibiotics in Penicillium chrysogenum and Aspergillus nidulans involves removal of the L-alpha-aminoadipyl side chain from isopenicillin N |
| GO:0050640 isopenicillin-N N-acyltransferase activity | IEA GO_REF:0000120 | ACCEPT | Summary: Correct and specific molecular function annotation representing the core enzymatic activity. Supporting Evidence: UniProt:P15802 AatA catalyzes the exchange of the alpha-aminoadipyl side chain of isopenicillin N for phenylacetic acid to yield penicillin |
| GO:0042318 penicillin biosynthetic process | IDA PMID:2120195 Molecular characterization of the acyl-coenzyme A:isopenicil... | ACCEPT | Summary: Correct annotation with strong experimental evidence (IDA). Supporting Evidence: PMID:2120195 Acyltransferase activity from Escherichia coli producing the 40-kDa protein |
| GO:0005782 peroxisomal matrix | IDA PMID:18439860 The unprocessed preprotein form IATC103S of the isopenicilli... | ACCEPT | Summary: Correct subcellular location with strong experimental evidence (IDA). Supporting Evidence: PMID:18439860 Unprocessed preprotein form IATC103S of the isopenicillin N acyltransferase is transported inside peroxisomes |
| GO:0042318 penicillin biosynthetic process | IDA PMID:1368505 Cloning and heterologous expression of the penicillin biosyn... | ACCEPT | Summary: Correct annotation with strong experimental evidence showing functional penicillin biosynthesis. Supporting Evidence: PMID:1368505 Both of the transformed hosts contained intact P. chrysogenum DNA derived from the cosmid clone and produced authentic penicillin V |
| GO:0050640 isopenicillin-N N-acyltransferase activity | IDA PMID:2120195 Molecular characterization of the acyl-coenzyme A:isopenicil... | ACCEPT | Summary: Correct and specific molecular function with strong experimental evidence (IDA). Supporting Evidence: PMID:2120195 The enzyme catalyzing this reaction, acyl-coenzyme A:isopenicillin N acyltransferase (acyltransferase), was purified from P. chrysogenum |
| GO:0008234 cysteine-type peptidase activity | IEA | NEW | Summary: AatA functions as a self-processing enzyme that undergoes autocatalytic cleavage using Cys103 as the nucleophile to generate the active heterodimeric form. Reason: This molecular function term captures AatA's cysteine-dependent autoproteolytic activity that is essential for enzyme maturation and activation. Supporting Evidence: PMID:20223213 Structure of a Cys103Ala precursor mutant shows that maturation is autoproteolytic, initiated by Cys103 cleaving its preceding peptide bond PMID:2120195 The active form of the enzyme may result from processing of the 40-kDa monomeric precursor to a heterodimer containing subunits of 11 and 29 kDa file:PENCH/aatA/aatA-bioinformatics/RESULTS.md All structures show cleavage between Gly102 and Cys103, creating heterodimeric subunits |
| GO:0097264 self proteolysis | IEA | NEW | Summary: AatA undergoes autocatalytic cleavage to convert from an inactive 40 kDa precursor to an active heterodimeric enzyme with 11 kDa and 29 kDa subunits. Reason: This biological process term describes AatA's essential autoproteolytic maturation step that is required for enzymatic activity in penicillin biosynthesis. Supporting Evidence: PMID:18439860 IAT is post-translationally regulated by its preprotein, which interferes with the self-processing. PMID:20223213 The structure of a Cys103Ala precursor mutant shows that maturation is autoproteolytic, initiated by Cys103 cleaving its preceding peptide bond. PMID:2120195 The active form of the enzyme may result from processing of the 40-kDa monomeric precursor to a heterodimer containing subunits of 11 and 29 kDa. |
| GO:0005782 peroxisomal matrix | IEA GO_REF:0000120 | ACCEPT | Summary: Combined automated (ARBA + UniProt subcellular location) peroxisomal matrix annotation; current replacement of the retired GO_REF:0000044 row. Consistent with direct localization of IAT (including the unprocessed C103S proenzyme) inside peroxisomes. Reason: Matches the experimentally determined peroxisomal matrix localization (IDA, PMID:18439860), where the final step of penicillin biosynthesis occurs. Supporting Evidence: PMID:18439860 Expression of a mutant penDE(C103S) gene in P. chrysogenum gave rise to an unprocessed inactive variant of IAT (IAT(C103S)) located inside peroxisomes |
| GO:0050640 isopenicillin-N N-acyltransferase activity | EXP PMID:1368505 Cloning and heterologous expression of the penicillin biosyn... | ACCEPT | Summary: Heterologous expression of the P. chrysogenum penicillin cluster cosmid in N. crassa and A. niger conferred acyl-CoA:6-APA acyltransferase (ACT/IAT) activity together with penicillin V production. Experimental support for the core acyltransferase activity encoded by penDE/aatA. Reason: Curator EXP annotation consistent with the purified-enzyme and recombinant evidence (PMID:2120195, PMID:2110531); the cosmid-based assay is indirect for the individual gene but the activity is unambiguously that of aatA. Abstract-only cache; defer to curator. Supporting Evidence: PMID:1368505 Assays of penicillin biosynthetic enzyme activity additionally demonstrated that they possessed delta-(L-alpha-amino-adipyl)-L-cysteinyl-D-valine synthetase (ACVS), isopenicillin N synthetase (IPNS) and acyl coenzyme A:6-aminopenicillanic acid acyltransferase (ACT) activity |
| GO:0050640 isopenicillin-N N-acyltransferase activity | EXP PMID:2110531 Acyl coenzyme A: 6-aminopenicillanic acid acyltransferase fr... | ACCEPT | Summary: Purified P. chrysogenum/A. nidulans acyltransferase (40 kDa) transfers the phenylacetyl group from phenylacetyl-CoA to 6-APA and converts isopenicillin N to benzylpenicillin; direct enzymatic evidence for isopenicillin-N N-acyltransferase activity. Reason: Direct assay of purified enzyme demonstrating the core catalytic activity. Supporting Evidence: PMID:2110531 It also catalyses the conversion of isopenicillin N (IPN) to benzylpenicillin (Pen G) and hydrolyses IPN to 6-APA |
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Download this section (compressed HTML)Q: Does the unprocessed proIAT preprotein regulate self-processing of the wild-type enzyme in vivo under industrial production conditions, and does processing efficiency limit penicillin titers?
Q: Which hydrophobic acyl-CoA side-chain donors are preferred in vivo, and how does the flexible substrate pocket of the mature enzyme determine this?
Experiment: Kinetic comparison of the acyltransferase, IPN amidohydrolase and 6-APA acyltransferase partial reactions of mature IAT with a panel of acyl-CoA donors
Experiment: Time-resolved analysis of proIAT autoprocessing in peroxisomes using processing-deficient (C103S) and wild-type co-expression strains
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