fas1 (SPAC926.09c) encodes the beta subunit of the fission yeast type I fatty acid synthase (FAS), the orthologue of S. cerevisiae FAS1 (48% identity). Six fas1 beta and six fas2 (lsd1) alpha subunits form a 2.1-2.4 MDa barrel-shaped alpha6beta6 complex containing about six FMN. The beta subunit carries the acetyltransferase that primes the acyl carrier protein with acetyl-CoA, the malonyl/palmitoyl transferase that loads malonyl units and transfers the finished acyl chain to CoA, the 3-hydroxyacyl-ACP dehydratase, and the FMN-dependent NADPH enoyl-ACP reductase; the alpha subunit supplies the acyl carrier, ketoacyl synthase, ketoacyl reductase and phosphopantetheinyl transferase. Together they convert acetyl-CoA, malonyl-CoA and NADPH into long-chain (C16/C18) acyl-CoA in the cytosol. The subunit composition matches the budding-yeast enzyme.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0004312 fatty acid synthase activity | IBA GO_REF:0000033 | MODIFY | Summary: IBA fatty acid synthase activity from PTN004213061, whose experimental donor is fas1 itself (its IDA). GO:0004312 (EC 2.3.1.85) is the animal-type FAS activity that releases free fatty acid via a thioesterase; the fungal alpha6beta6 FAS (EC 2.3.1.86) releases acyl-CoA through the malonyl/palmitoyl transferase of this beta subunit, so GO:0004321 is the correct overall activity (as in the S. cerevisiae FAS1/FAS2 reviews and the PomBase GO-CAM, which types the complex activity as GO:0004321). Reason: Fungal FAS forms acyl-CoA (EC 2.3.1.86), not free fatty acid. Proposed replacements: fatty-acyl-CoA synthase activity Supporting Evidence: file:SCHPO/fas1/fas1-uniprot.txt Reaction=acetyl-CoA + n malonyl-CoA + 2n NADPH + 4n H(+) = a long- PMID:9693066 The isolated FAS complex showed quite high specific activity, of more than 4000 mU/mg, suggesting complete purification |
| GO:0004312 fatty acid synthase activity | IDA PMID:9693066 Cloning of the fatty acid synthetase beta subunit from fissi... | MODIFY | Summary: IDA (Niwa et al. 1998): co-expressed and purified S. pombe Fas1/Fas2 complex has high FAS specific activity. The activity is real, but GO:0004312 (EC 2.3.1.85) is the animal-type FAS activity that releases free fatty acid via a thioesterase; the fungal alpha6beta6 FAS (EC 2.3.1.86) releases acyl-CoA through the malonyl/palmitoyl transferase of this beta subunit, so GO:0004321 is the correct overall activity (as in the S. cerevisiae FAS1/FAS2 reviews and the PomBase GO-CAM, which types the complex activity as GO:0004321). As a subunit, fas1 contributes to the complex activity. Reason: Use fatty-acyl-CoA synthase activity (contributes_to) for the fungal complex. Proposed replacements: fatty-acyl-CoA synthase activity Supporting Evidence: PMID:9693066 The isolated FAS complex showed quite high specific activity, of more than 4000 mU/mg, suggesting complete purification file:SCHPO/fas1/fas1-uniprot.txt Reaction=acetyl-CoA + n malonyl-CoA + 2n NADPH + 4n H(+) = a long- |
| GO:0004312 fatty acid synthase activity | IEA GO_REF:0000002 | MODIFY | Summary: InterPro IPR003965 (fungal FAS beta) mapping to fatty acid synthase activity. GO:0004312 (EC 2.3.1.85) is the animal-type FAS activity that releases free fatty acid via a thioesterase; the fungal alpha6beta6 FAS (EC 2.3.1.86) releases acyl-CoA through the malonyl/palmitoyl transferase of this beta subunit, so GO:0004321 is the correct overall activity (as in the S. cerevisiae FAS1/FAS2 reviews and the PomBase GO-CAM, which types the complex activity as GO:0004321). Reason: Fungal FAS forms acyl-CoA. Proposed replacements: fatty-acyl-CoA synthase activity Supporting Evidence: file:SCHPO/fas1/fas1-uniprot.txt Reaction=acetyl-CoA + n malonyl-CoA + 2n NADPH + 4n H(+) = a long- |
| GO:0004313 [acyl-carrier-protein] S-acetyltransferase activity | IEA GO_REF:0000120 | ACCEPT | Summary: IEA (InterPro IPR016452, RHEA:41788, EC 2.3.1.38) for the acetyltransferase (AT) domain of the beta subunit that primes the ACP with acetyl-CoA. Correct; core partial activity. Supporting Evidence: file:SCHPO/fas1/fas1-uniprot.txt Reaction=holo-[ACP] + acetyl-CoA = acetyl-[ACP] + CoA; file:SCHPO/fas1/fas1-uniprot.txt fatty acids from acetyl-CoA, malonyl-CoA and NADPH. The beta subunit |
| GO:0004313 [acyl-carrier-protein] S-acetyltransferase activity | ISO GO_REF:0000024 | ACCEPT | Summary: ISO from S. cerevisiae FAS1 (SGD:S000001665), whose isolated beta chain carries acetyltransferase activity. fas1 shares 48% identity and the same domain set. Correct. Supporting Evidence: file:SCHPO/fas1/fas1-uniprot.txt Reaction=holo-[ACP] + acetyl-CoA = acetyl-[ACP] + CoA; PMID:9693066 This subunit, with five different catalytic activities, bears four distinct domains |
| GO:0004314 [acyl-carrier-protein] S-malonyltransferase activity | IEA GO_REF:0000120 | ACCEPT | Summary: IEA (InterPro IPR016452, EC 2.3.1.39) for the malonyl/palmitoyl transferase (MPT) domain, which loads malonyl units and also transfers the finished acyl chain to CoA. Correct; core. Supporting Evidence: file:SCHPO/fas1/fas1-uniprot.txt Reaction=holo-[ACP] + malonyl-CoA = malonyl-[ACP] + CoA; file:SCHPO/fas1/fas1-uniprot.txt fatty acids from acetyl-CoA, malonyl-CoA and NADPH. The beta subunit |
| GO:0004314 [acyl-carrier-protein] S-malonyltransferase activity | ISO GO_REF:0000024 | ACCEPT | Summary: ISO from S. cerevisiae FAS1 (MPT activity shown on isolated beta subunit). Correct; PomBase GO-CAM uses this for fas1. Supporting Evidence: file:SCHPO/fas1/fas1-uniprot.txt Reaction=holo-[ACP] + malonyl-CoA = malonyl-[ACP] + CoA; PMID:9693066 This subunit, with five different catalytic activities, bears four distinct domains |
| GO:0004318 enoyl-[acyl-carrier-protein] reductase (NADH) activity | IEA GO_REF:0000120 | MODIFY | Summary: IEA (RHEA:10240 / EC 1.3.1.9, NADH-dependent enoyl-ACP reductase). The fungal FAS enoyl reductase is an FMN-dependent NADPH enzyme: the S. pombe complex contains ~six FMN and the overall reaction consumes NADPH. The activity (enoyl-ACP reduction by the ER domain) is right but the cofactor is wrong; replace with the NADPH-specific term used in the S. cerevisiae FAS1 review (which removed the NADH rows). Reason: NADPH-, not NADH-dependent enoyl-ACP reductase. Proposed replacements: enoyl-[acyl-carrier-protein] reductase (NADPH) activity Supporting Evidence: PMID:9693066 one molecule of the FAS complex was found to contain approximately six FMN molecules file:SCHPO/fas1/fas1-uniprot.txt Reaction=acetyl-CoA + n malonyl-CoA + 2n NADPH + 4n H(+) = a long- |
| GO:0004318 enoyl-[acyl-carrier-protein] reductase (NADH) activity | ISO GO_REF:0000024 | MODIFY | Summary: ISO from S. cerevisiae FAS1 for the NADH-dependent enoyl-ACP reductase. The ER domain is real (and used in the PomBase GO-CAM with this NADH term), but fungal FAS reduces with NADPH via FMN; the S. cerevisiae FAS1 review carries GO:0141148. Modify. Reason: Cofactor should be NADPH. Proposed replacements: enoyl-[acyl-carrier-protein] reductase (NADPH) activity Supporting Evidence: PMID:9693066 one molecule of the FAS complex was found to contain approximately six FMN molecules file:SCHPO/fas1/fas1-uniprot.txt Reaction=acetyl-CoA + n malonyl-CoA + 2n NADPH + 4n H(+) = a long- |
| GO:0004321 fatty-acyl-CoA synthase activity | IEA GO_REF:0000003 | ACCEPT | Summary: IEA from EC 2.3.1.86 (fatty-acyl-CoA synthase). Correct overall activity of the alpha6beta6 complex; fas1 contributes to it with fas2. Supporting Evidence: file:SCHPO/fas1/fas1-uniprot.txt Reaction=acetyl-CoA + n malonyl-CoA + 2n NADPH + 4n H(+) = a long- PMID:9693066 These results indicate that the FAS complex from S. pombe forms a heterododecameric alpha6beta6 structure |
| GO:0004321 fatty-acyl-CoA synthase activity | NAS GO_REF:0000051 | ACCEPT | Summary: PomBase NAS (GO_REF:0000051) fatty-acyl-CoA synthase activity. Correct and consistent with the purified complex activity and with the PomBase GO-CAM complex node; core (as contribution to the complex). Supporting Evidence: PMID:9693066 The isolated FAS complex showed quite high specific activity, of more than 4000 mU/mg, suggesting complete purification file:SCHPO/fas1/fas1-uniprot.txt Reaction=acetyl-CoA + n malonyl-CoA + 2n NADPH + 4n H(+) = a long- |
| GO:0005829 cytosol | HDA PMID:16823372 ORFeome cloning and global analysis of protein localization ... | ACCEPT | Summary: ORFeome screen, cytosol. The FAS barrel is a soluble cytosolic complex; matches the GO-CAM. Supporting Evidence: PMID:16823372 we determined the localization of 4,431 proteins, corresponding to approximately 90% of the fission yeast proteome |
| GO:0005835 fatty acid synthase complex | IBA GO_REF:0000033 | ACCEPT | Summary: IBA from fungal FAS node PTN000104897 (C. albicans, S. cerevisiae FAS1, S. pombe fas1 donors). Correct. Supporting Evidence: PMID:9693066 These results indicate that the FAS complex from S. pombe forms a heterododecameric alpha6beta6 structure |
| GO:0005835 fatty acid synthase complex | IDA PMID:9693066 Cloning of the fatty acid synthetase beta subunit from fissi... | ACCEPT | Summary: IDA (Niwa et al. 1998): co-purified alpha6beta6 complex of 2.1-2.4 MDa with barrel-shaped cage architecture. Core complex. Supporting Evidence: PMID:9693066 These results indicate that the FAS complex from S. pombe forms a heterododecameric alpha6beta6 structure |
| GO:0005835 fatty acid synthase complex | IEA GO_REF:0000120 | ACCEPT | Summary: IEA (ARBA00088603, InterPro IPR003965/IPR016452). Correct. Supporting Evidence: PMID:9693066 These results indicate that the FAS complex from S. pombe forms a heterododecameric alpha6beta6 structure |
| GO:0005835 fatty acid synthase complex | IPI PMID:9693066 Cloning of the fatty acid synthetase beta subunit from fissi... | ACCEPT | Summary: IPI from the same co-expression/co-purification of Fas1 with Fas2 (lsd1). Correct. Supporting Evidence: PMID:9693066 These results indicate that the FAS complex from S. pombe forms a heterododecameric alpha6beta6 structure |
| GO:0006633 fatty acid biosynthetic process | IDA PMID:9693066 Cloning of the fatty acid synthetase beta subunit from fissi... | TOO GENERAL | Summary: IDA fatty acid biosynthetic process from the active purified complex. Correct; GO:0042759 is the more specific process also annotated. Supporting Evidence: PMID:9693066 The isolated FAS complex showed quite high specific activity, of more than 4000 mU/mg, suggesting complete purification |
| GO:0006633 fatty acid biosynthetic process | IEA GO_REF:0000002 | TOO GENERAL | Summary: InterPro FAS beta-subunit mapping. Correct. Supporting Evidence: file:SCHPO/fas1/fas1-uniprot.txt fatty acids from acetyl-CoA, malonyl-CoA and NADPH. The beta subunit |
| GO:0016297 fatty acyl-[ACP] hydrolase activity | IEA GO_REF:0000120 | REMOVE | Summary: IEA via RHEA:15057 / EC 3.1.2.14 (acyl-ACP thioesterase releasing free fatty acid), driven by UniProt naming an 'S-acyl fatty acid synthase thioesterase' domain. Fungal FAS has no chain-releasing thioesterase: the acyl chain is transferred to CoA by the MPT domain and the product is acyl-CoA. Removed, as in the S. cerevisiae FAS1 review. Reason: Fungal FAS releases acyl-CoA via transferase, not free fatty acid via hydrolase. Supporting Evidence: file:SCHPO/fas1/fas1-uniprot.txt Reaction=acetyl-CoA + n malonyl-CoA + 2n NADPH + 4n H(+) = a long- |
| GO:0016740 transferase activity | IEA GO_REF:0000002 | TOO GENERAL | Summary: InterPro IPR001227 (acyl transferase domain) mapping to 'transferase activity'. True but uninformative parent of the AT/MPT activities; non-core. Supporting Evidence: file:SCHPO/fas1/fas1-uniprot.txt Reaction=holo-[ACP] + acetyl-CoA = acetyl-[ACP] + CoA; |
| GO:0016747 acyltransferase activity, transferring groups other than amino-acyl groups | IEA GO_REF:0000117 | TOO GENERAL | Summary: ARBA00027717 acyltransferase (non-aminoacyl) parent of the AT/MPT activities; uninformative, non-core (as in FAS1 review). Supporting Evidence: file:SCHPO/fas1/fas1-uniprot.txt Reaction=holo-[ACP] + malonyl-CoA = malonyl-[ACP] + CoA; |
| GO:0019171 (3R)-hydroxyacyl-[acyl-carrier-protein] dehydratase activity | IEA GO_REF:0000120 | ACCEPT | Summary: IEA (InterPro, RHEA:13097, EC 4.2.1.59) for the 3-hydroxyacyl-ACP dehydratase (DH) domain. Correct; core partial activity. Supporting Evidence: file:SCHPO/fas1/fas1-uniprot.txt Reaction=a (3R)-hydroxyacyl-[ACP] = a (2E)-enoyl-[ACP] + H2O; |
| GO:0019171 (3R)-hydroxyacyl-[acyl-carrier-protein] dehydratase activity | ISO GO_REF:0000024 | ACCEPT | Summary: ISO from S. cerevisiae FAS1 (dehydratase is a beta-chain activity). Correct. Supporting Evidence: file:SCHPO/fas1/fas1-uniprot.txt Reaction=a (3R)-hydroxyacyl-[ACP] = a (2E)-enoyl-[ACP] + H2O; PMID:9693066 This subunit, with five different catalytic activities, bears four distinct domains |
| GO:0042759 long-chain fatty acid biosynthetic process | IBA GO_REF:0000033 | ACCEPT | Summary: IBA long-chain fatty acid biosynthetic process (PTN004213061; fas1 and S. cerevisiae FAS1). Core BP. Supporting Evidence: file:SCHPO/fas1/fas1-uniprot.txt Reaction=acetyl-CoA + n malonyl-CoA + 2n NADPH + 4n H(+) = a long- PMID:9693066 The isolated FAS complex showed quite high specific activity, of more than 4000 mU/mg, suggesting complete purification |
| GO:0042759 long-chain fatty acid biosynthetic process | IDA PMID:9693066 Cloning of the fatty acid synthetase beta subunit from fissi... | ACCEPT | Summary: IDA from the purified active FAS complex, which makes C16/C18 acyl chains. Core BP. Supporting Evidence: PMID:9693066 The isolated FAS complex showed quite high specific activity, of more than 4000 mU/mg, suggesting complete purification |
| GO:0042759 long-chain fatty acid biosynthetic process | IEA GO_REF:0000117 | ACCEPT | Summary: ARBA00034980 prediction. Correct. Supporting Evidence: file:SCHPO/fas1/fas1-uniprot.txt Reaction=acetyl-CoA + n malonyl-CoA + 2n NADPH + 4n H(+) = a long- |
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Download this section (compressed HTML)Q: Does any fas1 protein act in mitochondria, as the PomBase fatty-acid GO-CAM implies by placing a fas1 acetyltransferase activity in the mitochondrion, or is that node meant for the mitochondrial FAS II pathway?
Experiment: Assay the individual partial activities (AT, MPT, DH, ER) of the purified S. pombe FAS and its fas1 point mutants, and determine the product chain-length distribution (C16 vs C18 acyl-CoA).
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