POT1 (FOX3) encodes the peroxisomal 3-ketoacyl-CoA thiolase (acetyl-CoA C-acyltransferase, EC 2.3.1.16) of Saccharomyces cerevisiae, the enzyme of the final step of each peroxisomal fatty acid beta-oxidation cycle. It cleaves a 3-oxoacyl-CoA with free CoA to release acetyl-CoA and an acyl-CoA shortened by two carbons. In yeast, beta-oxidation is confined to peroxisomes, and POT1 is the main thiolase there. The enzyme is a soluble homodimer (45 kDa subunits) of the peroxisomal matrix. It is imported by the PTS2 pathway: its N-terminal 16 residues form a PTS2 that is recognised by the Pex7p receptor together with the Pex18p/Pex21p co-receptors. Expression is induced by oleate, and fox3 mutants are blocked at the thiolase step of fatty acid degradation. A minor pool has been reported in the mitochondrial intermembrane space, and high-throughput screens detected mRNA binding and in vitro antifungal activity, but none of these has a defined physiological role.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0003729 mRNA binding | IDA PMID:21124907 A screen for RNA-binding proteins in yeast indicates dual fu... | KEEP AS NON CORE | Summary: Tsvetanova et al. identified Pot1p in a proteome-wide screen for RNA-binding proteins and found that its associated mRNAs are enriched for translation-related messages. This is a real experimental observation, but no function for Pot1p mRNA binding has been shown, and many metabolic enzymes were recovered in the same screen. Kept as a non-core, possible moonlighting activity. Supporting Evidence: PMID:21124907 For instance, messages associated with Map1p, Pot1p, and Ymr1p are commonly related to translation. |
| GO:0003988 acetyl-CoA C-acyltransferase activity | IBA GO_REF:0000033 | ACCEPT | Summary: IBA from PTN001823071 (thiolase family). SGD:S000001422 (POT1) is one of the experimental descendants. Pot1p is a canonical peroxisomal 3-ketoacyl-CoA thiolase, so inheriting the activity is correct. Supporting Evidence: file:yeast/POT1/POT1-uniprot.txt Reaction=an acyl-CoA + acetyl-CoA = a 3-oxoacyl-CoA + CoA; file:yeast/POT1/POT1-uniprot.txt SIMILARITY: Belongs to the thiolase-like superfamily. Thiolase family. |
| GO:0003988 acetyl-CoA C-acyltransferase activity | IDA PMID:7754706 Purification and immunolocalization of the peroxisomal 3-oxo... | ACCEPT | Summary: Erdmann and Kunau purified the peroxisomal 3-oxoacyl-CoA thiolase from S. cerevisiae as a homodimer. The cached record is abstract-only, but the purification was of the enzyme activity, and an independent preparation (PMID:19470242) confirms thiolytic cleavage by purified ScFox3. This is the core activity. Supporting Evidence: PMID:7754706 Here we describe the isolation of the 3-oxoacyl-CoA thiolase of the peroxisomal beta-oxidation system from Saccharomyces cerevisiae as a dimer of identical subunits PMID:19470242 Purified yeast ScFox3 exhibited thiolase activity that catalyzed the thiolytic cleavage of 3-ketoacyl-CoA to acetyl-CoA and acyl-CoA |
| GO:0003988 acetyl-CoA C-acyltransferase activity | IEA GO_REF:0000120 | ACCEPT | Summary: Combined IEA from RHEA:21564 and EC 2.3.1.16. This is the correct reaction (acyl-CoA + acetyl-CoA = 3-oxoacyl-CoA + CoA) for Pot1p. Supporting Evidence: file:yeast/POT1/POT1-uniprot.txt Reaction=an acyl-CoA + acetyl-CoA = a 3-oxoacyl-CoA + CoA; |
| GO:0003988 acetyl-CoA C-acyltransferase activity | RCA GO_REF:0000123 | ACCEPT | Summary: YeastPathways RCA from YEAST-FAO-PWY (fatty acid oxidation pathway), for the 3-oxoacyl-CoA thiolysis step (EC 2.3.1.16). This is exactly the step Pot1p catalyses. Supporting Evidence: file:yeast/POT1/POT1-uniprot.txt Reaction=an acyl-CoA + acetyl-CoA = a 3-oxoacyl-CoA + CoA; PMID:19470242 Purified yeast ScFox3 exhibited thiolase activity that catalyzed the thiolytic cleavage of 3-ketoacyl-CoA to acetyl-CoA and acyl-CoA |
| GO:0005515 protein binding | IPI PMID:10688190 A comprehensive analysis of protein-protein interactions in ... | REMOVE | Summary: Uetz et al. large-scale Y2H, with PEX7 (P39108). This is the PTS2 cargo-receptor interaction. Physical interaction of the thiolase PTS2 with the PTS2 receptor Pex7p (and/or the Pex21p/Pex18p co-receptor) is real and well characterised, but it is import-cargo recognition: the receptor carries the binding activity and the thiolase is the cargo. 'protein binding' says nothing about thiolase function. No more informative cargo-side MF term exists, so the bare protein-binding row is removed; removal does not mean the interaction is false (the PTS2 import role is captured by the peroxisomal matrix location). Supporting Evidence: PMID:10688190 Two large-scale yeast two-hybrid screens were undertaken to identify protein-protein interactions PMID:23812376 containing Pex7p, the C-terminal region of Pex21p and the PTS2 of the peroxisomal 3-ketoacyl-CoA thiolase |
| GO:0005515 protein binding | IPI PMID:18719252 High-quality binary protein interaction map of the yeast int... | REMOVE | Summary: Yu et al. high-quality binary Y2H map, with PEX7 (P39108). It recapitulates the known PTS2-Pex7p interaction. Physical interaction of the thiolase PTS2 with the PTS2 receptor Pex7p (and/or the Pex21p/Pex18p co-receptor) is real and well characterised, but it is import-cargo recognition: the receptor carries the binding activity and the thiolase is the cargo. 'protein binding' says nothing about thiolase function. No more informative cargo-side MF term exists, so the bare protein-binding row is removed; removal does not mean the interaction is false (the PTS2 import role is captured by the peroxisomal matrix location). Supporting Evidence: PMID:18719252 high-throughput yeast two-hybrid (Y2H) screening provides high-quality binary interaction information PMID:23812376 containing Pex7p, the C-terminal region of Pex21p and the PTS2 of the peroxisomal 3-ketoacyl-CoA thiolase |
| GO:0005515 protein binding | IPI PMID:23812376 Crystal structure of peroxisomal targeting signal-2 bound to... | REMOVE | Summary: Pan et al. crystallised the Pex7p-Pex21p complex bound to the thiolase PTS2 peptide (with PEX7, P39108). This defines PTS2 recognition structurally. Physical interaction of the thiolase PTS2 with the PTS2 receptor Pex7p (and/or the Pex21p/Pex18p co-receptor) is real and well characterised, but it is import-cargo recognition: the receptor carries the binding activity and the thiolase is the cargo. 'protein binding' says nothing about thiolase function. No more informative cargo-side MF term exists, so the bare protein-binding row is removed; removal does not mean the interaction is false (the PTS2 import role is captured by the peroxisomal matrix location). Supporting Evidence: PMID:23812376 containing Pex7p, the C-terminal region of Pex21p and the PTS2 of the peroxisomal 3-ketoacyl-CoA thiolase |
| GO:0005515 protein binding | IPI PMID:23812376 Crystal structure of peroxisomal targeting signal-2 bound to... | REMOVE | Summary: Pan et al. structure of the Pex7p-Pex21p-PTS2 heterotrimer (with PEX21, P50091). The C-terminal region of Pex21p directly contacts the thiolase PTS2 helix. Physical interaction of the thiolase PTS2 with the PTS2 receptor Pex7p (and/or the Pex21p/Pex18p co-receptor) is real and well characterised, but it is import-cargo recognition: the receptor carries the binding activity and the thiolase is the cargo. 'protein binding' says nothing about thiolase function. No more informative cargo-side MF term exists, so the bare protein-binding row is removed; removal does not mean the interaction is false (the PTS2 import role is captured by the peroxisomal matrix location). Supporting Evidence: PMID:23812376 containing Pex7p, the C-terminal region of Pex21p and the PTS2 of the peroxisomal 3-ketoacyl-CoA thiolase |
| GO:0005515 protein binding | IPI PMID:9864360 Pex18p and Pex21p, a novel pair of related peroxins essentia... | REMOVE | Summary: Purdue et al. Y2H with PEX7 (P39108), used as a positive control for the Pex7p bait. The interaction depends on the thiolase PTS2. Physical interaction of the thiolase PTS2 with the PTS2 receptor Pex7p (and/or the Pex21p/Pex18p co-receptor) is real and well characterised, but it is import-cargo recognition: the receptor carries the binding activity and the thiolase is the cargo. 'protein binding' says nothing about thiolase function. No more informative cargo-side MF term exists, so the bare protein-binding row is removed; removal does not mean the interaction is false (the PTS2 import role is captured by the peroxisomal matrix location). Supporting Evidence: PMID:9864360 To validate the usefulness of this bait in PJ69-4A, it was initially tested for interaction with thiolase, which has previously been shown to interact with Pex7p in two-hybrid analyses |
| GO:0005515 protein binding | IPI PMID:9864360 Pex18p and Pex21p, a novel pair of related peroxins essentia... | REMOVE | Summary: Purdue et al. Y2H with PEX21 (P50091). Full-length but not PTS2-truncated thiolase interacted with Pex21p, probably bridged by endogenous Pex7p. Physical interaction of the thiolase PTS2 with the PTS2 receptor Pex7p (and/or the Pex21p/Pex18p co-receptor) is real and well characterised, but it is import-cargo recognition: the receptor carries the binding activity and the thiolase is the cargo. 'protein binding' says nothing about thiolase function. No more informative cargo-side MF term exists, so the bare protein-binding row is removed; removal does not mean the interaction is false (the PTS2 import role is captured by the peroxisomal matrix location). Supporting Evidence: PMID:9864360 full-length thiolase exhibited a clear interaction with Pex18p (Ade+, His+, Ξ²-gal+), and a somewhat lesser interaction with Pex21p (His+, Ξ²-gal+), whereas truncated thiolase showed no interaction |
| GO:0005737 cytoplasm | IEA GO_REF:0000117 | MODIFY | Summary: ARBA-predicted 'cytoplasm'. In GO, the peroxisome lies within the cytoplasm, so the term is not wrong, but it is far less informative than the experimentally established peroxisomal matrix location of this soluble PTS2 cargo. Proposed replacements: peroxisomal matrix Supporting Evidence: PMID:8125978 Saccharomyces cerevisiae peroxisomal 3-ketoacyl-CoA thiolase is a soluble matrix protein |
| GO:0005758 mitochondrial intermembrane space | IDA PMID:22984289 Intermembrane space proteome of yeast mitochondria. | KEEP AS NON CORE | Summary: Vogtle et al. detected Pot1p in their SILAC/Bax-release profile of the mitochondrial intermembrane-space proteome. UniProt records the IMS as a secondary location. The bulk of Pot1p is peroxisomal, and no IMS function is known, so this is retained as a minor, non-core location. The curator's call is respected. Supporting Evidence: PMID:22984289 Considering the 51 proteins in total that are located in the IMS, it is now obvious that the presequence/IMP pathway plays only a minor role in IMS biogenesis. file:yeast/POT1/POT1-uniprot.txt ECO:0000269|PubMed:8125978}. Mitochondrion intermembrane space |
| GO:0005758 mitochondrial intermembrane space | IEA GO_REF:0000044 | KEEP AS NON CORE | Summary: UniProt SubCell SL-0169 mapping, derived from the Vogtle et al. IMS proteome (PMID:22984289). This is a minor secondary location without known function. Non-core. Supporting Evidence: file:yeast/POT1/POT1-uniprot.txt ECO:0000269|PubMed:8125978}. Mitochondrion intermembrane space |
| GO:0005777 peroxisome | EXP PMID:7754706 Purification and immunolocalization of the peroxisomal 3-oxo... | ACCEPT | Summary: Erdmann and Kunau: peroxisomal localisation by subcellular fractionation and immunogold labelling of the purified thiolase. Supporting Evidence: PMID:7754706 its peroxisomal origin was demonstrated by immunoblotting of subcellular fractions as well as by immunogold labelling |
| GO:0005777 peroxisome | EXP PMID:8125978 Mutagenesis of the amino targeting signal of Saccharomyces c... | ACCEPT | Summary: Glover et al.: the N-terminal PTS2 is necessary and sufficient for peroxisomal targeting of thiolase in vivo. Supporting Evidence: PMID:8125978 the amino-terminal 16 amino acids of S. cerevisiae thiolase are necessary and sufficient for targeting to peroxisomes |
| GO:0005777 peroxisome | IBA GO_REF:0000033 | ACCEPT | Summary: IBA (PTN000432379), with POT1 among the experimental descendants. The peroxisomal thiolase clade is correctly inherited, and the location is confirmed experimentally for Pot1p. Supporting Evidence: PMID:7754706 its peroxisomal origin was demonstrated by immunoblotting of subcellular fractions as well as by immunogold labelling |
| GO:0005777 peroxisome | IDA PMID:19470242 Antifungal activity of Saccharomyces cerevisiae peroxisomal ... | ACCEPT | Summary: Lee et al.: ScFox3-GFP localises to peroxisomes, but a PTS2-truncated version does not. Supporting Evidence: PMID:19470242 only ScFox3-GFP, with an intact PTS2 peroxisome signal sequence, was able to translocate into peroxisomes |
| GO:0005777 peroxisome | IEA GO_REF:0000044 | ACCEPT | Summary: UniProt SubCell SL-0204 (Peroxisome). This is correct and consistent with the experimental data. Supporting Evidence: PMID:7754706 its peroxisomal origin was demonstrated by immunoblotting of subcellular fractions as well as by immunogold labelling |
| GO:0005782 peroxisomal matrix | IDA PMID:7754706 Purification and immunolocalization of the peroxisomal 3-oxo... | ACCEPT | Summary: Erdmann and Kunau immunogold labelling places the thiolase within peroxisomes. It is the matrix enzyme of beta-oxidation. Supporting Evidence: PMID:7754706 its peroxisomal origin was demonstrated by immunoblotting of subcellular fractions as well as by immunogold labelling |
| GO:0005782 peroxisomal matrix | IDA PMID:8125978 Mutagenesis of the amino targeting signal of Saccharomyces c... | ACCEPT | Summary: Glover et al. describe thiolase as a soluble peroxisomal matrix protein targeted by its N-terminal PTS2. Supporting Evidence: PMID:8125978 Saccharomyces cerevisiae peroxisomal 3-ketoacyl-CoA thiolase is a soluble matrix protein PMID:8125978 the amino-terminal 16 amino acids of S. cerevisiae thiolase are necessary and sufficient for targeting to peroxisomes |
| GO:0005782 peroxisomal matrix | IMP PMID:8125978 Mutagenesis of the amino targeting signal of Saccharomyces c... | ACCEPT | Summary: Glover et al. mutagenesis of the conserved PTS2 residues abolishes matrix import, which confirms the matrix location. Supporting Evidence: PMID:8125978 the amino-terminal 16 amino acids of S. cerevisiae thiolase are necessary and sufficient for targeting to peroxisomes |
| GO:0005829 cytosol | RCA GO_REF:0000123 | REMOVE | Summary: YeastPathways RCA from YEAST-FAO-PWY assigns the pathway to the cytosol. In S. cerevisiae, fatty acid beta-oxidation is exclusively peroxisomal, and Pot1p is a PTS2-imported matrix enzyme. No evidence places thiolase activity in the cytosol, so this compartment assignment from the pathway conversion is wrong for this protein. Supporting Evidence: PMID:8125978 the amino-terminal 16 amino acids of S. cerevisiae thiolase are necessary and sufficient for targeting to peroxisomes PMID:7754706 its peroxisomal origin was demonstrated by immunoblotting of subcellular fractions as well as by immunogold labelling |
| GO:0006631 fatty acid metabolic process | IEA GO_REF:0000041 | MODIFY | Summary: UniPathway UPA00199 (fatty acid metabolism) mapping. This is correct but too general: Pot1p acts specifically in fatty acid beta-oxidation. Proposed replacements: fatty acid beta-oxidation Supporting Evidence: PMID:12819196 In contrast, polyhydroxyalkanoate containing predominantly 3-hydroxyoctanoate, 3-hydroxydecanoate, and 3-hydroxydodecanoate was synthesized in a mutant deficient in the peroxisomal 3-ketothiolase (fox3 Delta 0) |
| GO:0006635 fatty acid beta-oxidation | IBA GO_REF:0000033 | ACCEPT | Summary: IBA (PTN001823071), with POT1 among the experimental descendants. The thiolase is a catalytic step of the beta-oxidation cycle, so the term is correct. Supporting Evidence: file:yeast/POT1/POT1-uniprot.txt Reaction=an acyl-CoA + acetyl-CoA = a 3-oxoacyl-CoA + CoA; PMID:12819196 In contrast, polyhydroxyalkanoate containing predominantly 3-hydroxyoctanoate, 3-hydroxydecanoate, and 3-hydroxydodecanoate was synthesized in a mutant deficient in the peroxisomal 3-ketothiolase (fox3 Delta 0) |
| GO:0006635 fatty acid beta-oxidation | IMP PMID:12819196 Futile cycling of intermediates of fatty acid biosynthesis t... | ACCEPT | Summary: Marchesini and Poirier: a fox3 (pot1) deletion changes the profile of beta-oxidation intermediates trapped as polyhydroxyalkanoate, consistent with a block at the thiolase step of peroxisomal beta-oxidation. Pot1p catalyses the thiolysis step of the cycle, so it does the work of the process. Supporting Evidence: PMID:12819196 In contrast, polyhydroxyalkanoate containing predominantly 3-hydroxyoctanoate, 3-hydroxydecanoate, and 3-hydroxydodecanoate was synthesized in a mutant deficient in the peroxisomal 3-ketothiolase (fox3 Delta 0) |
| GO:0010124 phenylacetate catabolic process | IBA GO_REF:0000033 | REMOVE | Summary: IBA from PTN001823071. The phenylacetate-catabolism donor is the E. coli PaaJ thiolase (UniProtKB:P0C7L2, 3-oxoadipyl-CoA/3-oxo-5,6-dehydrosuberyl-CoA thiolase). S. cerevisiae has no Paa aerobic phenylacetate ring-cleavage pathway, and no yeast evidence links Pot1p to phenylacetate degradation. Placing this term on a node that spans eukaryotic peroxisomal thiolases over-propagates a bacterium-specific pathway role, so it should not apply to POT1. Propagation Review Root cause: PROPAGATION BAD Failure modes: LINEAGE OR TAXON MISMATCH Sources checked: UniProtKB:P0C7L2 Β· paaJ (E. coli) SUPPORTS SOURCE BUT NOT TARGET Bacterial 3-oxoadipyl-CoA thiolase of the Paa phenylacetate pathway; the pathway is absent from S. cerevisiae. PANTHER:PTN001823071 Β· PTN001823071 UNRESOLVED Node spans bacterial PaaJ and eukaryotic peroxisomal thiolases; the pathway-specific BP should not descend to yeast POT1. Supporting Evidence: file:yeast/POT1/POT1-uniprot.txt Reaction=an acyl-CoA + acetyl-CoA = a 3-oxoacyl-CoA + CoA; file:yeast/POT1/POT1-uniprot.txt SIMILARITY: Belongs to the thiolase-like superfamily. Thiolase family. |
| GO:0016740 transferase activity | IEA GO_REF:0000117 | MODIFY | Summary: ARBA 'transferase activity'. This is correct but uninformative. The specific activity is acetyl-CoA C-acyltransferase (EC 2.3.1.16). Proposed replacements: acetyl-CoA C-acyltransferase activity Supporting Evidence: file:yeast/POT1/POT1-uniprot.txt Reaction=an acyl-CoA + acetyl-CoA = a 3-oxoacyl-CoA + CoA; |
| GO:0016746 acyltransferase activity | IEA GO_REF:0000002 | MODIFY | Summary: InterPro IPR016039 (thiolase-like) mapping to 'acyltransferase activity'. This is correct but too general for this characterised 3-ketoacyl-CoA thiolase. Proposed replacements: acetyl-CoA C-acyltransferase activity Supporting Evidence: file:yeast/POT1/POT1-uniprot.txt Reaction=an acyl-CoA + acetyl-CoA = a 3-oxoacyl-CoA + CoA; |
| GO:0016747 acyltransferase activity, transferring groups other than amino-acyl groups | IEA GO_REF:0000002 | MODIFY | Summary: InterPro thiolase signatures (IPR002155, IPR020610, IPR020613, IPR020615-7) mapping to the generic acyltransferase parent. The precise activity is acetyl-CoA C-acyltransferase. Proposed replacements: acetyl-CoA C-acyltransferase activity Supporting Evidence: file:yeast/POT1/POT1-uniprot.txt Reaction=an acyl-CoA + acetyl-CoA = a 3-oxoacyl-CoA + CoA; |
| GO:0019395 fatty acid oxidation | RCA GO_REF:0000123 | MODIFY | Summary: YeastPathways RCA from YEAST-FAO-PWY (fatty acid oxidation). This is correct, but fatty acid beta-oxidation (a child term) describes the Pot1p step more precisely. Proposed replacements: fatty acid beta-oxidation Supporting Evidence: PMID:12819196 In contrast, polyhydroxyalkanoate containing predominantly 3-hydroxyoctanoate, 3-hydroxydecanoate, and 3-hydroxydodecanoate was synthesized in a mutant deficient in the peroxisomal 3-ketothiolase (fox3 Delta 0) |
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Download this section (compressed HTML)Q: Does the small pool of Pot1p detected in the mitochondrial intermembrane space have a physiological role, or is it a mistargeting/contamination artefact of the proteomic profiling?
Q: Is the mRNA binding of Pot1p (enriched for translation-related messages) functionally relevant, for example for oleate-induced post-transcriptional regulation?
Experiment: Express a PTS2-deleted Pot1p that is retargeted to the IMS (or a variant that excludes it from the IMS) in a pot1 deletion strain, and test growth on oleate and acyl-CoA profiles.
Hypothesis: The IMS-localised Pot1p pool is functionally relevant
Type: genetic / localisation
3-ketoacyl-CoA thiolase with broad chain length specificity; cleaves 3-ketoacyl-CoA into acyl-CoA and acetyl-CoA during beta-oxidation of fatty acids
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