SPS19 encodes the peroxisomal 2,4-dienoyl-CoA reductase of S. cerevisiae (NADPH-dependent, (3E)-enoyl-CoA-producing; EC 1.3.1.124), a short-chain dehydrogenase/reductase family homodimer imported into the peroxisomal matrix via a C-terminal SKL PTS1. It is an auxiliary enzyme of peroxisomal fatty acid beta-oxidation required to degrade unsaturated fatty acids with double bonds at even-numbered positions: it reduces 2,4-dienoyl-CoA intermediates with NADPH to 3-enoyl-CoA, which the delta3-delta2-enoyl-CoA isomerase Eci1p then returns to the core beta-oxidation spiral. sps19 deletion mutants grow normally on oleate (cis-9) but cannot use petroselinate (cis-6). SPS19 is strongly induced by oleate through an oleate response element shared with the divergently transcribed sporulation gene SPS18, and is also weakly induced late in sporulation, but it is dispensable for sporulation on acetate.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0005777 peroxisome | IBA GO_REF:0000033 | ACCEPT | Summary: PAINT IBA for peroxisomal activity of the DECR2 clade (SGD SPS19 itself among the sources). Correct; Sps19p is in the peroxisomal matrix. Supporting Evidence: PMID:9268358 Antibodies raised against Sps19p decorated the peroxisomal matrix of oleate-induced cells. |
| GO:0005777 peroxisome | IEA GO_REF:0000044 | ACCEPT | Summary: UniProt subcellular-location mapping to peroxisome. Correct. Supporting Evidence: file:yeast/SPS19/SPS19-uniprot.txt SUBCELLULAR LOCATION: Peroxisome |
| GO:0005782 peroxisomal matrix | IDA PMID:9268358 The Saccharomyces cerevisiae peroxisomal 2,4-dienoyl-CoA red... | ACCEPT | Summary: Immunolabelling of oleate-induced cells localised Sps19p to the peroxisomal matrix. Correct and the most specific location. Supporting Evidence: PMID:9268358 Antibodies raised against Sps19p decorated the peroxisomal matrix of oleate-induced cells. PMID:7969036 which has a peroxisomal targeting signal (SKL) at its C terminus |
| GO:0006631 fatty acid metabolic process | IBA GO_REF:0000033 | TOO GENERAL | Summary: PAINT IBA for 'fatty acid metabolic process'. Correct but broad; Sps19p acts specifically in beta-oxidation of unsaturated fatty acids, already captured by the fatty acid catabolic process annotations. Reason: Broad ancestor of the catabolic/beta-oxidation role. Supporting Evidence: file:yeast/SPS19/SPS19-uniprot.txt Auxiliary enzyme of beta-oxidation. |
| GO:0008670 2,4-dienoyl-CoA reductase (NADPH) activity | IBA GO_REF:0000033 | ACCEPT | Summary: PAINT IBA for 2,4-dienoyl-CoA reductase (NADPH) activity, with SPS19 itself among the experimental sources. Correct. Supporting Evidence: PMID:9268358 the homodimeric enzyme (native molecular weight 69,000) converted 2,4-hexadienoyl-CoA into 3-hexenoyl-CoA in an NADPH-dependent manner and therefore contained 2,4-dienoyl-CoA reductase activity. |
| GO:0008670 2,4-dienoyl-CoA reductase (NADPH) activity | IDA PMID:9268358 The Saccharomyces cerevisiae peroxisomal 2,4-dienoyl-CoA red... | ACCEPT | Summary: Purified Sps19p reduced 2,4-hexadienoyl-CoA to 3-hexenoyl-CoA with NADPH. Core activity. Supporting Evidence: PMID:9268358 the homodimeric enzyme (native molecular weight 69,000) converted 2,4-hexadienoyl-CoA into 3-hexenoyl-CoA in an NADPH-dependent manner and therefore contained 2,4-dienoyl-CoA reductase activity. |
| GO:0008670 2,4-dienoyl-CoA reductase (NADPH) activity | IEA GO_REF:0000002 | ACCEPT | Summary: InterPro2GO (DECR2-like, IPR045017) mapping to 2,4-dienoyl-CoA reductase (NADPH) activity. Correct. Supporting Evidence: PMID:9268358 the homodimeric enzyme (native molecular weight 69,000) converted 2,4-hexadienoyl-CoA into 3-hexenoyl-CoA in an NADPH-dependent manner and therefore contained 2,4-dienoyl-CoA reductase activity. |
| GO:0009062 fatty acid catabolic process | IDA PMID:9268358 The Saccharomyces cerevisiae peroxisomal 2,4-dienoyl-CoA red... | ACCEPT | Summary: sps19 deletion prevents use of petroselinate (cis-C18:1(6)) as sole carbon source while oleate use is normal, showing Sps19p is required for catabolism of fatty acids with even-numbered double bonds. Supporting Evidence: PMID:9268358 an SPS19 deleted strain was unable to utilize petroselineate (cis-C18:1(6)) as the sole carbon source, but remained viable on oleate (cis-C18:1(9)). PMID:9268358 Fatty acids with double bonds at even-numbered positions require for their degradation the auxiliary enzyme 2,4-dienoyl-CoA reductase |
| GO:0009062 fatty acid catabolic process | IEA GO_REF:0000002 | ACCEPT | Summary: InterPro2GO mapping to fatty acid catabolic process. Correct; Sps19p is needed to degrade fatty acids with even-position double bonds. Supporting Evidence: PMID:9268358 an SPS19 deleted strain was unable to utilize petroselineate (cis-C18:1(6)) as the sole carbon source, but remained viable on oleate (cis-C18:1(9)). |
| GO:0030437 ascospore formation | IMP PMID:7969036 Identification of a sporulation-specific promoter regulating... | MARK AS OVER ANNOTATED | Summary: Coe et al. deleted the intergenic promoter shared by SPS18 and SPS19, abolishing expression of both genes; the four-fold sporulation defect (spore wall maturation) cannot be assigned to SPS19. Later work showed that SPS19 itself is dispensable for sporulation on acetate and needed only when petroselinate is the carbon source, i.e. for fatty acid utilisation rather than spore formation. Reason: The mutation removed expression of both SPS18 and SPS19; an sps19-specific deletion sporulates normally on acetate, so ascospore formation is not a function of Sps19p. Supporting Evidence: PMID:7969036 A null mutation deleting the intergenic promoter prevented expression of both genes, and when homozygous in diploids, reduced the extent of sporulation four-fold PMID:9268358 SPS19 is dispensable for growth and sporulation on solid acetate and oleate media, but is essential for these processes to occur on petroselineate. |
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Download this section (compressed HTML)Q: Should GO provide an unsaturated-fatty-acid beta-oxidation process term (cf. MetaCyc 'oleate beta-oxidation' / even-position double-bond degradation), so that auxiliary enzymes such as Sps19p and Eci1p can be annotated more specifically than 'fatty acid catabolic process'?
Experiment: Test sporulation of an sps19 single deletion (with SPS18 intact) and of an sps18 single deletion to assign the spore-wall maturation defect of the shared-promoter deletion to the correct gene.
Peroxisomal 2,4-dienoyl-CoA reductase; auxiliary enzyme of fatty acid beta-oxidation; homodimeric enzyme required for growth and sporulation on petroselineate medium; expression induced during late sporulation and in the presence of oleate
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