CAB5 (YDR196C) encodes the essential dephospho-CoA kinase (DPCK) of S. cerevisiae, a CoaE-family P-loop kinase that phosphorylates the 3'-hydroxyl of the ribose of 3'-dephospho-CoA using ATP to form coenzyme A, the final (fifth) step of CoA biosynthesis. The null is lethal and is complemented by E. coli coaE and by human COASY. Cab5 is a component of the CoA-synthesizing protein complex (CoA-SPC) through binding to the N-terminus of Cab3, and fractionation and protease-protection experiments show that most Cab5 is associated with mitochondria as an extrinsic protein of the outer membrane, facing the cytosol. High-throughput studies additionally detect it at the ER, nuclear envelope and lipid droplets. A Cab5 R146C mutation modelling human COASY-associated neurodegeneration (CoPAN) reduces mitochondrial CoA and causes iron and lipid phenotypes.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0004140 dephospho-CoA kinase activity | IBA GO_REF:0000033 | ACCEPT | Summary: IBA (PTN000075336; E. coli CoaE, mouse Coasy, Arabidopsis DPCK). Cab5 is the CoaE-family member in yeast; core MF. Supporting Evidence: file:yeast/CAB5/CAB5-uniprot.txt SIMILARITY: Belongs to the CoaE family. {ECO:0000305}. PMID:19266201 Null mutants could be complemented by their bacterial counterparts coaBC, coaD and coaE, respectively. |
| GO:0004140 dephospho-CoA kinase activity | IEA GO_REF:0000120 | ACCEPT | Summary: IEA from InterPro IPR001977 (dephospho-CoA kinase) / RHEA:18245 / EC 2.7.1.24. Correct. Supporting Evidence: file:yeast/CAB5/CAB5-uniprot.txt Reaction=3'-dephospho-CoA + ATP = ADP + CoA + H(+); |
| GO:0004140 dephospho-CoA kinase activity | ISS PMID:10592175 The COG database: a tool for genome-scale analysis of protei... | ACCEPT | Summary: ISS from E. coli CoaE (P0A6I9) citing the COG database. Correct by homology; complementation of the null by coaE (Olzhausen et al. 2009) supports it. Supporting Evidence: PMID:19266201 Null mutants could be complemented by their bacterial counterparts coaBC, coaD and coaE, respectively. |
| GO:0004140 dephospho-CoA kinase activity | RCA GO_REF:0000123 | ACCEPT | Summary: RCA from YeastPathways PANTOSYN2-PWY assigning Cab5 to 3'-dephospho-CoA + ATP -> CoA + ADP (EC 2.7.1.24). Correct. Supporting Evidence: file:yeast/CAB5/CAB5-uniprot.txt Reaction=3'-dephospho-CoA + ATP = ADP + CoA + H(+); |
| GO:0005515 protein binding | IPI PMID:23789928 Molecular characterization of the heteromeric coenzyme A-syn... | REMOVE | Summary: IPI with Cab3 (P36076) (Olzhausen et al. 2013). 'Protein binding' conveys no functional information; the biologically meaningful content of Cab-protein interactions is captured by CoA-synthesizing protein complex (GO:1990143) / PPCDC complex (GO:0071513) membership. Reason: Uninformative 'protein binding' term; interaction is not disputed but is better represented by complex membership. |
| GO:0005515 protein binding | IPI PMID:23789928 Molecular characterization of the heteromeric coenzyme A-syn... | REMOVE | Summary: IPI with Cab4 (P53332) (Olzhausen et al. 2013). 'Protein binding' conveys no functional information; the biologically meaningful content of Cab-protein interactions is captured by CoA-synthesizing protein complex (GO:1990143) / PPCDC complex (GO:0071513) membership. Reason: Uninformative 'protein binding' term; interaction is not disputed but is better represented by complex membership. |
| GO:0005524 ATP binding | IEA GO_REF:0000002 | KEEP AS NON CORE | Summary: IEA from InterPro IPR001977. ATP is the phosphate donor; correct but implied by the kinase activity. Reason: Substrate binding implied by the catalytic activity. Supporting Evidence: file:yeast/CAB5/CAB5-uniprot.txt Reaction=3'-dephospho-CoA + ATP = ADP + CoA + H(+); |
| GO:0005634 nucleus | EXP PMID:14690591 Assigning function to yeast proteins by integration of techn... | KEEP AS NON CORE | Summary: EXP (Hazbun et al. 2003 essential-ORF imaging) for nucleus. No nuclear function known; dedicated fractionation (Ceccatelli Berti et al. 2015) places most Cab5 on mitochondria. Reason: High-throughput observation without functional support. Supporting Evidence: PMID:14690591 fluorescence microscopy to localize the proteins |
| GO:0005634 nucleus | IEA GO_REF:0000044 | KEEP AS NON CORE | Summary: IEA from UniProt subcellular location (Nucleus). Same high-throughput basis. Reason: High-throughput localisation only. |
| GO:0005635 nuclear envelope | HDA PMID:14690591 Assigning function to yeast proteins by integration of techn... | KEEP AS NON CORE | Summary: HDA (Hazbun et al. 2003) nuclear envelope signal. Possibly reflects membrane association seen by imaging; no functional significance known. Reason: High-throughput observation. |
| GO:0005737 cytoplasm | IEA GO_REF:0000117 | ACCEPT | Summary: IEA from ARBA (cytoplasm). Cab5 acts on the cytosolic face of the mitochondrial outer membrane and associates with the cytosolic CoA-SPC, so cytoplasm is correct at a general level. Supporting Evidence: PMID:28357284 Taken together these results suggest that Cab5 is an extrinsic outer membrane protein |
| GO:0005739 mitochondrion | EXP PMID:14690591 Assigning function to yeast proteins by integration of techn... | ACCEPT | Summary: EXP (Hazbun et al. 2003) mitochondrion. Confirmed by subcellular fractionation (Ceccatelli Berti et al. 2015). Supporting Evidence: PMID:28357284 The great majority of Cab5-HA co-fractionated with the mitochondrial membrane protein porin |
| GO:0005739 mitochondrion | HDA PMID:16823961 Toward the complete yeast mitochondrial proteome: multidimen... | ACCEPT | Summary: HDA (Reinders et al. 2006 mitochondrial proteome). Consistent with Cab5 being peripherally bound to mitochondria. Supporting Evidence: PMID:28357284 The great majority of Cab5-HA co-fractionated with the mitochondrial membrane protein porin |
| GO:0005739 mitochondrion | IEA GO_REF:0000044 | ACCEPT | Summary: IEA from UniProt subcellular location (Mitochondrion). Correct. Supporting Evidence: PMID:28357284 The great majority of Cab5-HA co-fractionated with the mitochondrial membrane protein porin |
| GO:0005783 endoplasmic reticulum | HDA PMID:14690591 Assigning function to yeast proteins by integration of techn... | KEEP AS NON CORE | Summary: HDA (Hazbun et al. 2003) ER localisation from imaging. Not supported by dedicated fractionation, which shows mitochondrial outer membrane association; kept as an observed, non-core location. Reason: High-throughput imaging only. |
| GO:0005783 endoplasmic reticulum | IEA GO_REF:0000044 | KEEP AS NON CORE | Summary: IEA from UniProt subcellular location (ER), derived from the same imaging data. Reason: High-throughput imaging only. |
| GO:0005811 lipid droplet | IDA PMID:24868093 High confidence proteomic analysis of yeast LDs identifies a... | KEEP AS NON CORE | Summary: IDA (Currie et al. 2014 high-confidence lipid droplet proteome). Detected in purified lipid droplets; no LD-specific function known. Reason: Proteomic detection without known function at lipid droplets. |
| GO:0005829 cytosol | HDA PMID:26928762 One library to make them all: streamlining the creation of y... | ACCEPT | Summary: HDA (Yofe et al. 2016 SWAT library imaging). Cab5 faces the cytosol at the mitochondrial outer membrane and associates with the cytosolic CoA-SPC. Supporting Evidence: PMID:28357284 Taken together these results suggest that Cab5 is an extrinsic outer membrane protein |
| GO:0005829 cytosol | RCA GO_REF:0000123 | ACCEPT | Summary: RCA from YeastPathways PANTOSYN2-PWY (cytosolic step). Acceptable; the enzyme is extrinsic on the cytosolic face of the mitochondrial outer membrane. |
| GO:0015937 coenzyme A biosynthetic process | IBA GO_REF:0000033 | ACCEPT | Summary: IBA (PTN000075336). DPCK catalyses the final step of CoA biosynthesis. Core BP. Supporting Evidence: PMID:19266201 Similar to CAB1, genes YIL083C, YKL088W, YGR277C and YDR106C responsible for late CoA biosynthesis turned out as essential. |
| GO:0015937 coenzyme A biosynthetic process | IEA GO_REF:0000120 | ACCEPT | Summary: IEA from ARBA / InterPro IPR001977 / UniPathway UPA00241. Correct. Supporting Evidence: file:yeast/CAB5/CAB5-uniprot.txt Reaction=3'-dephospho-CoA + ATP = ADP + CoA + H(+); |
| GO:0015937 coenzyme A biosynthetic process | IGI PMID:19266201 Genetic analysis of coenzyme A biosynthesis in the yeast Sac... | ACCEPT | Summary: IGI (Olzhausen et al. 2009) with E. coli coaE (P0A6I9): bacterial DPCK complements the essential YDR196C null. Supporting Evidence: PMID:19266201 Similar to CAB1, genes YIL083C, YKL088W, YGR277C and YDR106C responsible for late CoA biosynthesis turned out as essential. PMID:19266201 Null mutants could be complemented by their bacterial counterparts coaBC, coaD and coaE, respectively. |
| GO:0015937 coenzyme A biosynthetic process | NAS PMID:19266201 Genetic analysis of coenzyme A biosynthesis in the yeast Sac... | ACCEPT | Summary: NAS (Olzhausen et al. 2009). Correct; redundant. Supporting Evidence: PMID:19266201 Similar to CAB1, genes YIL083C, YKL088W, YGR277C and YDR106C responsible for late CoA biosynthesis turned out as essential. |
| GO:0015937 coenzyme A biosynthetic process | RCA GO_REF:0000123 | ACCEPT | Summary: RCA from YeastPathways PANTOSYN2-PWY. Correct. |
| GO:0031315 extrinsic component of mitochondrial outer membrane | IDA PMID:28357284 Modeling human Coenzyme A synthase mutation in yeast reveals... | ACCEPT | Summary: IDA (Ceccatelli Berti et al. 2015): Cab5-HA co-fractionates with mitochondria and is highly protease-sensitive in intact mitochondria, indicating an extrinsic outer membrane protein. This is the best-supported specific location. Supporting Evidence: PMID:28357284 The great majority of Cab5-HA co-fractionated with the mitochondrial membrane protein porin PMID:28357284 Taken together these results suggest that Cab5 is an extrinsic outer membrane protein |
| GO:1990143 CoA-synthesizing protein complex | IDA PMID:23789928 Molecular characterization of the heteromeric coenzyme A-syn... | ACCEPT | Summary: IDA (Olzhausen et al. 2013): Cab5 co-fractionates with Cab3 in a ~330 kDa complex. Supporting Evidence: PMID:23789928 Using epitope-tagged variants of Cab3 and Cab5, we show that both proteins cofractionate upon chromatographic separation, forming a complex of about 330 kDa. PMID:23789928 Mapping studies revealed that the nonconserved N-terminus of Cab3 is required for dimerization and for binding of Cab2 and Cab5. |
| GO:1990143 CoA-synthesizing protein complex | NAS PMID:23789928 Molecular characterization of the heteromeric coenzyme A-syn... | ACCEPT | Summary: NAS (Olzhausen et al. 2013). Correct; redundant. Supporting Evidence: PMID:23789928 Our interaction studies confirm early reports on the existence of a CoA-synthesizing protein complex (CoA-SPC) in yeast |
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Experiment: Co-fractionation/proximity labelling of Cab2-Cab4 with mitochondria to test whether the whole CoA-SPC is recruited to the outer membrane via Cab5.
Subunit of the CoA-Synthesizing Protein Complex (CoA-SPC); subunits of this complex are: Cab2p, Cab3p, Cab4p, Cab5p, Sis2p and Vhs3p; probable dephospho-CoA kinase (DPCK) that catalyzes the last step in coenzyme A biosynthesis; involved in histone acylation; null mutant lethality is complemented by human homologs DCAKD and COASY and by E. coli coaE (encoding DPCK); extrinsic component of the mitochondrial outer membrane that also localizes to lipid droplets
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