coq3 encodes the fission yeast Coq3 O-methyltransferase, a SAM-dependent enzyme of the UbiG/COQ3 family that performs both O-methylations of the coenzyme Q10 ring: the methylation of 3,4-dihydroxy-5-decaprenylbenzoate and, as the final step of the pathway, the methylation of 3-demethylubiquinol (or -ubiquinone) to ubiquinol-10. It is a peripheral protein on the matrix side of the mitochondrial inner membrane, part of the multi-subunit CoQ biosynthetic complex. Deletion of coq3 abolishes CoQ10 synthesis; human COQ3 complements only when given a mitochondrial targeting sequence, and Arabidopsis COQ3 also complements.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0005739 mitochondrion | HDA PMID:16823372 ORFeome cloning and global analysis of protein localization ... | ACCEPT | Summary: ORFeome YFP screen: mitochondrion. Reason: Genome-wide YFP-tagging screen (HDA) placed Coq3 in mitochondria, in agreement with the single-gene Coq3-GFP/MitoTracker result (PMID:24911838). Direct evidence from an assay that cannot resolve the sub-compartment: ACCEPT at the root organelle term. Supporting Evidence: PMID:16823372 we determined the localization of 4,431 proteins, corresponding to approximately 90% of the fission yeast proteome, by tagging each ORF with the yellow fluorescent protein PMID:24911838 These results are consistent with those of a previous study [44] that examined the localization of 4,431 S. pombe proteins |
| GO:0005739 mitochondrion | IBA GO_REF:0000033 | ACCEPT | Summary: PAINT inference of mitochondrial location. Reason: IBA from PAINT node PTN000566263 (PTHR43464, GO_REF:0000033). Mitochondrial location of S. pombe Coq3 is shown directly: Coq3-GFP expressed in the deletion strain localised to mitochondria (Hayashi et al. 2014), and the curated UniProt location (inner membrane, PubMed:24911838) entails the mitochondrion. The PAINT node therefore agrees with the experimental data on the gene itself. Supporting Evidence: PMID:24911838 The Dps1, Ppt1/Coq2, Coq3, Coq4, Coq5, Coq6, Coq7, Coq8, and Coq9 GFP fusion proteins also localized to the mitochondria file:SCHPO/coq3/coq3-uniprot.txt SUBCELLULAR LOCATION: Mitochondrion inner membrane |
| GO:0005739 mitochondrion | IDA PMID:24911838 Functional conservation of coenzyme Q biosynthetic genes amo... | ACCEPT | Summary: Mitochondrial localisation of the tagged protein. Reason: Coq3-GFP expressed in the corresponding deletion strain localises to MitoTracker-stained mitochondria (PMID:24911838). Whole-organelle co-staining: ACCEPT at the root organelle term. Supporting Evidence: PMID:24911838 The Dps1, Ppt1/Coq2, Coq3, Coq4, Coq5, Coq6, Coq7, Coq8, and Coq9 GFP fusion proteins also localized to the mitochondria PMID:24911838 The results presented here demonstrate that all of the S. pombe Coq proteins localize to mitochondria, indicating that CoQ biosynthesis occurs in these cellular compartments. |
| GO:0005743 mitochondrial inner membrane | EXP PMID:24911838 Functional conservation of coenzyme Q biosynthetic genes amo... | ACCEPT | Summary: PomBase EXP for inner-membrane location from the systematic S. pombe coq study. Reason: The cached full text of PMID:24911838 localises Coq3-GFP to mitochondria by co-staining and reports no sub-mitochondrial fractionation, so the inner-membrane resolution is the curator's (and UniProt's, which tags the line with this paper and HAMAP MF_03190). The claim is consistent with the S. cerevisiae ortholog, whose inner-membrane IDA rows are accepted in the COQ3 review, and with Coq3 acting on membrane-embedded prenylated intermediates; accepted, not second-guessed. Supporting Evidence: PMID:24911838 The Dps1, Ppt1/Coq2, Coq3, Coq4, Coq5, Coq6, Coq7, Coq8, and Coq9 GFP fusion proteins also localized to the mitochondria file:SCHPO/coq3/coq3-uniprot.txt SUBCELLULAR LOCATION: Mitochondrion inner membrane {ECO:0000255|HAMAP-Rule:MF_03190, ECO:0000269|PubMed:24911838}; Peripheral membrane protein |
| GO:0005743 mitochondrial inner membrane | IEA GO_REF:0000044 | ACCEPT | Summary: UniProt mapping; consistent. Reason: This IEA is the UniProt SubCell mapping of the curated location line, which cites PubMed:24911838 and HAMAP rule MF_03190. The GFP assay in that paper resolves only the mitochondrion; the inner-membrane (matrix-side peripheral) placement rests on the HAMAP rule, i.e. on the Coq3 orthologs of the CoQ synthome. Consistent with the EXP row. Supporting Evidence: file:SCHPO/coq3/coq3-uniprot.txt SUBCELLULAR LOCATION: Mitochondrion inner membrane |
| GO:0006744 ubiquinone biosynthetic process | IBA GO_REF:0000033 | ACCEPT | Summary: PAINT inference; ubiquinone biosynthesis step. Reason: IBA from PAINT node PTN000566263 (PTHR43464, GO_REF:0000033). Supported by experimental data on the gene itself: the S. pombe coq3 deletion cannot make CoQ10, and human and Arabidopsis COQ3 restore CoQ10 production in it (Hayashi et al. 2014); the UniProt PATHWAY line carries ECO:0000269 to that paper. Supporting Evidence: PMID:24911838 Δcoq3 [22], Δcoq7 [22], and Δcoq8 [27] strains, which are unable to synthesize CoQ PMID:24911838 Targeting of HsCOQ3 and HsCOQ7 to the mitochondria successfully recovered defective CoQ10 production by the S. pombe Δcoq3 (Figure 6C) and Δcoq7 (Figure 7A) strains. file:SCHPO/coq3/coq3-uniprot.txt Cofactor biosynthesis; ubiquinone biosynthesis. |
| GO:0006744 ubiquinone biosynthetic process | IEA GO_REF:0000120 | ACCEPT | Summary: Mapping; consistent. Reason: UniRule/InterPro/UniPathway mapping (GO_REF:0000120). Same claim as the IBA and IMP rows; the UniProt PATHWAY line carries ECO:0000269 to Hayashi et al. 2014, where the coq3 deletion cannot make CoQ10. Supporting Evidence: PMID:24911838 Δcoq3 [22], Δcoq7 [22], and Δcoq8 [27] strains, which are unable to synthesize CoQ file:SCHPO/coq3/coq3-uniprot.txt Cofactor biosynthesis; ubiquinone biosynthesis. |
| GO:0006744 ubiquinone biosynthetic process | IMP PMID:24911838 Functional conservation of coenzyme Q biosynthetic genes amo... | ACCEPT | Summary: Deletion abolishes CoQ10 production (systematic analysis of the S. pombe coq genes). Reason: Deletion of the gene abolishes CoQ10 synthesis and gives the shared coq-mutant phenotypes (PMID:24911838). Coq3 performs a step of the pathway, so it does part of the work; core process. Supporting Evidence: PMID:24911838 Here, we expand these findings by identifying ten genes (dps1, dlp1, ppt1, and coq3-9) that are required for CoQ synthesis. PMID:24911838 Overall, these data indicate that, like the S. pombe Δdps1, Δdlp1, Δppt1/coq2, Δcoq3, Δcoq7, and Δcoq8 strains described previously, the Δcoq4, Δcoq5, Δcoq6, and Δcoq9 strains are also unable to synthesize CoQ. |
| GO:0010420 polyprenyldihydroxybenzoate methyltransferase activity | IBA GO_REF:0000033 | ACCEPT | Summary: First O-methylation (PAINT/EC). Reason: IBA from PAINT node PTN000566263 (PTHR43464, GO_REF:0000033). No S. pombe enzymology exists. Support is the curated HAMAP rule MF_03190 (UbiG/COQ3 family) in UniProt, which assigns the first O-methylation (EC 2.1.1.114), together with functional complementation of the coq3 deletion by Arabidopsis COQ3 in Hayashi et al. 2014, which shows the S. pombe protein performs the COQ3 step in vivo. Core function, consistent with the S. cerevisiae COQ3 review. Supporting Evidence: file:SCHPO/coq3/coq3-uniprot.txt Catalyzes the 2 O-methylation of 3,4-dihydroxy-5-(all-trans-decaprenyl)benzoic acid into 4-hydroxy-3-methoxy-5-(all-trans-decaprenyl)benzoic acid file:SCHPO/coq3/coq3-uniprot.txt Belongs to the class I-like SAM-binding methyltransferase superfamily. UbiG/COQ3 family. PMID:24911838 Expression of AtCOQ3, AtCOQ4 and AtCOQ5 recovered CoQ10 production by the S. pombe Δcoq3, Δcoq4 and Δcoq5 strains, respectively (Figures 9A–C). |
| GO:0010420 polyprenyldihydroxybenzoate methyltransferase activity | IEA GO_REF:0000120 | ACCEPT | Summary: First O-methylation (PAINT/EC). Reason: UniRule/InterPro mapping (GO_REF:0000120). Same claim as the IBA row: the HAMAP rule MF_03190 (UbiG/COQ3 family) assigns the first O-methylation; there is no direct S. pombe enzymology, but cross-species complementation of the coq3 deletion (Hayashi et al. 2014) supports the conserved COQ3 role. Core function. Supporting Evidence: file:SCHPO/coq3/coq3-uniprot.txt Catalyzes the 2 O-methylation of 3,4-dihydroxy-5-(all-trans-decaprenyl)benzoic acid into 4-hydroxy-3-methoxy-5-(all-trans-decaprenyl)benzoic acid file:SCHPO/coq3/coq3-uniprot.txt NCBIfam; TIGR01983; UbiG; 1. |
| GO:0031314 extrinsic component of mitochondrial inner membrane | IC GO_REF:0000111 | ACCEPT | Summary: Peripheral component on the matrix side of the inner membrane, where the CoQ synthome assembles. Reason: UniProt places Coq3 on the matrix side of the inner membrane as a peripheral membrane protein (HAMAP MF_03190, with mitochondrial location from PubMed:24911838). Peripheral, matrix-side placement rests on the CoQ synthome orthologs rather than on an S. pombe sub-mitochondrial assay; the record has a transit peptide (FT TRANSIT 1..30) and no TRANSMEM feature, consistent with a peripheral rather than integral protein. The S. cerevisiae ortholog carries IDA support for this term (COQ3 review). Accepted as the sub-compartment where the CoQ synthome acts. Supporting Evidence: file:SCHPO/coq3/coq3-uniprot.txt Mitochondrion inner membrane; Peripheral membrane protein; Matrix side |
| GO:0031314 extrinsic component of mitochondrial inner membrane | IEA GO_REF:0000104 | ACCEPT | Summary: Peripheral component on the matrix side of the inner membrane, where the CoQ synthome assembles. Reason: UniRule mapping (GO_REF:0000104). Same claim as the IC row: UniProt places Coq3 as a peripheral membrane protein on the matrix side of the inner membrane (HAMAP MF_03190); the record has no TRANSMEM feature. The topology rests on the orthologous CoQ synthome, not on an S. pombe sub-mitochondrial assay. Supporting Evidence: file:SCHPO/coq3/coq3-uniprot.txt Mitochondrion inner membrane; Peripheral membrane protein; Matrix side |
| GO:0061542 3-demethylubiquinol 3-O-methyltransferase activity | IEA GO_REF:0000120 | ACCEPT | Summary: Final O-methylation of 3-demethylubiquinol (EC/RHEA). Reason: UniRule/InterPro mapping (GO_REF:0000120). No S. pombe enzymology exists. The curated HAMAP rule MF_03190 for the UbiG/COQ3 family assigns the final O-methylation, including methylation of 3-demethylubiquinol-10 (EC 2.1.1.64); complementation of the coq3 deletion by human and Arabidopsis COQ3 (Hayashi et al. 2014) supports the conserved COQ3 role in vivo. Core function (the final O-methylation), consistent with the S. cerevisiae COQ3 review and the module annoton. Supporting Evidence: file:SCHPO/coq3/coq3-uniprot.txt Also able to mediate the methylation of 3-demethylubiquinol-10 into ubiquinol-10 file:SCHPO/coq3/coq3-uniprot.txt Belongs to the class I-like SAM-binding methyltransferase superfamily. UbiG/COQ3 family. |
| GO:0120537 3-demethylubiquinone 3-O-methyltransferase activity | IEA GO_REF:0000116 | ACCEPT | Summary: Final O-methylation written for the quinone form (3-demethylubiquinone to ubiquinone); HAMAP MF_03190 curates both redox forms. Reason: Rule-based mapping (GO_REF:0000116, Rhea RHEA:81215). The HAMAP COQ3 rule (MF_03190) curates both the quinone and quinol forms of the last methylation step, and which redox form Coq3 acts on in vivo is not resolved; the term is a true description of the final O-methylation and is accepted alongside GO:0061542, consistent with the S. cerevisiae COQ3 review, where both terms are accepted. No S. pombe enzyme assay exists; support is family-rule plus complementation by human and Arabidopsis COQ3 (PMID:24911838). Supporting Evidence: file:SCHPO/coq3/coq3-uniprot.txt Also catalyzes the last step of ubiquinone biosynthesis by mediating methylation of 3-demethylubiquinone into ubiquinone. file:SCHPO/coq3/coq3-uniprot.txt Reaction=a 3-demethylubiquinone + S-adenosyl-L-methionine = a ubiquinone + S-adenosyl-L-homocysteine PMID:24911838 Targeting of HsCOQ3 and HsCOQ7 to the mitochondria successfully recovered defective CoQ10 production by the S. pombe Δcoq3 (Figure 6C) and Δcoq7 (Figure 7A) strains. |
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