Fatty acid elongase 1 (Elo1/YJL196C) is the medium-chain member of the three ER-resident ELO-family condensing enzymes of Saccharomyces cerevisiae. It catalyses the rate-limiting condensation of acyl-CoA with malonyl-CoA (EC 2.3.1.199) as the first step of the ER fatty acid elongation cycle (with the shared Ifa38 ketoreductase, Phs1 dehydratase and Tsc13 enoyl reductase). Elo1 defines elongase I, which extends C12-C16 saturated and monounsaturated acyl-CoAs (e.g. C14:0, C14:1 delta9) to C16-C18 products by carboxy-terminal (alpha) elongation; it is dispensable for VLCFA synthesis, which is performed by its paralogs Elo2 and Elo3. ELO1 is induced by exogenous myristate and is a multi-pass integral ER membrane protein.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0005783 endoplasmic reticulum | HDA PMID:26928762 One library to make them all: streamlining the creation of y... | ACCEPT | Summary: High-throughput N-terminal SWAT-GFP localization places Elo1 in the ER, consistent with the C-terminal di-lysine ER retention motif and multi-pass topology of ELO-family elongases. Correct, though ER membrane is the more precise compartment. Supporting Evidence: file:yeast/ELO1/ELO1-uniprot.txt SUBCELLULAR LOCATION: Endoplasmic reticulum membrane |
| GO:0005783 endoplasmic reticulum | IEA GO_REF:0000117 | ACCEPT | Summary: ARBA rule assigns ER to ELO-family proteins. Correct for Elo1, an integral ER membrane elongase; ER membrane (also annotated) is more specific. Supporting Evidence: file:yeast/ELO1/ELO1-uniprot.txt SUBCELLULAR LOCATION: Endoplasmic reticulum membrane |
| GO:0005789 endoplasmic reticulum membrane | EXP PMID:14562095 Global analysis of protein localization in budding yeast. | ACCEPT | Summary: Genome-wide GFP-fusion localization (Huh et al.) is the basis of the UniProt ER membrane location for Elo1. ER membrane is where the elongation cycle (with Ifa38, Phs1, Tsc13) operates. Supporting Evidence: file:yeast/ELO1/ELO1-uniprot.txt SUBCELLULAR LOCATION: Endoplasmic reticulum membrane |
| GO:0005789 endoplasmic reticulum membrane | IBA GO_REF:0000033 | ACCEPT | Summary: PANTHER PTN000125390 ER membrane location for ELO/ELOVL elongases; Elo1 is itself an experimental donor (SGD:S000003732). Correct. Supporting Evidence: file:yeast/ELO1/ELO1-uniprot.txt SUBCELLULAR LOCATION: Endoplasmic reticulum membrane |
| GO:0005789 endoplasmic reticulum membrane | IEA GO_REF:0000044 | ACCEPT | Summary: UniProt SubCell mapping (SL-0097) to ER membrane; matches experimental GFP localization. Supporting Evidence: file:yeast/ELO1/ELO1-uniprot.txt SUBCELLULAR LOCATION: Endoplasmic reticulum membrane |
| GO:0009922 fatty acid elongase activity | EXP PMID:9546663 Fatty acid elongation in yeast--biochemical characteristics ... | ACCEPT | Summary: Dittrich et al. isolated medium-chain elongation-defective mutants, measured malonyl-CoA/NADPH-dependent microsomal elongation activity and identified the affected gene as ELO1; UniProt cites this paper for EC 2.3.1.199. Elo1 is the condensing enzyme of elongase I. Core function. Supporting Evidence: PMID:9546663 In vivo, 12:0 elongation was reduced to 0-10% of the normal level, while 16:0 elongation and VLCFA synthesis were unimpaired. PMID:9546663 identified as the known ELO1 sequence. file:yeast/ELO1/ELO1-uniprot.txt EC=2.3.1.199 |
| GO:0009922 fatty acid elongase activity | IBA GO_REF:0000033 | ACCEPT | Summary: IBA from PANTHER PTN000125390 (ELO/ELOVL condensing enzymes); Elo1 is one of the experimental donors. Elo1 lies well inside the clade, retains the HxxHH catalytic motif-bearing ELO fold, and has direct activity evidence. Core function. Supporting Evidence: file:yeast/ELO1/ELO1-uniprot.txt SIMILARITY: Belongs to the ELO family. PMID:12684876 Elongase I extends C12-C16 fatty acyl-CoAs to C16-C18 fatty acids. |
| GO:0009922 fatty acid elongase activity | IEA GO_REF:0000120 | ACCEPT | Summary: Combined IEA from InterPro IPR002076 (ELO family), RHEA:32727 and EC 2.3.1.199. Correct mapping for this condensing enzyme. Note that the GO definition specifies very-long-chain acyl-CoA substrates (C16+) while Elo1 prefers C12-C16 acyl-CoAs; GO has no separate medium-chain condensing term, so this is the appropriate MF. Supporting Evidence: PMID:12684876 Elongase I extends C12-C16 fatty acyl-CoAs to C16-C18 fatty acids. |
| GO:0009922 fatty acid elongase activity | IMP PMID:12684876 Functional differentiation and selective inactivation of mul... | ACCEPT | Summary: Rossler et al. (abstract-only cache) differentially assayed in vitro elongases and showed that elongase I (C12-C16 primers to C16-C18) is specifically lost in elo1 mutants. Supports Elo1 as the condensing component of elongase I. Supporting Evidence: PMID:12684876 Elongase I extends C12-C16 fatty acyl-CoAs to C16-C18 fatty acids. PMID:12684876 Elongases I, II and III are specifically inactivated in, respectively, elo1, elo2 and elo3 mutants. |
| GO:0016020 membrane | IEA GO_REF:0000002 | TOO GENERAL | Summary: InterPro2GO membrane assignment from the ELO domain; correct but uninformative relative to ER membrane. Supporting Evidence: file:yeast/ELO1/ELO1-uniprot.txt SUBCELLULAR LOCATION: Endoplasmic reticulum membrane |
| GO:0019367 fatty acid elongation, saturated fatty acid | IBA GO_REF:0000033 | ACCEPT | Summary: IBA (PTN000125390) for saturated fatty acid elongation. Directly supported for Elo1: elo1 mutants fail to elongate 12:0-14:0 saturated fatty acids to 16:0-18:0, and elongase I extends C12-C16 acyl-CoAs. Supporting Evidence: PMID:8702485 fails to efficiently elongate (12, 13, or 14) carbon fatty acids. PMID:12684876 Elongase I extends C12-C16 fatty acyl-CoAs to C16-C18 fatty acids. |
| GO:0019368 fatty acid elongation, unsaturated fatty acid | IMP PMID:10850979 Elo1p-dependent carboxy-terminal elongation of C14:1Delta(9)... | ACCEPT | Summary: Schneiter et al. showed that conversion of supplemented C14:1 delta9 to C16:1 delta11 (and C16:1 to C18:1 delta11) is absent in elo1 mutants, and that elo1 ole1 cells cannot grow on C14:1. Elo1 elongates unsaturated as well as saturated medium-chain acyl-CoAs. Supporting Evidence: PMID:10850979 Synthesis of C16:1Delta(11) was dependent on a functional ELO1 gene, indicating that Elo1p catalyzes carboxy-terminal elongation of unsaturated fatty acids |
| GO:0030148 sphingolipid biosynthetic process | IBA GO_REF:0000033 | MARK AS OVER ANNOTATED | Summary: Inherited from PTN000125390 donors including ELO2/ELO3 and ELOVL1, which make the C24-C26 VLCFAs incorporated into ceramide. Elo1 is the medium-chain elongase producing C16-C18 products; the yeast sphingolipid VLCFA requirement is met by Elo2/Elo3 (elo2 elo3 synthetic lethality), with Elo1 providing at most indirect C16-C18 precursors. Reason: Sphingolipid participation is a property of the VLCFA elongases Elo2/Elo3 within the family, not of the C12-C16 elongase Elo1; no Elo1-specific evidence for a sphingolipid role. Propagation Review Root cause: PROPAGATION BAD Failure modes: FUNCTIONAL DIVERGENCE WRONG ORTHOLOG OR PARALOG Sources checked: PANTHER:PTN000125390 SUPPORTS SOURCE BUT NOT TARGET Node donors ELO2/ELO3 (SGD S000004364, S000000630) and ELOVL1 make sphingolipid VLCFAs; the medium-chain Elo1 subfunction does not. Supporting Evidence: PMID:9211877 produce the 26-carbon very long chain fatty acids that are precursors for ceramide and sphingolipids. PMID:12684876 Elongase I extends C12-C16 fatty acyl-CoAs to C16-C18 fatty acids. |
| GO:0034625 fatty acid elongation, monounsaturated fatty acid | IBA GO_REF:0000033 | ACCEPT | Summary: IBA for monounsaturated fatty acid elongation. Directly supported for Elo1, which elongates C14:1 delta9 to C16:1 delta11 and C16:1 to C18:1 delta11 in vivo. Supporting Evidence: PMID:10850979 Synthesis of C16:1Delta(11) was dependent on a functional ELO1 gene, indicating that Elo1p catalyzes carboxy-terminal elongation of unsaturated fatty acids |
| GO:0034626 fatty acid elongation, polyunsaturated fatty acid | IBA GO_REF:0000033 | REMOVE | Summary: IBA for polyunsaturated fatty acid elongation propagated from vertebrate ELOVL2/ELOVL5-type donors. S. cerevisiae has only the delta-9 desaturase Ole1 and synthesizes no PUFAs, and Elo1 substrate studies show monounsaturated (C14:1, C16:1) and saturated substrates only. Reason: Pathway context absent in S. cerevisiae (no endogenous PUFA); donor activity is specific to the vertebrate PUFA elongase subclade. Propagation Review Root cause: PROPAGATION BAD Failure modes: LINEAGE OR TAXON MISMATCH Sources checked: PANTHER:PTN000125390 SUPPORTS SOURCE BUT NOT TARGET Donors are vertebrate PUFA elongases (ELOVL2/4/5-type); S. cerevisiae lacks PUFA substrates. Supporting Evidence: PMID:10850979 Synthesis of C16:1Delta(11) was dependent on a functional ELO1 gene, indicating that Elo1p catalyzes carboxy-terminal elongation of unsaturated fatty acids |
| GO:0042761 very long-chain fatty acid biosynthetic process | IBA GO_REF:0000033 | MARK AS OVER ANNOTATED | Summary: IBA from PTN000125390 donors (ELO2/ELO3, ELOVL1/3/4/7). GO defines VLCFA as >C22, whereas Elo1 extends C12-C16 acyl-CoAs to C16-C18; VLCFA synthesis is unimpaired in elo1 mutants. Within yeast, VLCFA synthesis is the job of Elo2/Elo3. Reason: Product chain length of Elo1 (C16-C18) is outside the VLCFA definition; experimental data show VLCFA synthesis is Elo1-independent. Propagation Review Root cause: PROPAGATION BAD Failure modes: FUNCTIONAL DIVERGENCE GRANULARITY MISMATCH Sources checked: PANTHER:PTN000125390 SUPPORTS SOURCE BUT NOT TARGET VLCFA donors are ELO2/ELO3 and ELOVL1/3/4/7; Elo1 produces C16-C18 only. Supporting Evidence: PMID:9546663 In vivo, 12:0 elongation was reduced to 0-10% of the normal level, while 16:0 elongation and VLCFA synthesis were unimpaired. PMID:12684876 Elongase I extends C12-C16 fatty acyl-CoAs to C16-C18 fatty acids. |
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Download this section (compressed HTML)Q: Does Elo1 contribute measurably to C16-C18 acyl-CoA supply under normal (FAS-active) growth, or only when cells import medium-chain fatty acids?
Q: Is the 3-ketoacyl-CoA reductase Ifa38 (or Ayr1) the partner of Elo1 in elongase I, given that Rossler et al. found Ybr159w shared by elongases II and III?
Experiment: Express Elo1 and Elo1/Elo2 chimeras in elo1 elo2 elo3 (rescued) backgrounds and measure in vitro condensation with C10-C20 acyl-CoA primers by LC-MS.
Hypothesis: Elo1 specificity for C12-C14 acyl-CoA is intrinsic to its acyl-binding tunnel (molecular caliper).
Elongase I, medium-chain acyl elongase; catalyzes carboxy-terminal elongation of unsaturated C12-C16 fatty acyl-CoAs to C16-C18 fatty acids; ELO1 has a paralog, ELO2, that arose from the whole genome duplication
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