Cem1 is a mitochondrial beta-ketoacyl-ACP synthase of the dissociated type II fatty-acid synthesis machinery. Its conserved ketoacyl-synthase domains and catalytic residues support malonyl-ACP-dependent two-carbon acyl-chain extension. Transfer from characterized mitochondrial OXSM/Cem1 homologs supports a role in producing acyl-ACP intermediates needed for mitochondrial metabolism, while its exact substrate range in fission yeast remains unresolved.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0004315 3-oxoacyl-[acyl-carrier-protein] synthase activity | IBA GO_REF:0000033 | ACCEPT | Summary: 3-oxoacyl-[acyl-carrier-protein] synthase activity is supported. Reason: The beta-ketoacyl-synthase N- and C-terminal domains and annotated catalytic Cys/His residues establish the relevant enzyme family. Human mitochondrial OXSM directly elongates acyl-ACP and complements budding-yeast cem1 deficiency (PMID:15668256); this supports conserved mitochondrial fatty-acid synthesis by inference, without transferring an exact substrate preference to fission yeast. Supporting Evidence: file:SCHPO/cem1/cem1-uniprot.txt DR InterPro; IPR000794; Beta-ketoacyl_synthase. PMID:15668256 The enzyme can elongate acyl-chains containing 2-14 carbon atoms with malonyl moieties attached in thioester linkage to the human mitochondrial acyl carrier protein and is able to restore growth to the respiratory-deficient yeast mutant cem1 that lacks the endogenous mitochondrial beta-ketoacyl synthase and exhibits lowered lipoic acid levels. |
| GO:0004315 3-oxoacyl-[acyl-carrier-protein] synthase activity | IEA GO_REF:0000120 | ACCEPT | Summary: 3-oxoacyl-[acyl-carrier-protein] synthase activity is supported. Reason: The beta-ketoacyl-synthase N- and C-terminal domains and annotated catalytic Cys/His residues establish the relevant enzyme family. Human mitochondrial OXSM directly elongates acyl-ACP and complements budding-yeast cem1 deficiency (PMID:15668256); this supports conserved mitochondrial fatty-acid synthesis by inference, without transferring an exact substrate preference to fission yeast. Supporting Evidence: file:SCHPO/cem1/cem1-uniprot.txt DR InterPro; IPR000794; Beta-ketoacyl_synthase. PMID:15668256 The enzyme can elongate acyl-chains containing 2-14 carbon atoms with malonyl moieties attached in thioester linkage to the human mitochondrial acyl carrier protein and is able to restore growth to the respiratory-deficient yeast mutant cem1 that lacks the endogenous mitochondrial beta-ketoacyl synthase and exhibits lowered lipoic acid levels. |
| GO:0004315 3-oxoacyl-[acyl-carrier-protein] synthase activity | ISS GO_REF:0000024 | ACCEPT | Summary: 3-oxoacyl-[acyl-carrier-protein] synthase activity is supported. Reason: The beta-ketoacyl-synthase N- and C-terminal domains and annotated catalytic Cys/His residues establish the relevant enzyme family. Human mitochondrial OXSM directly elongates acyl-ACP and complements budding-yeast cem1 deficiency (PMID:15668256); this supports conserved mitochondrial fatty-acid synthesis by inference, without transferring an exact substrate preference to fission yeast. Supporting Evidence: file:SCHPO/cem1/cem1-uniprot.txt DR InterPro; IPR000794; Beta-ketoacyl_synthase. PMID:15668256 The enzyme can elongate acyl-chains containing 2-14 carbon atoms with malonyl moieties attached in thioester linkage to the human mitochondrial acyl carrier protein and is able to restore growth to the respiratory-deficient yeast mutant cem1 that lacks the endogenous mitochondrial beta-ketoacyl synthase and exhibits lowered lipoic acid levels. |
| GO:0005739 mitochondrion | HDA PMID:16823372 ORFeome cloning and global analysis of protein localization ... | ACCEPT | Summary: mitochondrion is supported. Reason: The PomBase HDA annotation records mitochondrial localization in PMID:16823372, concordant with the mitochondrial OXSM/Cem1 family assignment and N-terminal targeting sequence. Retain this localization, distinguishing curated individual-screen evidence from the general screen abstract. The source excerpt records the target HDA/IC annotation, not a reinspection of the individual microscopy image. Supporting Evidence: file:SCHPO/cem1/cem1-uniprot.txt DR GO; GO:0005739; C:mitochondrion; HDA:PomBase. |
| GO:0005739 mitochondrion | IBA GO_REF:0000033 | ACCEPT | Summary: mitochondrion is supported. Reason: The PomBase HDA annotation records mitochondrial localization in PMID:16823372, concordant with the mitochondrial OXSM/Cem1 family assignment and N-terminal targeting sequence. Retain this localization, distinguishing curated individual-screen evidence from the general screen abstract. Supporting Evidence: file:SCHPO/cem1/cem1-uniprot.txt DR GO; GO:0005739; C:mitochondrion; HDA:PomBase. |
| GO:0005739 mitochondrion | IEA GO_REF:0000044 | ACCEPT | Summary: mitochondrion is supported. Reason: The PomBase HDA annotation records mitochondrial localization in PMID:16823372, concordant with the mitochondrial OXSM/Cem1 family assignment and N-terminal targeting sequence. Retain this localization, distinguishing curated individual-screen evidence from the general screen abstract. Supporting Evidence: file:SCHPO/cem1/cem1-uniprot.txt DR GO; GO:0005739; C:mitochondrion; HDA:PomBase. |
| GO:0006633 fatty acid biosynthetic process | IBA GO_REF:0000033 | ACCEPT | Summary: fatty acid biosynthetic process is supported. Reason: The beta-ketoacyl-synthase N- and C-terminal domains and annotated catalytic Cys/His residues establish the relevant enzyme family. Human mitochondrial OXSM directly elongates acyl-ACP and complements budding-yeast cem1 deficiency (PMID:15668256); this supports conserved mitochondrial fatty-acid synthesis by inference, without transferring an exact substrate preference to fission yeast. Supporting Evidence: file:SCHPO/cem1/cem1-uniprot.txt DR InterPro; IPR000794; Beta-ketoacyl_synthase. PMID:15668256 The enzyme can elongate acyl-chains containing 2-14 carbon atoms with malonyl moieties attached in thioester linkage to the human mitochondrial acyl carrier protein and is able to restore growth to the respiratory-deficient yeast mutant cem1 that lacks the endogenous mitochondrial beta-ketoacyl synthase and exhibits lowered lipoic acid levels. |
| GO:0006633 fatty acid biosynthetic process | IEA GO_REF:0000120 | ACCEPT | Summary: fatty acid biosynthetic process is supported. Reason: The beta-ketoacyl-synthase N- and C-terminal domains and annotated catalytic Cys/His residues establish the relevant enzyme family. Human mitochondrial OXSM directly elongates acyl-ACP and complements budding-yeast cem1 deficiency (PMID:15668256); this supports conserved mitochondrial fatty-acid synthesis by inference, without transferring an exact substrate preference to fission yeast. Supporting Evidence: file:SCHPO/cem1/cem1-uniprot.txt DR InterPro; IPR000794; Beta-ketoacyl_synthase. PMID:15668256 The enzyme can elongate acyl-chains containing 2-14 carbon atoms with malonyl moieties attached in thioester linkage to the human mitochondrial acyl carrier protein and is able to restore growth to the respiratory-deficient yeast mutant cem1 that lacks the endogenous mitochondrial beta-ketoacyl synthase and exhibits lowered lipoic acid levels. |
| GO:0016746 acyltransferase activity | IEA GO_REF:0000002 | MODIFY | Summary: acyltransferase activity is reviewed in the context of cem1. Reason: The broad acyltransferase activity annotation is compatible with the biology, but 3-oxoacyl-[acyl-carrier-protein] synthase activity captures the supported cem1 function more precisely. Proposed replacements: 3-oxoacyl-[acyl-carrier-protein] synthase activity Supporting Evidence: file:SCHPO/cem1/cem1-uniprot.txt DR InterPro; IPR000794; Beta-ketoacyl_synthase. PMID:15668256 The enzyme can elongate acyl-chains containing 2-14 carbon atoms with malonyl moieties attached in thioester linkage to the human mitochondrial acyl carrier protein and is able to restore growth to the respiratory-deficient yeast mutant cem1 that lacks the endogenous mitochondrial beta-ketoacyl synthase and exhibits lowered lipoic acid levels. |
| GO:0016747 acyltransferase activity, transferring groups other than amino-acyl groups | IEA GO_REF:0000002 | MODIFY | Summary: acyltransferase activity, transferring groups other than amino-acyl groups is reviewed in the context of cem1. Reason: The broad acyltransferase activity, transferring groups other than amino-acyl groups annotation is compatible with the biology, but 3-oxoacyl-[acyl-carrier-protein] synthase activity captures the supported cem1 function more precisely. Proposed replacements: 3-oxoacyl-[acyl-carrier-protein] synthase activity Supporting Evidence: file:SCHPO/cem1/cem1-uniprot.txt DR InterPro; IPR000794; Beta-ketoacyl_synthase. PMID:15668256 The enzyme can elongate acyl-chains containing 2-14 carbon atoms with malonyl moieties attached in thioester linkage to the human mitochondrial acyl carrier protein and is able to restore growth to the respiratory-deficient yeast mutant cem1 that lacks the endogenous mitochondrial beta-ketoacyl synthase and exhibits lowered lipoic acid levels. |
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