mobA encodes the cytoplasmic molybdenum-cofactor guanylyltransferase that transfers GMP from GTP to Mo-molybdopterin, producing the MGD cofactor variant used by a subset of molybdoenzymes. This is an optional nucleotide-maturation branch downstream of conserved Mo-MPT formation.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0003824 catalytic activity | IEA GO_REF:0000002 | MODIFY | Summary: Generic catalytic activity should be replaced by the exact MobA reaction. Reason: Reviewed UniProt/HAMAP assigns EC 2.7.7.77 Mo-MPT guanylyltransferase activity. Proposed replacements: molybdenum cofactor guanylyltransferase activity Supporting Evidence: file:PSEPK/mobA/mobA-uniprot.txt CC -!- FUNCTION: Transfers a GMP moiety from GTP to Mo-molybdopterin (Mo-MPT) CC cofactor (Moco or molybdenum cofactor) to form Mo-molybdopterin guanine CC dinucleotide (Mo-MGD) cofactor. {ECO:0000255|HAMAP-Rule:MF_00316}. |
| GO:0005525 GTP binding | IEA GO_REF:0000104 | KEEP AS NON CORE | Summary: GTP binding is valid substrate binding but less informative than the catalytic term. Reason: GTP donates GMP in the reviewed MobA reaction. |
| GO:0005737 cytoplasm | IEA GO_REF:0000120 | KEEP AS NON CORE | Summary: Cytoplasmic localization is appropriate for this soluble cofactor-maturation enzyme. Reason: Q88HA3 lacks membrane/export features and acts on soluble Mo-MPT. |
| GO:0006777 Mo-molybdopterin cofactor biosynthetic process | IEA GO_REF:0000002 | ACCEPT | Summary: MobA participates in the optional nucleotide-maturation branch of Mo-molybdopterin cofactor biosynthesis. Reason: The exact MobA reaction produces the Mo-MGD cofactor variant, so this broad biosynthetic-process term is accurate without asserting downstream bis-MGD assembly. Supporting Evidence: file:PSEPK/mobA/mobA-uniprot.txt CC -!- FUNCTION: Transfers a GMP moiety from GTP to Mo-molybdopterin (Mo-MPT) CC cofactor (Moco or molybdenum cofactor) to form Mo-molybdopterin guanine CC dinucleotide (Mo-MGD) cofactor. {ECO:0000255|HAMAP-Rule:MF_00316}. |
| GO:0016779 nucleotidyltransferase activity | IEA GO_REF:0000120 | MODIFY | Summary: The generic nucleotidyltransferase term should be replaced by the exact MobA activity. Reason: UniProt specifies GMP transfer from GTP to Mo-MPT. Proposed replacements: molybdenum cofactor guanylyltransferase activity Supporting Evidence: file:PSEPK/mobA/mobA-uniprot.txt CC -!- CATALYTIC ACTIVITY: CC Reaction=Mo-molybdopterin + GTP + H(+) = Mo-molybdopterin guanine CC dinucleotide + diphosphate; Xref=Rhea:RHEA:34243, ChEBI:CHEBI:15378, CC ChEBI:CHEBI:33019, ChEBI:CHEBI:37565, ChEBI:CHEBI:71302, CC ChEBI:CHEBI:71310; EC=2.7.7.77; Evidence={ECO:0000255|HAMAP- CC Rule:MF_00316}; |
| GO:0019720 Mo-molybdopterin cofactor metabolic process | IEA GO_REF:0000104 | MARK AS OVER ANNOTATED | Summary: This broad metabolic-process parent is less precise than the retained Mo-molybdopterin cofactor biosynthetic-process annotation. Reason: GO:0006777 more specifically captures the biosynthetic context of MobA-catalyzed Mo-MGD formation. Supporting Evidence: file:PSEPK/mobA/mobA-uniprot.txt CC -!- FUNCTION: Transfers a GMP moiety from GTP to Mo-molybdopterin (Mo-MPT) CC cofactor (Moco or molybdenum cofactor) to form Mo-molybdopterin guanine CC dinucleotide (Mo-MGD) cofactor. {ECO:0000255|HAMAP-Rule:MF_00316}. |
| GO:0061603 molybdenum cofactor guanylyltransferase activity | IEA GO_REF:0000120 | ACCEPT | Summary: This is the exact core molecular function of MobA. Reason: The reviewed entry provides Rhea:34243 and EC 2.7.7.77 for Mo-MPT guanylylation. Supporting Evidence: file:PSEPK/mobA/mobA-uniprot.txt CC -!- CATALYTIC ACTIVITY: CC Reaction=Mo-molybdopterin + GTP + H(+) = Mo-molybdopterin guanine CC dinucleotide + diphosphate; Xref=Rhea:RHEA:34243, ChEBI:CHEBI:15378, CC ChEBI:CHEBI:33019, ChEBI:CHEBI:37565, ChEBI:CHEBI:71302, CC ChEBI:CHEBI:71310; EC=2.7.7.77; Evidence={ECO:0000255|HAMAP- CC Rule:MF_00316}; file:PSEPK/mobA/mobA-deep-research-openscientist.md GTP + Mo-MPT --(MobA, Mg2+)--> MGD + PPi |
| GO:0070568 guanylyltransferase activity | IEA GO_REF:0000104 | MODIFY | Summary: The broad guanylyltransferase term should be replaced by the Mo-cofactor-specific child term. Reason: The acceptor is specifically Mo-molybdopterin. Proposed replacements: molybdenum cofactor guanylyltransferase activity Supporting Evidence: file:PSEPK/mobA/mobA-uniprot.txt CC -!- FUNCTION: Transfers a GMP moiety from GTP to Mo-molybdopterin (Mo-MPT) CC cofactor (Moco or molybdenum cofactor) to form Mo-molybdopterin guanine CC dinucleotide (Mo-MGD) cofactor. {ECO:0000255|HAMAP-Rule:MF_00316}. |
| GO:1902758 bis(molybdopterin guanine dinucleotide)molybdenum biosynthetic process | IEA GO_REF:0000118 | MARK AS OVER ANNOTATED | Summary: The bis-MGD-specific process extends beyond the one-MGD product of the MobA reaction. Reason: Reviewed target UniProt supports Mo-MGD formation but does not establish downstream bis-MGD assembly by MobA. Supporting Evidence: file:PSEPK/mobA/mobA-uniprot.txt CC -!- CATALYTIC ACTIVITY: CC Reaction=Mo-molybdopterin + GTP + H(+) = Mo-molybdopterin guanine CC dinucleotide + diphosphate; Xref=Rhea:RHEA:34243, ChEBI:CHEBI:15378, CC ChEBI:CHEBI:33019, ChEBI:CHEBI:37565, ChEBI:CHEBI:71302, CC ChEBI:CHEBI:71310; EC=2.7.7.77; Evidence={ECO:0000255|HAMAP- CC Rule:MF_00316}; |
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Download this section (compressed HTML)Experiment: Quantify Mo-MGD formation by purified Q88HA3 and test complementation of an MGD-dependent molybdoenzyme phenotype in a mobA deletion strain.
Type: enzyme assay and genetic complementation
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