moaC (PP_1292) of Pseudomonas putida KT2440 encodes cyclic pyranopterin monophosphate (cPMP) synthase, the second enzyme of molybdenum cofactor biosynthesis. By orthology with the characterised Escherichia coli MoaC, it rearranges (8S)-3',8-cyclo-7,8-dihydroguanosine 5'-triphosphate, the product of the radical SAM GTP 3',8-cyclase MoaA, into cPMP (precursor Z) and diphosphate. cPMP is then converted to molybdopterin by the MoaD-MoaE molybdopterin synthase encoded beside moaC. The 156-residue protein carries the MoaC family fold and the conserved active-site aspartate; the E. coli enzyme is a cytoplasmic homohexamer with active sites at the dimer interfaces.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0006777 Mo-molybdopterin cofactor biosynthetic process | IEA GO_REF:0000120 | ACCEPT | Summary: MoaC catalyses the cPMP-forming step of Moco biosynthesis. Reason: Q88NC0 is a HAMAP MoaC family member (MF_01224, TIGR00581, PANTHER PTHR22960:SF29). The characterised E. coli ortholog performs the pyranopterin-forming step of the pathway (PMID:25941396), so the protein does work in the process. Same action as genes/ECOLI/moaC. Supporting Evidence: file:PSEPK/moaC/moaC-uniprot.txt SIMILARITY: Belongs to the MoaC family. PMID:25941396 During Moco biosynthesis, the characteristic pyranopterin ring is constructed by a complex rearrangement of guanosine 5'-triphosphate (GTP) into cyclic pyranopterin (cPMP) through the action of two enzymes, MoaA and MoaC |
| GO:0061799 cyclic pyranopterin monophosphate synthase activity | IEA GO_REF:0000120 | ACCEPT | Summary: Cyclic pyranopterin monophosphate synthase activity is the correct core molecular function for MoaC. Reason: HAMAP rule MF_01224 assigns the cPMP synthase reaction (RHEA:49580). The HAMAP substrate-binding and active-site positions are present in Q88NC0, and the reaction is experimentally established for the E. coli ortholog P0A738 (PMID:25941396). KT2440 MoaC has not been assayed, so this is a family-level inference; same action as genes/ECOLI/moaC. Supporting Evidence: file:PSEPK/moaC/moaC-uniprot.txt FUNCTION: Catalyzes the conversion of (8S)-3',8-cyclo-7,8- dihydroguanosine 5'-triphosphate to cyclic pyranopterin monophosphate (cPMP). PMID:25941396 These observations provided strong evidence that the physiological function of MoaA is the conversion of GTP to 3',8-cH2GTP (GTP 3',8-cyclase), and that of MoaC is to catalyze the rearrangement of 3',8-cH2GTP into cPMP (cPMP synthase). file:PSEPK/moaC/moaC-deep-research-falcon.md MoaC catalyzes the conversion of the MoaA product, 3′,8-cH2GTP, into cyclic pyranopterin monophosphate (cPMP). |
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Download this section (compressed HTML)Q: Does KT2440 MoaC function independently as a homohexamer in vivo or require stable association with upstream MoaA pathway components?
Experiment: Assay cPMP production with purified MoaC and pathway precursor, and compare molybdoenzyme activity in wild-type and moaC knockout strains.
Type: enzyme assay and molybdoenzyme activity profiling
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