moaA encodes the canonical radical-SAM GTP 3',8'-cyclase of Pseudomonas putida KT2440. It binds two [4Fe-4S] clusters and converts GTP to the cyclic intermediate that MoaC rearranges to cyclic pyranopterin monophosphate during the first stage of molybdenum-cofactor biosynthesis.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0003824 catalytic activity | IEA GO_REF:0000002 | MODIFY | Summary: The generic catalytic-activity term should be replaced by the exact MoaA reaction. Reason: Reviewed UniProt/HAMAP assigns EC 4.1.99.22 GTP 3',8'-cyclase activity to Q88E69. Proposed replacements: GTP 3',8'-cyclase activity Supporting Evidence: file:PSEPK/moaA/moaA-uniprot.txt DE RecName: Full=GTP 3',8-cyclase {ECO:0000255|HAMAP-Rule:MF_01225}; DE EC=4.1.99.22 {ECO:0000255|HAMAP-Rule:MF_01225}; |
| GO:0005525 GTP binding | IEA GO_REF:0000104 | KEEP AS NON CORE | Summary: GTP binding is a valid substrate-binding property but is less informative than the catalytic term. Reason: GTP is the substrate in the reviewed UniProt reaction for Q88E69. |
| GO:0006777 Mo-molybdopterin cofactor biosynthetic process | IEA GO_REF:0000120 | ACCEPT | Summary: MoaA performs the first committed reaction of Mo-molybdopterin cofactor biosynthesis. Reason: UniProt places the GTP cyclization reaction in molybdopterin biosynthesis. |
| GO:0046872 metal ion binding | IEA GO_REF:0000002 | KEEP AS NON CORE | Summary: Generic metal-ion binding is compatible with the two iron-sulfur clusters but is non-core. Reason: The more informative retained annotations specify iron-sulfur and [4Fe-4S] cluster binding. |
| GO:0051536 iron-sulfur cluster binding | IEA GO_REF:0000002 | MARK AS OVER ANNOTATED | Summary: This broad iron-sulfur-cluster binding term is redundant with the more specific retained [4Fe-4S]-cluster binding annotation. Reason: Reviewed UniProt specifies [4Fe-4S] clusters, so GO:0051539 captures the supported cofactor binding more precisely. |
| GO:0051539 4 iron, 4 sulfur cluster binding | IEA GO_REF:0000120 | KEEP AS NON CORE | Summary: The specific [4Fe-4S]-cluster binding annotation is supported but is not the catalytic function. Reason: Reviewed UniProt explicitly assigns two [4Fe-4S] clusters to Q88E69. |
| GO:0061798 GTP 3',8'-cyclase activity | IEA GO_REF:0000120 | ACCEPT | Summary: GTP 3',8'-cyclase activity is the exact core molecular function of canonical KT2440 MoaA. Reason: The reviewed entry supplies the exact reaction, Rhea:49576, and EC 4.1.99.22. Supporting Evidence: file:PSEPK/moaA/moaA-uniprot.txt CC -!- CATALYTIC ACTIVITY: CC Reaction=GTP + AH2 + S-adenosyl-L-methionine = (8S)-3',8-cyclo-7,8- CC dihydroguanosine 5'-triphosphate + 5'-deoxyadenosine + L-methionine + CC A + H(+); Xref=Rhea:RHEA:49576, ChEBI:CHEBI:13193, ChEBI:CHEBI:15378, CC ChEBI:CHEBI:17319, ChEBI:CHEBI:17499, ChEBI:CHEBI:37565, CC ChEBI:CHEBI:57844, ChEBI:CHEBI:59789, ChEBI:CHEBI:131766; CC EC=4.1.99.22; Evidence={ECO:0000255|HAMAP-Rule:MF_01225}; file:PSEPK/moaA/moaA-deep-research-openscientist.md MoaA is a **radical S-adenosyl-L-methionine (SAM) metalloenzyme, GTP 3',8-cyclase**, that catalyzes the **first and committed step of molybdenum cofactor (Moco) biosynthesis**. |
| GO:0061799 cyclic pyranopterin monophosphate synthase activity | IEA GO_REF:0000118 | REMOVE | Summary: Cyclic pyranopterin monophosphate synthase activity belongs to MoaC, not MoaA. Reason: MoaA makes the cyclic GTP intermediate; the distinct MoaC enzyme converts that intermediate to cPMP. Supporting Evidence: file:PSEPK/moaA/moaA-uniprot.txt DE RecName: Full=GTP 3',8-cyclase {ECO:0000255|HAMAP-Rule:MF_01225}; file:PSEPK/moaC/moaC-uniprot.txt DE RecName: Full=Cyclic pyranopterin monophosphate synthase {ECO:0000255|HAMAP-Rule:MF_01224}; file:PSEPK/moaA/moaA-deep-research-openscientist.md MoaA is **not** the enzyme that forms the cyclic phosphate or releases pyrophosphate (that is MoaC) |
| GO:1904047 S-adenosyl-L-methionine binding | IEA GO_REF:0000104 | KEEP AS NON CORE | Summary: SAM binding is a valid radical-SAM mechanistic property but is not the core catalytic annotation. Reason: S-adenosyl-L-methionine is a reactant coordinated by one of the two [4Fe-4S] clusters. |
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Experiment: Measure cPMP production and molybdoenzyme activity in single and combined moaA-family deletion strains, with complementation by each paralog.
Type: targeted genetics and metabolite profiling
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