Natural Substrates | Organism | Comment (Nat. Sub.) | Natural Products | Comment (Nat. Pro.) | Rev. | Reac. |
---|---|---|---|---|---|---|
2-methylpropanoyl-CoA | Cupriavidus metallidurans | - |
butanoyl-CoA | - |
r | |
2-methylpropanoyl-CoA | Cupriavidus metallidurans ATCC 43123 | - |
butanoyl-CoA | - |
r |
Organism | UniProt | Comment | Textmining |
---|---|---|---|
Cupriavidus metallidurans | Q1LRY0 | - |
- |
Cupriavidus metallidurans ATCC 43123 | Q1LRY0 | - |
- |
Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
---|---|---|---|---|---|---|
2-methylpropanoyl-CoA | - |
Cupriavidus metallidurans | butanoyl-CoA | - |
r | |
2-methylpropanoyl-CoA | - |
Cupriavidus metallidurans ATCC 43123 | butanoyl-CoA | - |
r |
Synonyms | Comment | Organism |
---|---|---|
IcmF | - |
Cupriavidus metallidurans |
Cofactor | Comment | Organism | Structure |
---|---|---|---|
5'-deoxyadenosylcobalamin | AdoCbl, required, affinity for AdoCbl is unaffected by the presence of GDP | Cupriavidus metallidurans | |
additional information | the GTPase activity of IcmF powers the ejection of the inactive cob(II)alamin cofactor and requires the presence of an acceptor protein, adenosyltransferase, for receiving it. Adenosyltransferase in turn converts cob(II)alamin to AdoCbl in the presence of ATP and a reductant. The repaired cofactor is then reloaded onto IcmF in a GTPase-gated step. Transfer of inactive cob(II)alamin from ATR to IcmF is disfavored. The mechanistic details of cofactor loading and offloading from the AdoCbl-dependent IcmF are distinct from those of the homologous methylmalonyl-CoA mutase/G-protein chaperone system. The nonhydrolyzable analogue, GMPPCP, weakens the affinity of IcmF for AdoCbl by about 60fold and allows loading of only one of two cofactor-binding sites. AdoCbl binding in the presence of GMPPCP is primarily enthalpically driven. The slight inhibition of AdoCbl transfer in the presence of GTP or GDP is likely due to the higher affinity of ATR for AdoCbl in the presence of these nucleotides, while ATP enhances the transfer. kinetics, overview | Cupriavidus metallidurans |
General Information | Comment | Organism |
---|---|---|
additional information | GDP binding by the enzyme is accompanied by favorable enthalpic and entropic changes and is unaffected by 5'-deoxyadenosylcobalamin | Cupriavidus metallidurans |
physiological function | IcmF is a 5'-deoxyadenosylcobalamin (AdoCbl)-dependent enzyme that catalyzes the carbon skeleton rearrangement of isobutyryl-CoA to butyryl-CoA. It is a bifunctional protein resulting from the fusion of a G-protein chaperone with GTPase activity and the cofactor- and substrate-binding mutase domains with isomerase activity. IcmF is prone to inactivation during catalytic turnover, thus setting up its dependence on a cofactor repair system. The GTPase activity of IcmF powers the ejection of the inactive cob(II)alamin cofactor and requires the presence of an acceptor protein, adenosyltransferase, for receiving it. Adenosyltransferase in turn converts cob(II)alamin to AdoCbl in the presence of ATP and a reductant. The repaired cofactor is then reloaded onto IcmF in a GTPase-gated step. The mechanistic details of cofactor loading and offloading from the AdoCbl-dependent IcmF are distinct from those of the homologous methylmalonyl-CoA mutase/G-protein chaperone system, overview | Cupriavidus metallidurans |