4xc7
From Proteopedia
Isobutyryl-CoA mutase fused with bound butyryl-CoA and without cobalamin or GDP (apo-IcmF)
Structural highlights
FunctionICMF_CUPMC Catalyzes the reversible interconversion of isobutyryl-CoA and n-butyryl-CoA, and to a much lesser extent, of pivalyl-CoA and isovaleryl-CoA, using radical chemistry (PubMed:22167181). Also exhibits GTPase activity, associated with its G-protein domain (MeaI) that functions as a chaperone that assists cofactor delivery and proper holo-enzyme assembly (PubMed:22167181, PubMed:25675500). The G-domain of IcmF has also a role in its cofactor repair (PubMed:28130442). Does not display ATPase activity.[1] [2] [3] Publication Abstract from PubMedG-protein metallochaperones ensure fidelity during cofactor assembly for a variety of metalloproteins, including adenosylcobalamin (AdoCbl)-dependent methylmalonyl-CoA mutase and hydrogenase, and thus have both medical and biofuel development applications. Here, we present crystal structures of IcmF, a natural fusion protein of AdoCbl-dependent isobutyryl-CoA mutase and its corresponding G-protein chaperone, which reveal the molecular architecture of a G-protein metallochaperone in complex with its target protein. These structures show that conserved G-protein elements become ordered upon target protein association, creating the molecular pathways that both sense and report on the cofactor loading state. Structures determined of both apo- and holo-forms of IcmF depict both open and closed enzyme states, in which the cofactor-binding domain is alternatively positioned for cofactor loading and for catalysis. Notably, the G protein moves as a unit with the cofactor-binding domain, providing a visualization of how a chaperone assists in the sequestering of a precious cofactor inside an enzyme active site. Visualization of a radical B12 enzyme with its G-protein chaperone.,Jost M, Cracan V, Hubbard PA, Banerjee R, Drennan CL Proc Natl Acad Sci U S A. 2015 Feb 24;112(8):2419-24. doi:, 10.1073/pnas.1419582112. Epub 2015 Feb 9. PMID:25675500[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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