4XC8 image
Entry Detail
PDB ID:
4XC8
Keywords:
Title:
Isobutyryl-CoA mutase fused with bound butyryl-CoA, GDP, and Mg and without cobalamin (apo-IcmF/GDP)
Biological Source:
PDB Version:
Deposition Date:
2014-12-17
Release Date:
2015-02-11
Method Details:
Experimental Method:
Resolution:
3.25 Å
R-Value Free:
0.22
R-Value Work:
0.20
R-Value Observed:
0.20
Space Group:
H 3 2
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:Isobutyryl-CoA mutase fused
Chain IDs:A, B
Chain Length:1113
Number of Molecules:2
Biological Source:Ralstonia metallidurans (strain CH34 / ATCC 43123 / DSM 2839)
Primary Citation
Visualization of a radical B12 enzyme with its G-protein chaperone.
Proc.Natl.Acad.Sci.USA 112 2419 2424 (2015)
PMID: 25675500 DOI: 10.1073/pnas.1419582112

Abstact

G-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.

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