8SSL
Isobutyryl-CoA mutase fused Q341A in the presence of GTP
Summary for 8SSL
| Entry DOI | 10.2210/pdb8ssl/pdb |
| EMDB information | 40751 |
| Descriptor | Fused isobutyryl-CoA mutase, GUANOSINE-5'-DIPHOSPHATE, MAGNESIUM ION (3 entities in total) |
| Functional Keywords | supramolecular complex, b12-binding, g-protein chaperone, isomerase |
| Biological source | Cupriavidus metallidurans CH34 |
| Total number of polymer chains | 3 |
| Total formula weight | 369965.48 |
| Authors | |
| Primary citation | Vaccaro, F.A.,Faber, D.A.,Andree, G.A.,Born, D.A.,Kang, G.,Fonseca, D.R.,Jost, M.,Drennan, C.L. Structural insight into G-protein chaperone-mediated maturation of a bacterial adenosylcobalamin-dependent mutase. J.Biol.Chem., 299:105109-105109, 2023 Cited by PubMed Abstract: G-protein metallochaperones are essential for the proper maturation of numerous metalloenzymes. The G-protein chaperone MMAA in humans (MeaB in bacteria) uses GTP hydrolysis to facilitate the delivery of adenosylcobalamin (AdoCbl) to AdoCbl-dependent methylmalonyl-CoA mutase, an essential metabolic enzyme. This G-protein chaperone also facilitates the removal of damaged cobalamin (Cbl) for repair. Although most chaperones are standalone proteins, isobutyryl-CoA mutase fused (IcmF) has a G-protein domain covalently attached to its target mutase. We previously showed that dimeric MeaB undergoes a 180° rotation to reach a state capable of GTP hydrolysis (an active G-protein state), in which so-called switch III residues of one protomer contact the G-nucleotide of the other protomer. However, it was unclear whether other G-protein chaperones also adopted this conformation. Here, we show that the G-protein domain in a fused system forms a similar active conformation, requiring IcmF oligomerization. IcmF oligomerizes both upon Cbl damage and in the presence of the nonhydrolyzable GTP analog, guanosine-5'-[(β,γ)-methyleno]triphosphate, forming supramolecular complexes observable by mass photometry and EM. Cryo-EM structural analysis reveals that the second protomer of the G-protein intermolecular dimer props open the mutase active site using residues of switch III as a wedge, allowing for AdoCbl insertion or damaged Cbl removal. With the series of structural snapshots now available, we now describe here the molecular basis of G-protein-assisted AdoCbl-dependent mutase maturation, explaining how GTP binding prepares a mutase for cofactor delivery and how GTP hydrolysis allows the mutase to capture the cofactor. PubMed: 37517695DOI: 10.1016/j.jbc.2023.105109 PDB entries with the same primary citation |
| Experimental method | ELECTRON MICROSCOPY (4.6 Å) |
Structure validation
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