8STA

Isobutyryl-CoA mutase fused in the presence of GMPPCP

8STA の概要

• エントリーDOI: 10.2210/pdb8sta/pdb
• 関連するPDBエントリー: 8SSL
• EMDBエントリー: 40758
• 分子名称: Isobutyryl-CoA mutase fused (1 entity in total)
• 機能のキーワード: supramolecular complex, b12-binding, g-protein chaperone, mutase, isomerase
• 由来する生物種: Cupriavidus metallidurans CH34
• タンパク質・核酸の鎖数: 4
• 化学式量合計: 491710.34

構造登録者

Vaccaro, F.A.,Drennan, C.L. (登録日: 2023-05-09, 公開日: 2023-08-09, 最終更新日: 2023-09-13)

主引用文献

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

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: 37517695
DOI: 10.1016/j.jbc.2023.105109

実験手法

ELECTRON MICROSCOPY (7.3 Å)