%0 Journal Article
%T The cryo-EM structure of trypanosome 3-methylcrotonyl-CoA carboxylase provides mechanistic and dynamic insights into its enzymatic function.
%A Plaza-Pegueroles A
%A Aphasizheva I
%A Aphasizhev R
%A Fernández-Tornero C
%A Ruiz FM
%J Structure
%V 32
%N 7
%D 2024 Jul 11
%M 38593794
%F 5.871
%R 10.1016/j.str.2024.03.010
%X 3-Methylcrotonyl-CoA carboxylase (MCC) catalyzes the two-step, biotin-dependent production of 3-methylglutaconyl-CoA, an essential intermediate in leucine catabolism. Given the critical metabolic role of MCC, deficiencies in this enzyme lead to organic aciduria, while its overexpression is linked to tumor development. MCC is a dodecameric enzyme composed of six copies of each α- and β-subunit. We present the cryo-EM structure of the endogenous MCC holoenzyme from Trypanosoma brucei in a non-filamentous state at 2.4 Å resolution. Biotin is covalently bound to the biotin carboxyl carrier protein domain of α-subunits and positioned in a non-canonical pocket near the active site of neighboring β-subunit dimers. Moreover, flexibility of key residues at α-subunit interfaces and loops enables pivoting of α-subunit trimers to partly reduce the distance between α- and β-subunit active sites, required for MCC catalysis. Our results provide a structural framework to understand the enzymatic mechanism of eukaryotic MCCs and to assist drug discovery against trypanosome infections.