Arguello T, Köhrer C, RajBhandary UL, Moraes CT. Mitochondrial methionyl
N-formylation affects steady-state levels of oxidative phosphorylation complexes and their organization into supercomplexes.
J Biol Chem 2018;
293:15021-15032. [PMID:
30087118 DOI:
10.1074/jbc.ra118.003838]
[Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2018] [Revised: 08/02/2018] [Indexed: 12/20/2022] Open
Abstract
N-Formylation of the Met-tRNAMet by the nuclearly encoded mitochondrial methionyl-tRNA formyltransferase (MTFMT) has been found to be a key determinant of protein synthesis initiation in mitochondria. In humans, mutations in the MTFMT gene result in Leigh syndrome, a progressive and severe neurometabolic disorder. However, the absolute requirement of formylation of Met-tRNAMet for protein synthesis in mammalian mitochondria is still debated. Here, we generated a Mtfmt-KO mouse fibroblast cell line and demonstrated that N-formylation of the first methionine via fMet-tRNAMet by MTFMT is not an absolute requirement for initiation of protein synthesis. However, it differentially affected the efficiency of synthesis of mtDNA-coded polypeptides. Lack of methionine N-formylation did not compromise the stability of these individual subunits but had a marked effect on the assembly and stability of the OXPHOS complexes I and IV and on their supercomplexes. In summary, N-formylation is not essential for mitochondrial protein synthesis but is critical for efficient synthesis of several mitochondrially encoded peptides and for OXPHOS complex stability and assembly into supercomplexes.
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