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Mild phenotypes and proper supercomplex assembly in human cells carrying the homoplasmic m.15557G > A mutation in cytochrome b gene
Author(s) -
Iommarini Luisa,
Ghelli Anna,
Leone Giulia,
Tropeano Concetta Valentina,
Kurelac Ivana,
Amato Laura Benedetta,
Gasparre Giuseppe,
Porcelli Anna Maria
Publication year - 2018
Publication title -
human mutation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 162
eISSN - 1098-1004
pISSN - 1059-7794
DOI - 10.1002/humu.23350
Subject(s) - biology , ubiquinol , cytochrome b , respiratory chain , coenzyme q – cytochrome c reductase , cytochrome c , mitochondrial dna , mitochondrion , genetics , cytochrome , mutant , biochemistry , gene , microbiology and biotechnology , enzyme
Abstract Respiratory complex III (CIII) is the first enzymatic bottleneck of the mitochondrial respiratory chain both in its native dimeric form and in supercomplexes. The mammalian CIII comprises 11 subunits among which cytochrome b is central in the catalytic core, where oxidation of ubiquinol occurs at the Qo site. The Qo‐ or PEWY‐motif of cytochrome b is the most conserved through species. Importantly, the highly conserved glutamate at position 271 (Glu271) has never been studied in higher eukaryotes so far and its role in the Q‐cycle remains debated. Here, we showed that the homoplasmic m.15557G > A/ MT‐CYB , which causes the p.Glu271Lys amino acid substitution predicted to dramatically affect CIII, induces a mild mitochondrial dysfunction in human transmitochondrial cybrids. Indeed, we found that the severity of such mutation is mitigated by the proper assembly of CIII into supercomplexes, which may favor an optimal substrate channeling and buffer superoxide production in vitro.