Molecular basis of diseases induced by the mitochondrial DNA mutation m.9032T>C.
Hum Mol Genet
; 32(8): 1313-1323, 2023 04 06.
Article
in En
| MEDLINE
| ID: mdl-36434790
ABSTRACT
The mitochondrial DNA mutation m.9032T>C was previously identified in patients presenting with NARP (Neuropathy Ataxia Retinitis Pigmentosa). Their clinical features had a maternal transmission and patient's cells showed a reduced oxidative phosphorylation capacity, elevated reactive oxygen species (ROS) production and hyperpolarization of the mitochondrial inner membrane, providing evidence that m.9032T>C is truly pathogenic. This mutation leads to replacement of a highly conserved leucine residue with proline at position 169 of ATP synthase subunit a (L169P). This protein and a ring of identical c-subunits (c-ring) move protons through the mitochondrial inner membrane coupled to ATP synthesis. We herein investigated the consequences of m.9032T>C on ATP synthase in a strain of Saccharomyces cerevisiae with an equivalent mutation (L186P). The mutant enzyme assembled correctly but was mostly inactive as evidenced by a > 95% drop in the rate of mitochondrial ATP synthesis and absence of significant ATP-driven proton pumping across the mitochondrial membrane. Intragenic suppressors selected from L186P yeast restoring ATP synthase function to varying degrees (30-70%) were identified at the original mutation site (L186S) or in another position of the subunit a (H114Q, I118T). In light of atomic structures of yeast ATP synthase recently described, we conclude from these results that m.9032T>C disrupts proton conduction between the external side of the membrane and the c-ring, and that H114Q and I118T enable protons to access the c-ring through a modified pathway.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Protons
/
Saccharomyces cerevisiae
Limits:
Humans
Language:
En
Journal:
Hum Mol Genet
Journal subject:
BIOLOGIA MOLECULAR
/
GENETICA MEDICA
Year:
2023
Document type:
Article
Affiliation country:
Poland