Mrx6 binds the Lon protease Pim1 N-terminal domain to confer selective substrate specificity and regulate mtDNA copy number.

ABSTRACT: Mitochondrial DNA (mtDNA) copy number regulation remains incompletely understood, despite its importance in cellular function. In Saccharomyces cerevisiae, Mrx6 belongs to the Pet20-domain-containing protein family, consisting of Mrx6, Pet20, and Sue1. Notably, absence of Mrx6 leads to increased mtDNA copy number. Here, we identify the C-terminus of Mrx6 as essential for its stability and interaction with the mitochondrial matrix protein Mam33. Deletion of Mam33 mimics the effect of Mrx6 loss, resulting in elevated mtDNA copy number. Bioinformatics, mutational analyses, and immunoprecipitation studies corroborate that a subcomplex of Mam33 and Mrx6 trimers interacts with the substrate recognition domain of the conserved mitochondrial Lon protease Pim1 through a bipartite domain in the Pet2

SUBMITTER: Schrott S 

PROVIDER: S-EPMC12802967 | biostudies-literature | 2026 Jan

REPOSITORIES: biostudies-literature