bims-mitran 2026-03-29 papers

Issue of 2026–03–29
two papers selected by
Andreas Kohler, Umeå University

Protein Sci. 2026 Apr;35(4): e70545

The complexities of respiratory chain biogenesis and maintenance in yeast mitochondria.

Andreas Carlström, Carmela Vazquez-Calvo, Martin Ott.

Mitochondrial oxidative phosphorylation is the most efficient way of energy conversion for eukaryotic cells. It is executed by a series of high-molecular weight enzyme complexes in the inner mitochondrial membrane that were acquired during endosymbiosis at the root of eukaryotic evolution. Biogenesis of this machinery depends not only on nuclear gene expression and protein import, but also on an organelle-specific system to express a handful of proteins encoded in mitochondrial DNA. These two genetic systems cooperate for the biogenesis and maintenance of oxidative phosphorylation complexes. Here, we use the respiratory chain complex III as an example to highlight the complexities of this process. Specifically, we will describe the intricate mechanisms by which respiratory chain complexes are assembled, how the two genetic systems are coordinated and how biogenesis and function are physically separated within the inner mitochondrial membrane. To do so, we will primarily discuss findings from baker's yeast, where a wealth of recent data revealed exciting insights into these processes.

Keywords: OXPHOS; assembly; biogenesis; complex III; mitochondria; proteostasis; quality control; regulation; respiratory chain; translation

DOI: https://doi.org/10.1002/pro.70545

bioRxiv. 2026 Mar 20. pii: 2026.03.19.713005. [Epub ahead of print]

A structure-selective endonuclease drives uniparental mitochondrial DNA inheritance.

Mayu Shimomura, Hwa Young Yun, Philip C Zuzarte, Jared T Simpson, Haley D M Wyatt, Thomas R Hurd.

Maternal inheritance of mitochondrial DNA (mtDNA) is a near-universal feature of eukaryotes 1 , yet the mechanisms that ensure this by preventing paternal mtDNA inheritance have remained unclear. In both Drosophila and humans, mtDNA is actively eliminated from sperm during spermatogenesis, producing mature sperm whose mitochondria lack their genomes 2-5 . Here we identify Hotaru, a previously uncharacterized, testis-specific GIY-YIG endonuclease, as a central player in this process. We find that Hotaru is expressed in elongated spermatids, localizes to the mitochondrial matrix, and is required for paternal mtDNA elimination. In hotaru mutants, sperm retain mtDNA at levels comparable to those present before the elimination process. Genetic and biochemical analyses show that Hotaru selectively recognizes and cleaves cruciform DNA structures within the mtDNA control region. Together, these findings identify a dedicated nuclease that enforces mitochondrial genome elimination in the animal male germline and reveal that an unexpected structural feature of mtDNA serves as the molecular determinant of its destruction. By recognizing DNA structure rather than specific sequence motifs, this mechanism is inherently robust to the high mutation rate of mitochondrial genomes.

DOI: https://doi.org/10.64898/2026.03.19.713005