Biology subjects

Camacho-Villasana, Y.

Publications and source records attributed to Camacho-Villasana, Y..

3 recordsLinked to original sources

bioRxiv2025

Aim11 is a novel protein involved in the assembly of mitochondrial cytochrome c oxidase

Cytochrome c oxidase (CIV) is the last electron acceptor of the mitochondrial respiratory chain. In yeast, it is composed of 12 subunits, three of which are encoded in the mitochondrial genome. CIV assembly is a modular and highly regulated process that requires several specific factors. In this work, we characterized the role of Aim11 in CIV biogenesis. By high-throughput analysis, it was previously detected that Aim11 interacted with some CIV subunits, but the physiological relevance of these interactions was unknown. In the present work, we found that the{Delta} aim11 mutant exhibited reduced respiratory growth and diminished CIV activity. Using mitochondrial complexome profiling, we detected in the{Delta} aim11 mutant accumulation of intermediates of the three CIV-assembly modules, as well as reduction in supercomplexes levels. Aim11 works together with three other uncharacterized proteins: Mtc3, Gep7, and Iai11. The four proteins form a complex that we named AMIGa (Aim11-Mtc3-Iai11-Gep7 association) complex, necessary for the efficient assembly of CIV. Finally, the human protein TMEM242 was identified as Aim11 orthologue.

biochemistry↗

bioRxiv2024

Insights into the Translational Activation Mechanisms of the COX1 mRNA in Yeast Mitochondria

Mitochondrial translation is a critical regulatory step in mitochondrial genome expression. In Saccharomyces cerevisiae, translational activators are believed to bind to the 5 UTRs of their target mRNAs to position the mitochondrial ribosome at the start codon. Pet309 and Mss51 are translational activators of COX1 mRNA, which encodes subunit one of cytochrome c oxidase. Pet309 physically interacts with COX1 mRNA, but no direct interaction of Mss51 with its target mRNA has been detected. Currently, the mechanisms underlying translational activation of COX1, or any other mitochondrial gene, remain poorly understood. To explore in depth the mechanism of COX1 mRNA translational activation, we studied the association of Pet309 and Mss51 with the mitochondrial ribosome. Both Pet309 and Mss51 interact with the mitoribosome regardless of the presence of COX1 mRNA or of each other. Pet309s association with the ribosome and with COX1 mRNA depends on its N-terminal domain. These findings indicate that Pet309 and Mss51 stably interact with the mitoribosome independently of an active translation. By integrating our data with previously published research, we propose a new mechanism of COX1 mRNA translation activation. SUMMARY STATEMENTYeast mitochondrial mRNAs require translational activators by an almost unknown mechanism. Based on our findings on Mss51 and Pet309 function, we present a new model for translation of the COX1 mRNA

molecular biology↗

bioRxiv2022

The cytochrome b carboxyl-terminal region is necessary for mitochondrial Complex III assembly

Mitochondrial bc1 complex from yeast has ten subunits, but only Cytochrome b (Cytb) subunit is encoded in the mitochondrial genome. Cytb has eight transmembrane helices containing two hemes b for electron transfer. Cbp3 and Cbp6 assist Cytb synthesis, and together with Cbp4 induce Cytb hemylation. Subunits Qcr7/Qcr8 participate in the first steps of assembly, and lack of Qcr7 reduces Cytb synthesis through an assembly-feedback mechanism involving Cbp3/Cbp6. Since Qcr7 resides near the Cytb carboxyl-region, we wondered whether this region is important for Cytb synthesis/assembly. Although deletion of the Cytb C-region did not abrogate Cytb synthesis, the assembly-feedback regulation was lost, so Cytb synthesis was normal even if Qcr7 was missing. Mutants lacking the Cytb C-terminus were non-respiratory due to absence of fully assembled bc1 complex. By performing complexome profiling, we showed the existence of aberrant early-stage subassemblies in the mutant. In this work we demonstrate that the C-terminal region of Cytb is critical for regulation of Cytb synthesis and bc1 complex assembly.

biochemistry↗