Biology subjects

de Barros, M. H.

Publications and source records attributed to de Barros, M. H..

2 recordsLinked to original sources

bioRxiv2026

Structural and functional insights into yeast Rqc1p, a protein required for thermotolerance with potential nuclear localization

Protein homeostasis - i.e., proteostasis - is the biological process by which the qualitative and quantitative balance of the proteome is conducted, either by preserving functionally relevant proteins or by degrading unnecessary ones. Stress conditions can modulate cellular proteostasis in order to promote cytoprotection and preserve the viability of living organisms. Among the cellular pathways already described that can play an important role in preserving biological functions by modulating proteostasis are the heat shock response and the ribosome quality control pathways. In this work, we show that the Rqc1p protein is necessary for the thermoadaptation of S. cerevisiae to heat shock, as RQC1-deficient yeast is sensitive to elevated temperatures. In silico approaches - such as multiple sequence alignment, structural analysis, and molecular dynamics simulations - confirmed earlier predictions that Rqc1p shares characteristics with the bHLH family of proteins. We also verified, through computational prediction of sub-cellular localization, that S. cerevisiae Rqc1p contains nuclear localization signals, suggesting that this protein can potentially be translocated toward the nucleus, thereby broadening its current range of recognized biological functions in this organism. Also, analysis of yeast transcriptomes subjected to heat shock showed that Rqc1p mRNA levels do not fluctuate in response to heat shock, suggesting that cellular concentrations of Rqc1p are already at optimal levels to elicit a rapid and effective response during thermal stress in S. cerevisiae.

biochemistry↗

bioRxiv2023

Dmo2p is required for Cox2p stability and plays a role in mitochondrial redox balance.

Based on available platforms of Saccharomyces cerevisiae mitochondrial proteome and other high throughput studies, we identified the yeast gene DMO2 with a profile of genetic and physical interactions that indicate a putative role in mitochondrial respiration. Dmo2p is a homolog to human DMAC1 with two conserved cysteines in a Cx2C motif. Here, we localized Dmo2p in the mitochondrial inner membrane with the conserved cysteines facing the intermembrane space. The observed phenotypes of the dmo2 null mutant indicate a general function in cellular stress response; the mutant displayed poor growth on non-fermentative media at 37{degrees}C, and in oleate, it is more sensitive to heat and oxidative stress while its overexpression confers resistance to some of the tested stressors. Dmo2p topology and modeled structure suggested a functional redox role for the Cx2C motif sustained by site-directed mutagenesis of both cysteine residues. The respiratory deficiency of dmo2 mutants at 37{degrees}C led to a reduction in cytochrome c oxidase activity (COX) and the formation of bc1-COX supercomplexes; we also observed a rapid turnover of Cox2p, the subunit two of the cytochrome c oxidase complex that harbors the binuclear CuA center. Moreover, Dmo2p co-immunoprecipitated with Cox2p and components of CuA center maturation such as Sco1p and Sco2p; and finally, DMO2 overexpression can suppress cox23 respiratory deficiency, a mutant that has the mitochondrial copper homeostasis impaired. Overall, our data suggest that Dmo2p is required for Cox2p maturation, potentially by aiding proteins involved in copper transport and incorporation into Cox2p.

molecular biology↗