Biology subjects

Akpinar, B. A.

Publications and source records attributed to Akpinar, B. A..

3 recordsLinked to original sources

bioRxiv2024

Ribosome-binding protein 1, RRBP1, maintains peroxisomal biogenesis

Peroxisomes are single membrane-bound organelles essential for human health, yet the mechanisms of peroxisome biogenesis are not fully understood. Here using a systematic double screening approach, we identified ribosome-binding protein 1, RRBP1, as a novel peroxisome biogenesis factor in human cells. Deletion of RRBP1 in HEK293T cells led to a reduction in both peroxisome number and peroxisomal protein levels as well as in defects in processing of peroxisomal matrix proteins, such as ACOX1 and thiolase. However, cell proliferation and protein translation were not altered in cells lacking RRBP1. RRBP1 depletion did not affect peroxisome-ER contact sites, and pexophagy did not contribute to the reduction of peroxisomes in RRBP1 KO cells. Instead, in the absence of RRBP1, peroxisomal proteins were processed by proteasomal degradation, suggesting that RRBP1 plays a role in the insertion of these proteins into ER membranes and their stabilization. Altogether our results showed that RRBP1 promotes peroxisome biogenesis in human cells highlighting the power of systematic approaches in discovering novel factors of organellar biogenesis.

cell biology↗

bioRxiv2021

A novel approach to the detection of unusual mitochondrial protein change suggests hypometabolism of ancestral simians

The mitochondrial genome encodes core subunits involved in the process of oxidative phosphorylation. The sequence and structure of these mitochondria-encoded polypeptides are expected to be shaped by bioenergetic requirements linked to diet and environment. Here, we have developed a robust and effective method for highlighting phylogenetic tree edges with unexpectedly rapid, and likely consequential, substitutions within mitochondrial proteins. Further, our approach allows detection of discrete protein substitutions likely to alter enzyme performance. A survey of mammalian taxonomic groups performed using our method indicates that widely conserved residues in mitochondria-encoded proteins are more likely to rapidly mutate toward variants providing lower OXPHOS activity within specific clades. Intriguingly, our data suggest reduced cellular metabolism of ancestral anthropoids, and our findings have potential implications regarding primate encephalization. Significance StatementMitochondria harbor DNA (mtDNA) that encodes proteins important for converting food into energy. The environment and lifestyle of an organism shapes, and is shaped by, the sequences of these mitochondrial genomes. We developed a new approach for the detection of rapid functional change to proteins, and we applied our method to the mitochondria-encoded polypeptides of mammals. We found that primates displayed a general signature of relative hypometabolism that is shared with other mammals characterized by a low metabolic rate. Indications of reduced cellular metabolism extend even to the earliest anthropoids. Our findings have potential implications regarding the evolution of an enlarged primate brain.

evolutionary biology↗

bioRxiv2020

A novel phylogenetic analysis combined with a machine learning approach predicts human mitochondrial variant pathogenicity

Linking mitochondrial DNA (mtDNA) variation to clinical outcomes remains a formidable challenge. Diagnosis of mitochondrial disease is hampered by the multicopy nature and potential heteroplasmy of the mitochondrial genome, differential distribution of mutant mtDNAs among various tissues, genetic interactions among alleles, and environmental effects. Here, we describe a new approach to the assessment of which mtDNA variants may be pathogenic. Our method takes advantage of site-specific conservation and variant acceptability metrics that minimize previous classification limitations. Using our novel features, we deploy machine learning to predict the pathogenicity of thousands of human mtDNA variants. Our work demonstrates that a substantial fraction of mtDNA changes not yet characterized as harmful are, in fact, likely to be deleterious. Our findings will be of direct relevance to those at risk of mitochondria-associated metabolic disease.

evolutionary biology↗