Multiple nutritional phenotypes of fission yeast mutants defective in genes encoding essential mitochondrial proteins

Abstract

Mitochondria are essential for regulation of cellular respiration, energy production, small molecule metabolism, anti-oxidation and cell ageing, among other things. While the mitochondrial genome contains a small number of protein-coding genes, the great majority of mitochondrial proteins are encoded by chromosomal genes. In the fission yeast Schizosaccharomyces pombe , 770 proteins encoded by chromosomal genes are located in mitochondria. Of these, 195 proteins, many of which are implicated in translation and transport, are absolutely essential for viability. We isolated and characterized eight temperature-sensitive ( ts ) strains with mutations in essential mitochondrial proteins. Interestingly, they are also sensitive to limited nutrition (glucose and/or nitrogen), producing low-glucose-sensitive and ‘super-housekeeping' phenotypes. They fail to produce colonies under low-glucose conditions at the permissive temperature or lose cell viability under nitrogen starvation at the restrictive temperature. The majority of these ts mitochondrial mutations may cause defects of gene expression in the mitochondrial genome. mrp4 and mrp17 are defective in mitochondrial ribosomal proteins. ppr3 is defective in rRNA expression, and trz2 and vrs2 are defective in tRNA maturation. This study promises potentially large dividends because mitochondrial quiescent functions are vital for human brain and muscle, and also for longevity.

PomBase: a Global Core Biodata Resource—growth, collaboration, and sustainability

“…2021 ) and in the study of the conserved mechanisms affecting aging and lifespan ( Romila et al . 2021 ; Uehara et al . 2021 ; Mori et al .…”

In quiescent G0 phase,Schizosaccharomyces pombeMis4 ensures full nuclear separation during the subsequent M phase

“…shk genes are apparently required for maintenance of cell viability in both proliferating and quiescent cells, whereas gze genes are essential only in quiescent cells. 40 shk genes and 85 gze genes have been so far identified (Hayashi et al, 2018; Nakazawa et al, 2018; Sajiki et al, 2009; Sajiki et al, 2018; Uehara et al, 2021). As diverse molecular roles of these gene products are predicted from annotations in POMBASE (https://www.pombase.org), a wide variety of molecules function together to enable cells to enter or exit G0 phase.…”

In fission yeast, 65 non-essential mitochondrial proteins related to respiration and stress become essential in low-glucose conditions

“…From a genome-wide analysis of genes essential for cell viability [ 13 ], one of the most striking differences between S. cerevisiae and S. pombe is the number of essential chromosomal genes related to mitochondrial function. For example, 96 essential S. pombe genes are required for translation of genes encoded in mtDNA, whereas only six budding yeast orthologues are essential [ 14 ]. Mitochondrial genome organization [ 11 , 15 ] in higher eukaryotic organisms is similar to that of S. pombe ; therefore, S. pombe mitochondria may serve as a useful model.…”

“…Combined with descriptions in the fission yeast genome database (Pombase, [ 16 ]), comprehensive protein localization analysis [ 17 ] showed that 770 fission yeast proteins comprising approximately 15% of all proteins encoded by the genome are thought to be located in mitochondria and/or to possess mitochondrial functions. As discussed in our previous study [ 14 ], approximately 25% of them (195 proteins) are required for cell survival in vegetative conditions.…”