Author contributions DCJ coordinated all analyses, isolated DNA for sequencing, analysed and filtered SNP calls, conducted diversity analysis and GWAS and drafted the manuscript. CR produced phenotype data for growth on various solid media and growth rates in liquid media. AR conducted analysis of dating using mitochondrial data. DS conducted GWAS. MP analysed all phenotype data. TM identified LTR transposon insertions and analysed transposon insertion data. FXM conducted crosses for analysis of spore viability ZI produced indel calls with Cortex. WL conducted analysis of recombination rate, linkage disequilibrium decay and PCA for distance between strains. TMKC assisted with phenotype and population analysis. RP analysed Cortex and GATK indel calls. MM conducted amino acid profiling. JLDL and AC produced automated measures of cell morphology. SB aligned reads and produced GATK SNP calls. GH analysed population structure using fineSTRUCTURE. BO'F estimated the TMRCA from the nuclear genome using ACG. TK identified LTR transposon insertions JTS produced de novo assemblies. LB developed the custom Workspace workflow Spotsizer. BT assisted with sequence analysis. DAB assisted with analysis of novel genes. TS assisted with strain verification. SC produced images of wild strains and assisted with strain verification. JEEUH assisted with SNP validation. LvT and MT assisted with LTR validation. LJ and JL assisted with manual measures of cell morphology and FACS. SA produced gene expression data. MF, KM and ND assisted with sequencing. WB initiated and assisted with strain collection. JH coordinated manual measures of cell morphology and FACS. RECS coordinated automated measures of cell morphology. MR coordinated amino acid profiling. NM conducted analysis of recombination, linkage disequilibrium and advised on aspects of diversity and GWAS. DJB advised on GWAS. RD facilitated sequencing. JB contributed to the initiation and development of the project and financed the JB laboratory. AccessionsSequence data are archived in the European Nucleotide Archive (www.ebi.ac.uk/ena/), Study Accessions PRJEB2733 and PRJEB6284 (Supplementary Table 7). All SNPs and indels were submitted to NCBI dbSNP (www.ncbi.nlm.nih.gov/SNP/). Accessions are 974514578-974688138 (SNPs) and 974702618-974688139 (indels). Europe PMC Funders Group AbstractNatural variation within species reveals aspects of genome evolution and function. The fission yeast Schizosaccharomyces pombe is an important model for eukaryotic biology, but researchers typically use one standard laboratory strain. To extend the utility of this model, we surveyed the genomic and phenotypic variation in 161 natural isolates. We sequenced the genomes of all strains, revealing moderate genetic diversity (π = 3 ×10 −3 ) and weak global population structure. We estimate that dispersal of S. pombe began within human antiquity (~340 BCE), and ancestors of these strains reached the Americas at ~1623 CE. We quantified 74 traits, revealing substantial heritable phenotypic diversity. We cond...

SummarySeveral metals and metalloids profoundly affect biological systems, but their impact on the proteome and mechanisms of toxicity are not fully understood. Here, we demonstrate that arsenite causes protein aggregation in Saccharomyces cerevisiae. Various molecular chaperones were found to be associated with arsenite-induced aggregates indicating that this metalloid promotes protein misfolding. Using in vivo and in vitro assays, we show that proteins in the process of synthesis/folding are particularly sensitive to arsenite-induced aggregation, that arsenite interferes with protein folding by acting on unfolded polypeptides, and that arsenite directly inhibits chaperone activity. Thus, folding inhibition contributes to arsenite toxicity in two ways: by aggregate formation and by chaperone inhibition. Importantly, arsenite-induced protein aggregates can act as seeds committing other, labile proteins to misfold and aggregate. Our findings describe a novel mechanism of toxicity that may explain the suggested role of this metalloid in the etiology and pathogenesis of protein folding disorders associated with arsenic poisoning.

RNA molecules undergo a vast array of chemical post-transcriptional modifications (PTMs) that can affect their structure and interaction properties. In recent years, a growing number of PTMs have been successfully mapped to the transcriptome using experimental approaches relying on high-throughput sequencing. Oxford Nanopore direct-RNA sequencing has been shown to be sensitive to RNA modifications. We developed and validated Nanocompore, a robust analytical framework that identifies modifications from these data. Our strategy compares an RNA sample of interest against a non-modified control sample, not requiring a training set and allowing the use of replicates. We show that Nanocompore can detect different RNA modifications with position accuracy in vitro, and we apply it to profile m6A in vivo in yeast and human RNAs, as well as in targeted non-coding RNAs. We confirm our results with orthogonal methods and provide novel insights on the co-occurrence of multiple modified residues on individual RNA molecules.

Reactive oxygen species (ROS) are linked to various degenerative conditions, but it is unclear which molecular target(s) may be the cell's primary “Achilles’ heel,” accounting for inhibition by ROS. Our results indicate that the FeS protein Rli1p, with essential and conserved functions in protein synthesis, is an important target of ROS toxicity.

Chromium toxicity

Competitive growth between over 6,000 heterozygous yeast mutants in the presence of chromium together with microarray-based screens showed that proteasomal activity is crucial for cellular chromium resistance.

Protein aggregation is a widespread phenomenon in cells and associated with pathological conditions. Yet, little is known about the rules that govern protein aggregation in living cells. In this study, we biochemically isolated aggregation-prone proteins and used computational analyses to identify characteristics that are linked to physiological and arsenite-induced aggregation in living yeast cells. High protein abundance, extensive physical interactions, and certain structural properties are positively correlated with an increased aggregation propensity. The aggregated proteins have high translation rates and are substrates of ribosome-associated Hsp70 chaperones, indicating that they are susceptible for aggregation primarily during translation/folding. The aggregation-prone proteins are enriched for multiple chaperone interactions, thus high protein abundance is probably counterbalanced by molecular chaperones to allow soluble expression in vivo. Our data support the notion that arsenite interferes with chaperone activity and indicate that arsenite-aggregated proteins might engage in extensive aberrant protein–protein interactions. Expression of aggregation-prone proteins is down-regulated during arsenite stress, possibly to prevent their toxic accumulation. Several aggregation-prone yeast proteins have human homologues that are implicated in misfolding diseases, suggesting that similar mechanisms may apply in disease- and non-disease settings.

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Peroxiredoxins (Prxs) are ubiquitous antioxidants that protect cells against oxidative stress. We show that the yeast Tsa1/Tsa2 Prxs colocalize to ribosomes and function to protect the Sup35 translation termination factor against oxidative stress-induced formation of its