Genome-wide mutagenesis resulting from topoisomerase 1-processing of unrepaired ribonucleotides in DNA
| Autor: | Zhi-Xiong Zhou, Scott A. Lujan, Adam B. Burkholder, Jessica S. Williams, Alan B. Clark, Thomas A. Kunkel, David C. Fargo |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2019 |
| Předmět: |
Genome instability
Ribonucleotide Saccharomyces cerevisiae Proteins DNA Repair DNA polymerase Base pair Ribonucleotide excision repair DNA-Directed DNA Polymerase Saccharomyces cerevisiae Biochemistry Article Genomic Instability 03 medical and health sciences chemistry.chemical_compound 0302 clinical medicine Mutation Rate Trinucleotide Repeats Dinucleotide Repeats Molecular Biology 030304 developmental biology Genetics 0303 health sciences biology Cell Biology Ribonucleotides Deletion Mutagenesis chemistry DNA Topoisomerases Type I 030220 oncology & carcinogenesis biology.protein Trinucleotide repeat expansion DNA Gene Deletion |
| Zdroj: | DNA Repair (Amst) |
| Popis: | Ribonucleotides are the most common non-canonical nucleotides incorporated into DNA during replication, and their processing leads to mutations and genome instability. Yeast mutation reporter systems demonstrate that 2-5 base pair deletions (Δ2-5bp) in repetitive DNA are a signature of unrepaired ribonucleotides, and that these events are initiated by topoisomerase 1 (Top1) cleavage. However, a detailed understanding of the frequency and locations of ribonucleotide-dependent mutational events across the genome has been lacking. Here we present the results of genome-wide mutational analysis of yeast strains deficient in Ribonucleotide Excision Repair (RER). We identified mutations that accumulated over thousands of generations in strains expressing either wild-type or variant replicase alleles (M644G Pol e, L612M Pol δ, L868M Pol α) that confer increased ribonucleotide incorporation into DNA. Using a custom-designed mutation-calling pipeline called muver (for mutationes verificatae), we observe a number of surprising mutagenic features. This includes a 24-fold preferential elevation of AG and AC relative to AT dinucleotide deletions in the absence of RER, suggesting specificity for Top1-initiated deletion mutagenesis. Moreover, deletion rates in di- and trinucleotide repeat tracts increase exponentially with tract length. Consistent with biochemical and reporter gene mutational analysis, these deletions are no longer observed upon deletion of TOP1. Taken together, results from these analyses demonstrate the global impact of genomic ribonucleotide processing by Top1 on genome integrity. |
| Databáze: | OpenAIRE |
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