Hrq1, the fungal orthologue of human RECQL4, is important in preventing chronological aging in Saccharomyces cerevisiae

초록

Maintenance of genome stability in eukaryotes involves a number of conserved proteins, including RecQ helicases that play multiple roles at various steps in homologous recombination. Sgs1 has been described as the only RecQ helicase in lower eukaryotes. However, recent studies revealed presence of a second RecQ helicase, Hrq1, which is homologous to human RECQL4. Here we show that HRQ1 is a functional gene in Saccharomyces cerevisiae that cooperates with SGS1 to prevent chronological aging. Yeast cells lacking HRQ1 showed normal growth and similar replicative senescence to that of wild-type cells, but exhibited slightly shortened chronological life span (CLS). In addition, deletion of SGS1 led to significant CLS decrease in hrq1 mutant, indicating that both genes are important in preventing chronological aging in S. cerevisiae. We also found that spontaneous canr mutation frequency increased rapidly with age in hrq1 backgroud. The mutant cells also exhibited increased recombination frequency between sister chromatids. These observations suggest that Hrq1 may play important roles in maintenance of genome stability by suppressing mutations and illegitimate recombination in yeast.