alternative 3′ pre-mrna processing in saccharomyces cerevisiae is modulated by nab4hrp1 in vivo酿酒酵母中选择3u2032pre-mrna处理由nab4hrp1体内调制.pdfVIP

PLoS BIOLOGY Alternative 39 Pre-mRNA Processing in Saccharomyces cerevisiae Is Modulated by Nab4/Hrp1 In Vivo * Karen S. Kim Guisbert, Hao Li, Christine Guthrie Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, California, United States of America The Saccharomyces cerevisiae RNA-binding protein Nab4/Hrp1 is a component of the cleavage factor complex required for 3 9 pre-mRNA processing. Although the precise role of Nab4/Hrp1 remains unclear, it has been implicated in correct positioning of the cleavage site in vitro. Here, we show that mutation or overexpression of NAB4/HRP1 alters polyA cleavage site selection in vivo. Using bioinformatic analysis, we identified four related motifs that are statistically enriched in Nab4-associated transcripts; each motif is similar to the known binding site for Nab4/Hrp1. Site-directed mutations in predicted Nab4/Hrp1 binding elements result in decreased use of adjacent cleavage sites. Additionally, we show that the nab4-7 mutant displays a striking resistance to toxicity from excess copper. We identify a novel target of alternative 39 pre-mRNA processing, CTR2, and demonstrate that CTR2 is required for the copper resistance phenotype in the nab4-7 strain. We propose that alternative 39 pre-mRNA processing is mediated by a Nab4-based mechanism and that these alternative processing events could help control gene expression as part of a physiological response in S. cerevisiae. Citation: Kim Guisbert KS, Li H, Guthrie C (2007) Alternative 39 pre-mRNA processing in Saccharomyces cerevisiae is modulated by Nab4/Hrp1 in vivo. PLoS Biol 5(1): e6. doi:10. 1371/journal.pbio.0050006 Introduction