18 - Messenger RNA Ribonucleases and mRNA Turnover in Saccharomyces cerevisiae

Abstract

This chapter discusses about messenger RNA ribonucleases and mRNA turnover in Saccharomyces cerevisiae. Among the many different functions for ribonucleases, one fundamental role is to degrade messenger RNA (mRNA). The regulated turnover of mRNA is critical in the control of gene expression. The stabilization of certain unstable mRNAs encoding protooncogenes can contribute to oncogenesis. In addition, mRNA stability can be regulated in accordance with changes in the cell growth rate, progression through the cell cycle, and changes in the cellular environment. In many cases, mRNA abundance seems to correlate more closely with mRNA half-lives than with rates of transcription. The ability to perform both advanced genetics and biochemistry with S. cerevisiae makes it well suited for dissecting the fundamental mechanisms of mRNA degradation in eukaryotes. In yeast, some mRNAs are degraded with half-lives greater than 40 min, whereas others are degraded 20 times faster. Ultimately, differential mRNA decay is determined by the regulation of cellular mRNA ribonucleases (mRNases). This chapter discusses about the pathways of mRNA decay, deadenylation-dependent decapping, nonsense-mediated decay, and endonuclease-initiated turnover pathway. The chapter also elaborates about mRNA ribonucleases, decapping enzymes, and deadenylases.