Originally published as Genetics Published Articles Ahead of Print on November 17, 2008.

Genetics, Vol. 181, 93-103, January 2009, Copyright © 2009
doi:10.1534/genetics.108.092601

Stm1 Modulates mRNA Decay and Dhh1 Function in Saccharomyces cerevisiae

Vidya Balagopal and Roy Parker1

Department of Molecular and Cellular Biology and Howard Hughes Medical Institute, University of Arizona, Tucson, Arizona 85721-0206

1 Corresponding author: Department of Molecular and Cellular Biology and Howard Hughes Medical Institute, University of Arizona, 1007 E. Lowell St., Tucson, AZ 85721-0206.
E-mail: rrparker{at}u.arizona.edu

The control of mRNA degradation and translation are important for the regulation of gene expression. mRNA degradation is often initiated by deadenylation, which leads to decapping and 5'–3' decay. In the budding yeast Saccharomyces cerevisae, decapping is promoted by the Dhh1 and Pat1 proteins, which appear to both inhibit translation initiation and promote decapping. To understand the function of these factors, we identified the ribosome binding protein Stm1 as a multicopy suppressor of the temperature sensitivity of the pat1{Delta} strain. Stm1 loss-of-function alleles and overexpression strains show several genetic interactions with Pat1 and Dhh1 alleles in a manner consistent with Stm1 working upstream of Dhh1 to promote Dhh1 function. Consistent with Stm1 affecting Dhh1 function, stm1{Delta} strains are defective in the degradation of the EDC1 and COX17 mRNAs, whose decay is strongly affected by the loss of Dhh1. These results identify Stm1 as an additional component of the mRNA degradation machinery and suggest a possible connection of mRNA decapping to ribosome function.