Pat1 Contains Distinct Functional Domains That Promote P-Body Assembly and Activation of Decapping

Abstract

The control of mRNA degradation and translation are important aspects of gene regulation. Recent results suggest that translation repression and mRNA decapping can be intertwined and involve the formation of a quiescent mRNP, which can accumulate in cytoplasmic foci referred to as P bodies. The Pat1 protein is a key component of this complex and an important activator of decapping, yet little is known about its function. In this work, we analyze Pat1 in Saccharomyces cerevisiae function by deletion and functional analyses. Our results identify two primary functional domains in Pat1: one promoting translation repression and P-body assembly and a second domain promoting mRNA decapping after assembly of the mRNA into a P-body mRNP. In addition, we provide evidence that Pat1 binds RNA and has numerous domain-specific interactions with mRNA decapping factors. These results indicate that Pat1 is an RNA binding protein and a multidomain protein that functions at multiple stages in the process of translation repression and mRNA decapping.

ACKNOWLEDGMENTS

We thank the members of the Parker laboratory, especially Carolyn Decker, Ross Buchan, Denise Muhlrad, and Anne Webb, for valuable input, technical support, and useful discussions. We thank Maya Pilkington for her assistance and expertise with the statistical analysis. We also thank J. Cadbury for vital reagents as well as the Department of Molecular and Cellular Biology for the use of their equipment.

An NIH grant (R37 GM45443) and funds from the Howard Hughes Medical Institute supported this work.