Global Analysis of Pub1p Targets Reveals a Coordinate Control of Gene Expression through Modulation of Binding and Stability

Abstract

Regulation of mRNA turnover is an important cellular strategy for posttranscriptional control of gene expression, mediated by the interplay of cis-acting sequences and associated trans-acting factors. Pub1p, an ELAV-like yeast RNA-binding protein with homology to T-cell internal antigen 1 (TIA-1)/TIA-1-related protein (TIAR), is an important modulator of the decay of two known classes of mRNA. Our goal in this study was to determine the range of mRNAs whose stability is dependent on Pub1p, as well as to identify specific transcripts that directly bind to this protein. We have examined global mRNA turnover in isogenic PUB1 and pub1Δ strains through gene expression analysis and demonstrate that 573 genes exhibit a significant reduction in half-life in a pub1Δ strain. We also examine the binding specificity of Pub1p using affinity purification followed by microarray analysis to comprehensively distinguish between direct and indirect targets and find that Pub1p significantly binds to 368 cellular transcripts. Among the Pub1p-associated mRNAs, 53 transcripts encoding proteins involved in ribosomal biogenesis and cellular metabolism are selectively destabilized in the pub1Δ strain. In contrast, genes involved in transporter activity demonstrate association with Pub1p but display no measurable changes in transcript stability. Characterization of two candidate genes, SEC53 and RPS16B, demonstrate that both Pub1p-dependent regulation of stability and Pub1p binding require 3′ untranslated regions, which harbor distinct sequence motifs. These results suggest that Pub1p binds to discrete subsets of cellular transcripts and posttranscriptionally regulates their expression at multiple levels.

SUPPLEMENTAL MATERIAL

Supplemental material for this article may be found at http://mcb.asm.org/.

ACKNOWLEDGMENTS

We thank the entire CAG staff, especially Saleena Ghanny, Anthony Galante, and Virginie Aris, for assistance with microarray experiments and analysis. We thank the members of the Peltz lab for valuable comments and Andre Gerber for yeast strains and protocols. We also thank Yulei Wang for helpful discussions and Maurice Swanson for the kind gift of the PUB1 antibody.

This work is supported by a grant from the National Institutes of Health (GM 058276 and AI 057596) to S.W.P. C.J.W. was supported by the American Heart Association (award 0130470T).