Poster abstracts

Poster number 85 submitted by Wai Kit Ma

Inhibition of a DEAD-box RNA helicase Dbp2 by the mRNA binding protein Yra1

Wai Kit Ma (Department of Biochemistry, Purdue University, West Lafayette, Indiana), Sara C. Cloutier (Department of Biochemistry, Purdue University, West Lafayette, Indiana), Elizabeth J. Tran (Department of Biochemistry, Purdue University, West Lafayette, Indiana)

Abstract:
RNA structure and ribonucleoprotein (RNP) complex formation are critical for eukaryotic gene expression. One class of enzymes called DEAD-box RNA helicases play fundamental roles in remodeling RNA and RNP structure in every aspect of RNA metabolism. Nevertheless, how the biochemical activity of these enzymes is connected to the biological function remains elusive. To define the precise roles of individual DEAD-box proteins, our laboratory recently demonstrated that DEAD-box protein Dbp2 functions in nuclear gene expression steps in Saccharomyces cerevisiae. We will present evidence that Dbp2 interacts physically with the mRNA binding protein Yra1. Moreover, we will show that Dbp2 is required for efficient assembly of mRNA-binding proteinYra1, Nab2, and Mex67 onto poly(A)+ RNA. In addition, we will demonstrate that Dbp2 is an active RNA helicase in vitro and that Yra1 reduces the unwinding activity of Dbp2. We propose that Dbp2 unwinds secondary structure within mRNA to facilitate efficient messenger ribonucleoprotein (mRNP) assembly. Once the mRNP is properly assembled, Yra1 then inhibits Dbp2 to prevent further rearrangement of the mRNP. This provides a novel mechanism for regulation of DEAD-box proteins in RNP assembly.

Keywords: DEAD-box protein, mRNP assembly, mRNA binding protein