Regulation of Protein Phosphatase 2A Activity in Arabidopsis by the RCN1 Protein

Brown University, Providence RI

Investigators

Abstract

Reversible protein phosphorylation, the enzymatic addition and removal of phosphoryl groups on target proteins, modulates the biological activities of a large fraction of the proteins expressed in eukaryotic cells. Protein phosphorylation levels in cells are determined by a highly dynamic and tightly regulated balance between the activities of protein kinases, which add phosphoryl modifications to target proteins, and protein phosphatases, which remove those phosphoryl modifications. The serine/threonine protein phosphatase 2A (PP2A) constitutes an abundant population of enzymes that play crucial roles in the regulation of growth and development. This project focuses on the analysis of PP2A roles in controlling the production of ethylene, a key regulator of growth, defense responses, reproduction, ripening and senescence in plants. Using genetic and biochemical tools, the investigators will define the mechanism by which PP2A modulates ethylene production. Identification of the target for PP2A regulation in this pathway will be a significant advance not only for our understanding of the regulation of ethylene biosynthesis, but also for our ongoing analysis of PP2A function in plants. The cardinal challenge in current protein phosphatase research is the identification of bona fide in vivo substrates. Furthermore, because PP2A modulates several hormone response pathways and is required for normal stress responses, better understanding of the regulation of PP2A activity levels may allow manipulation of plant growth properties and stress tolerance. The Arabidopsis system provides a powerful model for this work because of the existing array of genetic and genomic resources for analysis of ethylene biosynthesis and PP2A function in plants. The proposed work provides excellent training opportunities for students at both the graduate and undergraduate levels in a project with broad biological and agronomic significance.