Functions of Protein Phosphatase 2A Isoforms in Arabidopsis Development

Brown University, Providence RI

Investigators

Abstract

Reversible protein phosphorylation is a fundamental regulatory mechanism in organisms ranging from prokaryotes to multicellular eukaryotes, and is involved in the regulation of a variety of cellular processes. Protein phosphorylation is tightly regulated by several mechanisms that maintain a balance between the activities of phosphorylating and dephosphorylating enzymes. The biological functions of protein phosphatase 2A (PP2A) in Arabidopsis will be analyzed using mutations that will be isolated in the course of the project. In transgenic plants, wild-type and dominant-defective PP2A-C subunits will be expressed under control of inducible promoters. The effects of expressing these PP2A-C alleles will be analyzed both in a wild-type background and in a mutant, which exhibits reduced PP2A activity. A dominant-defective approach will be combined with more conventional loss-of-function mutational analysis, through PCR-based screens to isolate T-DNA insertion mutations in two of the five known Arabidopsis PP2A-C genes. Plants carrying dominant-defective or null PP2A-C alleles will be examined for visible and conditional phenotypes, with particular attention to effects on seedling growth and development. These experiments will investigate the effects of blocking PP2A functions, and will identify both specific and shared PP2A functions. The goal of these studies is an improved understanding of the roles of PP2A subunits and their interactions in vivo.