Poster: Late and Moved Abstracts

Abs # 1439: Novel protein Ser/Thr phosphatases in plants

Presenter:	Kutuzov, Mikhail , kutuzov@uic.edu
Authors	Kutuzov, Mikhail  (A) (B)  Andreeva, Alexandra  (C) (D)
Affiliations:	(A): University of Illinois at Chicago (B): DBMS, CEA-Grenoble, France (C): RBMS, Oxford Brookes University, UK (D): SMB, Washington State University

Reversible protein phosphorylation on Ser/Thr residues is an indispensable way of regulation of a great number of cellular functions. Our work has identified several novel groups of plant protein Ser/Thr phosphatases of the PPP family, one of the two known families of Ser/Thr phosphatases. Most of these phosphatases are specific for plants or shared with organisms that have evolutionary links with plants. PP7, probably present throughout land plants, have no close relatives outside Viridiplantae and are distantly related to PPEF phosphatases from animals and some unicellular organisms. Detailed characterization of PP7 is presented on a separate poster (1464). PPKL (protein phosphatases with kelch-like repeat domains) are related to PP1 but have N-terminal kelch-like repeat domains likely to mediate protein-protein interactions. In many proteins, these domains are known to mediate interaction with actin. Unexpectedly, we also identified two groups of "bacterial-like" PPP phosphatases in plants, strikingly different from "classical" eukaryotic PPPs. Probable origin of one of these groups is by horizontal gene transfer from rhizobia. We were able to define a previously unrecognized structural motif that distinguishes Ser/Thr-specific eukaryotic and archaeal PPP phosphatases from from bacterial PPPs, which have broader specificity.