Structural Features of Transmembrane Signaling in Plants

University Of Missouri-Columbia, Columbia MO

Investigators

Abstract

Switching of signals at the surface of plant cells controls plant development, hormone response, avoidance of self-pollination, and disease resistance. Transmembrane signaling in plants is exemplified by the interactions of the receptor-like kinase (RLK) CLAVATA1 with kinase-associated protein phosphatase (KAPP). This pair interacts on the inner surface of the plasma membrane to guide the development of the shoot and flower meristems of the model plant Arabidopsis. The fundamental question of how the KAPP FHA domain interacts with an RLK kinase domain will be investigated in this project. The FHA domain is a newly described class of phosphoserine / phosphothreonine-binding domain which is ubiquitous among eukaryotes in diverse protein-protein signaling contexts. No three-dimensional atomic structures of KAPP or of an RLK have been reported. NMR will be used to determine high quality structures of the distinctive FHA domain of KAPP in two forms: free and bound to a phosphopeptide. Sequence determinants of the specificity of phosphopeptide interactions with the KAPP FHA domain will be explored using site-directed mutagenesis, screening of phosphoser/thr peptide binding, and thermodynamics of the binding of phosphopeptides most avid for the FHA domain. To further probe how KAPP interacts with CLAVATA1, the structure of the serine kinase domain of this RLK will be modeled. The training of PhD students will be enhanced by exposure to complementary plant genetics studies in the lab of John Walker and to protein modeling in the lab of Jeff Skolnick. This project will provide insights into how a class of plant signaling proteins interacts specifically during the process of signal switching. It will also add perspective to FHA-mediated protein-protein interactions in other organisms.