CeBiTec Colloquium: 2009/02/02 Dr. Antje Berken, Max-Planck-Institute of Molecular Physiology, Dortmund

2009/02/02, 17:15

CeBiTec Laboratory Building, Room G2-104

Molecular mechanisms of Rho-regulated cell functions in plants

Abstract:
Rho-related ROP proteins are molecular switches which control essential plant cell functions including polar growth and differentiation, and reactions to diverse environmental stimuli. ROPs switch between GTP- and GDP-bound conformations by strictly regulated nucleotide exchange and GTP-hydrolysis, and only the active GTP-form interacts with downstream effectors to ultimately provoke a biological response. However, the mode of action of the engaged regulators and effectors as well as their upstream and downstream interaction partners are still largely unknown. As opposed to analogous systems in animals and fungi, plants use specific GTPase-activating proteins (RopGAPs) with a unique domain composition, novel guanine nucleotide exchange factors (RopGEFs) as a probable link to cell surface receptors, and exceptional effector molecules which partly act as adapters connecting ROPs to yet unknown downstream targets. Our current work aims toresolve the molecular mechanisms and reaction cascades involved in ROP-dependent growth of pollen tubes during plant sexual reproduction. We address the structure and function of the unusual RopGAPs, RopGEFs and effectors, and study the upstream and downstream pathways linking ROPs to receptor-like kinases and their extracellular ligands as well as to actin filaments, microtubules and calcium signaling inside the cell.