Professor Joseph Falke
Department of Chemistry and Biochemistry
University of Colorado
Boulder, CO

Monday, March 9, 2015
3:00 pm (CT)
3269 Beckman Institute

Abstract

Bacterial swimming is guided by an ultrasensitive, ultrastable, hexagonal chemosensory array that can sense as few as 1-2 attractant molecules, enabling cell migration to a wound or other food source. The core unit of this hexagonal array is multi-protein complex comprised of 2 receptor oligomers (each a trimer of homodimers), 1 protein kinase homodimer, and 2 adaptor protein monomers. Signals are transduced from the receptor periplasmic ligand binding domain to the cytoplasmic receptor tip that controls the activity of the tightly bound kinase in the same core unit, and ultimately spread out into the highly cooperative array. A growing body of evidence is revealing the large scale architecture of the lattice, yet questions remain about the identities of the packing interfaces between core components and about the nature of signal transduction within and between core units. We are reconstituting functional, intact core units on isolated bacterial membranes, yielding assemblies ranging in size from individual core units to small arrays. Biochemical and biophysical studies are providing new insights into the assembly kinetics and structure of these reconstituted core complexes, and into the molecular mechanisms underlying receptor-mediated kinase on-off switching.