CSSB Seminar Series - BRIAN CRANE
Abstract:
Bacterial chemotaxis, the ability of bacteria to adapt their motion to external stimuli, has long stood as a model system for understanding transmembrane signaling, intracellular information transfer, and motility. The signaling network of chemotaxis involves two large multi-component transmembrane assemblies: (1) the receptor:kinase array that senses stimuli and generates a diffusible phosphorylated messenger molecule (CheY-P) as output, and (2) the flagella motor that rotates the filament clockwise or counterclockwise in response to CheY-P. Transmembrane chemoreceptors, the histidine kinase CheA, and the receptor-coupling protein CheW are linked through cooperative interactions that can extend through thousands of molecules in a single membrane array. To address these systems, structural and biochemical studies have been undertaken on isolated components, reconstituted complexes, and native receptor assemblies. Engineered chemoreceptor mimetics of natural receptor oligomers have proven particularly useful for studying kinase activation. Evidence will be presented to support the notion that changes to both molecular conformation and dynamics are necessary to propagate signals in these systems. Attention will also be drawn to the pathogenic Spirochaetes and their unique properties with respect to chemotaxis, which include novel chemical cross-linking reactions in their periplasmic flagella.
