报告题目：How Signal Is Transduced Across Biological Membranes in the Heavy Metal Sensing Two Component Systems
报 告 人：Aixin Yan ? School of Biological Sciences, The University of Hong Kong
报告摘要：Two component systems (TCS) are a class of signal sensing and responding system broadly distributed in bacteria. It is composed of a membrane associated sensor histidine kinase (HK) and a cognate cytoplasmic response regulator (RR). Upon sensing specific signals, the system is activated via a phosphorelay from the HK to the RR component, resulting in the activation of the RR transcription factor and corresponding gene expression changes. Several dozens of two component systems have been identified and they regulate gene expression of a broad range of cellular processes in bacteria, ranging from nutrient acquisition, waste extrusion, to motility, virulence, drug resistance etc. While the periplasmic signal sensing domain and the cytoplasmic kinase domain of several TCSs have been crystalized and their molecular mechanisms been elucidated, how signal is transduced through the membrane in the system remains poorly understood. This is largely due to the fact that no crystal structure of the transmembrane domain of TCSs has been resolved. In this study, we use the heavy metal sensing CusSR TCS as a paradigm to elucidate an “unlock of membrane constraint” model for the transmembrane signal transduction process in TCSs.