Structural basis of the signal transduction in the two-component system

Abstract

Two-component system (TCS) consists of two multi-domain proteins, a sensor histidine kinase (HK) and a response regulator (RR). In response to environmental change, the signal is transduced from HK to RR through phosphoryl transfer. At the first stage of structural biology of TCS, crystallographic and NMR analyses of domain blocks revealed the folds and the remarkable regions of sensor, dimerization and catalytic domains of HK and receiver and effecter domains of RR. As the second stage, the advanced researches of their multi-domain form and HK/RR complex showed the inter-domain and inter-molecular interactions and implied that the dynamic conformation changes are required in the signaling process. Thus, this chapter describes what these structural analyses of TCS proteins have contributed in understanding the cell signaling mechanism; signal input --> phosphoryl transfer --> signal output.