Tm0853 and Tm0468 form a novel two component system in thermotoga maritima

Abstract

Two component systems (TSC) are the major mechanism used for signal transduction principally in prokariotes but also in some eukaryotes such as plants, fungus and yeast. A typical TSC consists of two proteins: a sensor dimeric histidine kinase (HK) serving as a signal receptor and its cognate response regulator (RR) mediating specific gene expression or enzymatic reactions required for innumerable adaptative responses as it can be seen in the figure below. Each cognate pair of sensor/regulator works as a faithful system and they are often encoded by adjacent ORFs or within the same operon. However, some two component genes are “orphans” with no functional cognate pair encoded nearby. Two-component proteins are well characterized structurally and functionally due to the conservation of their catalytic domains, however little is known about their complex formation. We have recently solved the structure of the cytoplasmic portion of the histidine kinase TM0853, therefore we present here the studies of the complex formation with its cognate RR.