Abstract
Two-component system, widely known as the mechanism to respond to the environmental stimuli, functions to transmit cytokinin signaling. It consists of sensory histidine kinase, histidine-phosphotransfer protein (HPt) and response regulator (RR) in order of the signaling transmission. A number of genes involved in the signaling cascade have been identified in Arabidopsis and maize, suggesting that fine structural discrimination between each component at the molecular level is essential for conducting accurate signal transduction. Especially, HPt, whose isoforms are fewer than those of RR, must integrate and branch off the signaling information. We have determined the crystal structures of two maize HPt isoforms, ZmHP1 and ZmHP2. Moreover, the structure of ZmHP3 has been built by homology modeling. We are planning to report the relationship between structural differences among three HPt isoforms in maize and their binding specificities with RR.
