Plant Histidine Kinases: An Emerging Picture of Two-Component Signal Transduction in Hormone and Environmental Responses

Takeshi Urao¹, Kazuko Yamaguchi-Shinozaki¹, and Kazuo Shinozaki^2,*

¹Biological Resources Division, Japan International Research Center for Agricultural Science (JIRCAS), Ministry of Agriculture, Forestry and Fisheries, 1-1 Ohwashi, Tsukuba, Ibaraki 305-8686, Japan.
²Laboratory of Plant Molecular Biology, RIKEN Tsukuba Institute, 3-1-1 Koyadai, Tsukuba, Ibaraki 305-0074, Japan.

*Corresponding author: Telephone: +81-298-36-4359, fax: +81-298-36-9060, e-mail: sinozaki{at}rtc.riken.go.jp

Abstract: In the Arabidopsis thaliana genome, 11 genes encode bacterial-type two-component histidine kinases. Genetic and biochemical analyses indicate that five two-component histidine kinase-like proteins (ETR1, ETR2, EIN4, ERS1, and ERS2) function as ethylene receptors. A hybrid histidine kinase, CRE1 (also known as AHK4), acts as a cytokinin receptor, and a set of response regulators may be involved in cytokinin signal transduction. In addition to CRE1, histidine kinases CKI1 and CKI2 are likely to play important roles in cytokinin signaling. A database search of the entire Arabidopsis genome sequence has identified two additional homologs of CRE1. Arabidopsis seems to employ a hybrid histidine kinase, ATHK1, as an osmosensor. Plants widely use two-component systems in the detection of, and signal transduction by, the growth regulators ethylene and cytokinin, as well as in their responses to environmental stimuli.

Citation:
T. Urao, K. Yamaguchi-Shinozaki, K. Shinozaki, Plant Histidine Kinases: An Emerging Picture of Two-Component Signal Transduction in Hormone and Environmental Responses. Science's STKE (2001), http://stke.sciencemag.org/cgi/content/full/OC_sigtrans;2001/109/re18.

© 2001 American Association for the Advancement of Science