The Arabidopsis sensor His-kinase, AHk4, can respond to cytokinins.
His-to-Asp (His-->Asp) phosphorelay mechanisms are presumably involved in propagation of certain environmental stimuli, including phytohormones, in Arabidopsis thaliana. In addition to the previously characterized His-kinases, namely, the ETR1 family of ethylene receptors, CKI1 cytokinin-sensor, and ATHK1 osomo-sensor, this higher plant has three more His-kinases (named AHK2, AHK3, and AHK4). By employing the well-known His-->Asp phosphorelay systems in both the fission yeast and Escherichia coli, evidence is presented showing that the AHK4 His-kinase has an ability to serve as a cytokinin-responsive environmental sensor. Taking advantage of this AHK4-dependent His-->Asp phosphorelay system in E. coli, a phosphorelay interaction between the Arabidopsis His-kinase and histidine-containing phosphotransmitters (AHPs) was also demonstrated for the first time.
Suzuki
T
T
Laboratory of Molecular Microbiology, School of Agriculture, Nagoya University, Chikusa-ku, Nagoya, 464-8601 Japan.
Miwa
K
K
Ishikawa
K
K
Yamada
H
H
Aiba
H
H
Mizuno
T
T
D017360:Arabidopsis / Q000201:enzymology*; D029681:Arabidopsis Proteins; D003583:Cytokinins / Q000378:metabolism*; D004926:Escherichia coli / Q000378:metabolism; D000071677:Histidine Kinase; D011494:Protein Kinases / Q000378:metabolism*; D012568:Schizosaccharomyces / Q000378:metabolism
D029681:Arabidopsis Proteins; D003583:Cytokinins; D011494:Protein Kinases; D000071677:Histidine Kinase; C000605492:AHK2 protein, Arabidopsis; C000605493:AHK3 protein, Arabidopsis