Biochemical characterization of a putative cytokinin-responsive His-kinase, CKI1, from Arabidopsis thaliana.
His-Asp phosphorelays are evolutionary-conserved powerful biological tactics for intracellular signal transduction. Such a phosphorelay is generally made up of "sensor histidine (His)-kinases", "response regulators", and "histidine-containing (HPt) phosphotransmitters". Results from recent intensive studies suggested that in the higher plant Arabidopsis thaliana, His-Asp phosphorelays may be widely used for propagating environmental stimuli, such as phytohormones (e.g., ethylene and cytokinin). In this study, we characterized, in vitro, the putative cytokinin-responsive CKI1 His-kinase, in terms of His-Asp phosphorelays. It was demonstrated for the first time that the receiver domain in this sensor exhibits a strong phosphohistidine phosphatase activity toward some Arabidopsis HPt phosphotransmitters (AHP1 and AHP2), suggesting the functional importance of the receiver domain for a resumed interaction of the sensor His-kinase with other His-Asp phosphorelay components.
Nakamura
A
A
Department of Biological Mechanisms and Functions, Graduate School of Bioagricultural Science, Nagoya University, Japan.
Kakimoto
T
T
Imamura
A
A
Suzuki
T
T
Ueguchi
C
C
Mizuno
T
T
D017360:Arabidopsis / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D029681:Arabidopsis Proteins; D003583:Cytokinins / Q000494:pharmacology; D004926:Escherichia coli / Q000235:genetics; D000071677:Histidine Kinase; D010766:Phosphorylation; D010770:Phosphotransferases; D010940:Plant Proteins / Q000378:metabolism; D011494:Protein Kinases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction
C117966:AHP1 protein, Arabidopsis; C117967:AHP2 protein, Arabidopsis; D029681:Arabidopsis Proteins; D003583:Cytokinins; D010940:Plant Proteins; D011994:Recombinant Proteins; D010770:Phosphotransferases; D011494:Protein Kinases; D000071677:Histidine Kinase; C101990:CKI1 protein, Arabidopsis