Evidence for serine/threonine and histidine kinase activity in the tobacco ethylene receptor protein NTHK2.
Ethylene plays important roles in plant growth, development, and stress responses. Two ethylene receptors, ETR1 from Arabidopsis and NTHK1 from tobacco (Nicotiana tabacum), have been found to have His kinase (HK) activity and Ser/Thr kinase activity, respectively, although both show similarity to bacterial two-component HK. Here, we report the characterization of another ethylene receptor homolog gene, NTHK2, from tobacco. This gene also encodes a HK-like protein and is induced by dehydration and CaCl(2) but not significantly affected by NaCl and abscisic acid treatments. The biochemical properties of the yeast (Schizosaccharomyces pombe)-expressed NTHK2 domains were further characterized. We found that NTHK2 possessed Ser/Thr kinase activity in the presence of Mn(2+) and had HK activity in the presence of Ca(2+). Several lines of evidence supported this conclusion, including hydrolytic stability, phosphoamino acid analysis, mutation, deletion, and substrate analysis. These properties have implications in elucidation of the complexity of the ethylene signal transduction pathway and understanding of ethylene functions in plants.
National Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.
Zhi-Gang
ZG
Zhang
Hua-Lin
HL
Zhou
Tao
T
Chen
Yan
Y
Gong
Wan-Hong
WH
Cao
Yu-Jun
YJ
Wang
Jin-Song
JS
Zhang
Shou-Yi
SY
Chen
D000040:Abscisic Acid / Q000494:pharmacology; D000595:Amino Acid Sequence; D002122:Calcium Chloride / Q000494:pharmacology; D003681:Dehydration; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D000071677:Histidine Kinase; D008345:Manganese / Q000494:pharmacology; D008969:Molecular Sequence Data; D010937:Plant Growth Regulators / Q000494:pharmacology; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011494:Protein Kinases / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D036226:Seedlings / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D014026:Nicotiana / Q000201:enzymology* / Q000378:metabolism
D010937:Plant Growth Regulators; D010940:Plant Proteins; D011956:Receptors, Cell Surface; C083750:ethylene receptors, plant; D008345:Manganese; D000040:Abscisic Acid; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases; D000071677:Histidine Kinase; D002122:Calcium Chloride