Roles of ethylene receptor NTHK1 domains in plant growth, stress response and protein phosphorylation.
Ethylene receptors sense ethylene and regulate downstream signaling events. Tobacco ethylene receptor NTHK1, possessing Ser/Thr kinase activity, has been found to function in plant growth and salt-stress responses. NTHK1 contains transmembrane domains, a GAF domain, a kinase domain and a receiver domain. We examined roles of these domains in regulation of plant leaf growth, salt-stress responses and salt-responsive gene expressions using an overexpression approach. We found that the transgenic Arabidopsis plants harboring the transmembrane domain plus kinase domain exhibited large rosettes, had reduction in ethylene sensitivity, and showed enhanced salt sensitivity. The transgenic plants harboring the transmembrane domain plus GAF domain also showed larger rosettes. Truncations of NTHK1 affected salt-induced gene expressions. Transmembrane domain plus kinase domain promoted RD21A and VSP2 expression but decreased salt-induction of AtNAC2. The kinase domain itself promoted AtERF4 gene expression. The GAF domain itself enhanced Cor6.6 induction. Moreover, the NTHK1 functional kinase domain phosphorylated the HIS and ATP subdomains, and five putative phosphorylation sites were identified in these two subdomains. In addition, the salt-responsive element of the NTHK1 gene was in the transmembrane-coding region but not in the promoter region. These results indicate that NTHK1 domains or combination of them have specific functions in plant leaf growth, salt-stress response, gene expression and protein phosphorylation.
Zhou
Hua-Lin
HL
National Key Lab of Plant Genomic, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.
Cao
Wan-Hong
WH
Cao
Yang-Rong
YR
Liu
Jun
J
Hao
Yu-Jun
YJ
Zhang
Jin-Song
JS
Chen
Shou-Yi
SY
D000222:Adaptation, Physiological; D017360:Arabidopsis / Q000254:growth & development / Q000502:physiology; D001483:Base Sequence; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D010766:Phosphorylation; D018515:Plant Leaves / Q000254:growth & development; D010940:Plant Proteins / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic; D017434:Protein Structure, Tertiary; D011956:Receptors, Cell Surface / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D012965:Sodium Chloride / Q000494:pharmacology; D014026:Nicotiana / Q000235:genetics
D010940:Plant Proteins; D011956:Receptors, Cell Surface; C083750:ethylene receptors, plant; D012965:Sodium Chloride