Cloning Of Full-length Gene For Tobacco Ethylene Receptor NTHK2 And Its Function Studying

The organism regulates its growth and development by sensing the variety of inside and outside factors. There is a kind of two-component signaling system in lots of signals sensing and transdusing. It plays significant roles in the organism growth and development progress. In recent years it is found that this signal transduction mechanism not only lies in prokaryote but also in eukaryote such as yeast, slime mold and plant. It involves in the regulating to infiltrate stress and hormone signal transduction. Recently it is found that there are five relative genes ETR1, ERS1, ETR2, EIN4 and ERS2 with ethylene signal transduction. They all have homologue sequences with bacteria or slime mold two- component's histidine kinase sensor. ETR1 can combine with ethylene and have kinase activity, so it may be a ethylene receptor. In tobacco four genes have been cloned, NTETR1,NTERS1,NTHK1 and NTHK2.Screen tobacco cDNA library using two-component gene NTHK1 as probe and get its homologue gene NTHK2.The full-length of a two-component gene histidine kinase homologue NTHK2(Nicotiana tabacum histidine kinase) was isolated from tobacco. NTHK2 gene has 3216bp, with 509bp of 5'-non-coding region and 427bp of 3'-non-coding region, and encodes an ethylene-receptor homolog of 760 amino acids. Sequence analysis revealed that NTHK2 shared highhomology with LeETR5 from tomato and encoded an ethylene receptor homolog. The predicted NTHK2 protein had a putative four transmembrane domains, a putative histidine kinase domain and a receiver domain. But there are not conserve histidine residue, N, G1, F, G2 box, the histidine kinase activity of NTHK2 is remained to be identified.It is found that NTHK2 is low copy in tobacco by Southern blot.NTHK2 is induced by ethylene,wounding,drought,cold,CaCl2 and is inhibited by ABA, hot. NaCl and other factors do not effect to it. So NTHK2 involves in some stress responses.In transgenic Arabidopsis leaf is bigger and florescence delay than wild type. And the exogenous gene was identified to be inserted into the genome of Arabidopsis via PCR and Southern blot.NTHK2 expression examines and transgenic Arabidopsis abiotic treat is to be going. Identified the downstream genes of NTHK1 and obtained about 30 interaction genes with NTHK1 likely by screening tobacco stress library via yeast two-hybrid. These genes relate with growth and development, signal transduction, oxygen stress, protein synthesis and other unknown signal transduction approaches.