Cloning And Functional Analysis Of Cyclin-dependent Protein Kinases,NtCDK8 From Nicotiana Tobacco

Any species in nature, are valuable, and plant is closely related to human life. Oxygen released by photosynthesis in algae had built the foundation for the evolution of life; Originated in Mesopotamia wheat, Mexico corn,and the Chinese rice in zhejiang province for thousands of years have been witness to and support the growth of human beings. Plant cell divisions and differentiation produce the complete plant. Therefore,efforts from micro aspect should be made to reasch the division and differentiation of plant cell, and change the traits of plant.CDK (cyclin dependent kinase) was found in the 1980s from yeast. and It plays an important role in the process of cell cycle regulation. However, the reasch of CDK is few in plant. This article analysis the CDK family of Nicotiana tobacum by bioinformatics method, and molecular biology experiments is taken to CDK. We get this data:1 CDK can be divided into A, B, C, D, E, F, G seven classes and the CDK-Like class, some conservative structure domain features similar. At present through multiple sequence alignment and phylogenetic analysis, is A kind of CDK gene has PSTAIRE conservative domain structure, class B CDK has PPTALRE conservative domain, the C class CDK is PITAIRE conservative domain structure, class E CDK is SPTAIRE conservative conservative domain structure, class G CDK PLTSLRE conservative structure domain. At present through multiple sequence alignment and phylogenetic analysis, it is presumed that A kind of CDK gene has PSTAIRE conservative domain structure, class B CDK has PPTALRE conservative domain, the C class CDK is PITAIRE conservative domain structure, class E CDK is SPTAIRE conservative domain structure, class G CDK PLTSLRE conservative structure domain.2 In order to explore the biological function of cyclin-dependent protein kinases in Nicotiana tobacco, a cyclin-dependent protein kinases like gene, named NtCDK8, was identified by homology search. The application of RT-PCR revealed that the coding sequence of NtCDK8 was 1422 bp, encoding 473 amino acids. Bioinformatics analysis showed that NtCDK8 was highly homologous to the cyclin-dependent protein kinases genes of Solanum lycopersicum, Solanum tuberosum. The predicted protein of NtCDK8 has Serine/Threonine protein kinase domain, which is a typical feature of cyclin-dependent protein kinase. Through the prediction of protein structure, hydrophilicty, signal peptide and subcellular localization, it is presumed that NtCDK8 should be a hydrophilic proteins in the nucleus with function phosphorylating Serine/Threonine of downstream prctein, and promoting signals passing from outside into inside of cell. Expression pattern analysis showed the expression of CDK8 under drought, salt stress, low temperature have great change, it showed the expression of CDK8 is related with the signal of environment. Hormone treatment analysis showed that exogenous hormones such as auxin and abscisic acid isrelated with the expression of CDK8,too. Subcellular localization prediction, CDK8 is located in the nucleus.To further explain NtCDK8 biology function, the transgene experiment of NtCDK8 was carried out at the same time. The plant of over-expression of CDK8 have a stronger disease-resistent ability, leaf and cell is bigger.