Prokaryotic Expression And Functional Characterization In Vitro Of Dehydrin Gene Dhn2from Camellia Sinensis

Dehydrin was firstly found in1980s,which is a kind of late embryogenesis abundant proteins.It belongs to the family of LEAD-Ⅱ and its molecular weight changing from9to200KD.In recent years, the research of dehydrin advanced rapidly, espcially their protecting function to the plants attracted more and more pepole’s attention. The dehydrin is abundant in glycin and lysine, because of that dehydrins are highly hydrophilic and can combine with cell membrane easily in order to prevent excessively water erosion.That is the reason why dehydrin can protect cells from the damage of drought.In addition, proteins can also been protected by dehydrins because of their double affinity structure of alpha helix serving seemly as molecular chaperone.Camellia sinensis is a kind of Perennial economic crops in subtropical area and vulnerable to cold. So how to enhance the tea plant’s ability of anti-cold has attracted more and more attention.The fragment of one dehydrin was screened form SSH library of tea induced by cold.After amplified by RACE kit and sequenced, the dehydrin was identified as SK2type and then named dhn2. The results of the studies are listed as follows:Firstly, the transcriptions of dhn2under the stresses of cold, dehydration and ABA were tested by the method of RT-PCR.The result showed that dhn2could be induced by cold, dehydration and ABA, in which the induced effect of cold and dehydration were very obvious.Hence,it could speculated that dhn2plays important role in resistance of cold and drought.Secondly, procaryotic expression vector of dhn2was constructed successfully.After induced by0.8mmol/L IPTG at30℃, a53KD combinant protein was obtained and was positive to antibody anti-dehydrin.So,the protein could be certified as dhn2recombinant protein.The purity of dhn2after purification is around90%.Finally, in vitro testing, the protective function of the dehydrin protein was very obvious, the residual enzyme activity of MDH and LDH still remained86%,62%respectively, after dehydration and freezing inactivation.Compared with BSA,dhn2had higher ability of anti-drought but lower ability of anti-freeze.