Cloning And Expressing Of Human Histidyl-tRNA Synthetase Gene

Polymyositis(PM) and dermatoyositis(DM) , devastating inflammatory muscle diseases, are associated with the myositis-specific anti-Jo-1 autoantibody, found in 25-40% of such patients.Anti-Jo-1 antibodies react with histidyl-tRNA synthetase. It is most common, and is clinically the most important,as a marker antibody for PM or DM,especially in those patients with interstitial lung disease.Hisityl-tRNA synthetase catalyzes the aminoacylation of tRNAHis in the initial step of protein biosynthesis.The involumen of histidyl-tRNA synthetase in autoimmune diseases is another feature of the enzyme.In studies ,it is reported that purified Jo-1 antigen can increase the detection rate of anti-Jo-1 antibody.But it is difficult to obtain a single component by biochemical extraction .Genetic engineering can help us to desolve this problem. After looking up mRNA sequence encoding histidyl-tRNA synthetase in GeneBank, we used RT-PCR technology to gain its full length DNA sequence.The vestor pTYBllwas used in the construction of expressing vestor.We transformed the Jo-1 gene into ER2566 and used this system to express fusion Jo-1 antigen.The enzyme was expressed successfully as a fusion protein in ER2566.The predicted MW for the Jo-1 gene product is in good agreement with the size of the fusion protein determined by SDS-PAGE.But the level of expressed target protein is not so high.Meanwhile,the expressed fusion protein can be identified by anti Jo-1 antibody in ELISA..