Study on the methods for expression of the lpp20 gene of helicobacter pylori in escherichia coli TB1

Objective: To investigate the factors influencing expression level of the lpp20 gene of helicobacter pylori(Hp)in escherichia coli TB1 and the conditions under which the gene can be expressed most efficiently in order to construct a basis for purification and production of the antigen as an expected vaccine.Methods: The lpp20 gene of Hp was amplified from Hp chromosomal DNA by PCR techniques. The PCR product was inserted into the expression vector pMAL c2X. The recombinant vector was introduced into E. coli TB1, where the lpp20 gene was expressed at a variety of temperature, density of IPTG, and induction time. The expression products were analyzed using the SDS PAGE method.Results: During the induction time from 1?h to 4?h, the expression level kept changing markedly, while no remarkable change was found from 4?h to 8?h.No prominent difference had been found in expression of lpp20 gene using IPTG of 0.1～4.0 mmol/L. Using IPTG with a density of less than 0.2 mmol/L or more than?3.2?mmol/L,?expression level could? be? decreased? markedly; No?significant?difference hadbeen observed when the induction temperature was changed between 30℃～40℃ ;Under reasonable conditions for induction ,amount of the recombinant gene expression products could reach as high as 34% total proteins of the host.Conclusion :The recombinant vector constructed with pMAL-c2X and lpp20 gene could be expressed at a high level by adjustment of the induction conditions ,namely temper ature ,IPTG and induction time .