title: Effects of lactose as an inducer on expression of Helicobacter pylori rUreB and rHpaA, and Escherichia coli rLTKA63 and rLTB.
abstract: OBJECTIVE
  To demonstrate the effect of lactose as an inducer on expression of the recombinant proteins encoded by Helicobacter pylori ureB and hpaA, and Escherichia coli LTB and LTKA63 genes and to determine the optimal expression parameters.
  
  
  METHODS
  By using SDS-PAGE and BIO-RAD gel image analysis system, the outputs of the target recombinant proteins expressed by pET32a-ureB-E.coliBL21, pET32a-hpaA-E.coliBL21, pET32a-LTKA63-E.coliBL21 and pET32a-LTB-E.coliBL21 were measured when using lactose as inducer at different dosages, original bacterial concentrations, various inducing temperatures and times. The results of the target protein expression induced by lactose were compared to those by isopropyl-beta-D-thiogalactoside (IPTG). The proteins were expressed in E.coli.
  
  
  RESULTS
  Lactose showed higher efficiency of inducing the expression of rHpaA, rUreB, rLTB and rLTKA63 than IPTG. The expression outputs of the target recombinant proteins induced at 37 degrees were remarkably higher than those at 28 degrees. Other optimal expression parameters for the original bacterial concentrations, dosages of lactose and inducing time were 0.8, 50 g/L and 4 h for rHpaA; 0.8, 100 g/L and 4 h for rLTKA63; 1.2, 100 g/L and 5 h for both rUreB and rLTB, respectively.
  
  
  CONCLUSIONS
  Lactose, a sugar with non-toxicity and low cost, is able to induce the recombinant genes to express the target proteins with higher efficiency than IPTG. The results in this study establish a beneficial foundation for industrial production of H pylori genetic engineering vaccine.
authors.affiliation: Department of Medical Microbiology and Parasitology, College of Medical Science, Zhejiang University, 353 Yan An Road, Hangzhou 310031, Zhejiang Province, China. yanchen@mail.hz.zj.cn
authors.forename: Jie
authors.initials: J
authors.lastname: Yan
authors.forename: Shou-Feng
authors.initials: SF
authors.lastname: Zhao
authors.forename: Ya-Fei
authors.initials: YF
authors.lastname: Mao
authors.forename: Yi-Hui
authors.initials: YH
authors.lastname: Luo
mesh_terms: D018829:Adhesins, Bacterial; D001428:Bacterial Vaccines / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects*; D016480:Helicobacter pylori / Q000235:genetics*; D006388:Hemagglutinins / Q000235:genetics*; D007785:Lactose / Q000494:pharmacology*; D011994:Recombinant Proteins / Q000235:genetics; D013696:Temperature; D014510:Urease / Q000235:genetics*
chemical_list: D018829:Adhesins, Bacterial; D001428:Bacterial Vaccines; D029968:Escherichia coli Proteins; D006388:Hemagglutinins; D011994:Recombinant Proteins; C490750:hpaA protein, E coli; C095977:adhesin A, Helicobacter; D014510:Urease; D007785:Lactose