Display of heterologous proteins on the surface of E. coli by Red recombineering / 中华微生物学和免疫学杂志

Objective To display of heterologous proteins on the surface of E. coli . Methods The 1653 bp luciferase report gene was knocked in Ipp and ompA genes of chromosome by Red recombine system and selection-counter selection kan/sacB. Results The quantitative analysis results of exogenous lu-ciferase expression displayed that it could be expressed as fusion with the outer membrane proteins on the cell surface. The fusion protein of foreign protein and outer membrane protein Lpp-OmpA-Luc could be high-effi-ciently displayed on cell surface. Conclusion The stable expression of exogenous gene on the surface of E. coli had no effect on the bacterial growth and propagation.

Heterologous genes expression on Escherichia coli chromosome lac operon using Red recombination / 生物工程学报

To achieve efficient and stable expression of heterologous exogenetic protein or antigen in E. coli chromosome, the luciferase report gene was knocked in lacZ site of chromosome lac operon by using Red recombination system and selection-counterselection kan/sacB technology. The quantitative analysis of exogenous gene expression indicated that the target gene could be efficiently expressed at lacZ site of lac operon. The results confirmed the efficient screening and stable expression of heterologous protein or antigen on chromosome by using the recombinant engineering technique. This study demonstrated that the chromosome could be used as a vector for heterologous protein or antigen and the stable expression of exogenous gene on E. coli chromosome had no side effect on the bacterial growth and propagation.

Molecular Cloning and Characterization of a Putative Promoter Region of mPC-1 Gene Homologous to hPC-1 / 中国生物化学与分子生物学报

To identify the regulatory region that are responsible for the expression of mPC-1, we have isolated and characterized the mPC-1 gene promoter. Sequence analysis of the mPC-1 5' -flanking region and a series of truncated constructs were performed, which were transiently transfected into the prostate cancer cell lines and non-prostate cancer cell lines and analyzed through Dual-luciferase reporter assay system. The relative activity of mPC-1 gene promoter was by far higher than pGL3-control containing SV40 promoter and enhancer and p61-PSA containing hPSA 6 kb promoter in AR (androgen receptor, AR ) -positive prostate cancer cell lines. The region from 599 bp to 449 bp of mPC-1 promoter might contain a negative regulatory element. The expression of mPC-1 1.1 kb fragment is mainly restricted into prostate cancer cell lines. The relative activity of mPC-1 1.1 kb 5'-flanking region was regulated by androgen. The results demonstrated that the 1.1 kb fragment of mPC-1 5' -flanking region was relatively strong and prostate cancer cell specific promoter region.The 1.1 kb promoter of mPC-1 gene might be well suited to prostate cancer gene therapy if the promoter was properly modified.

Cloning and Expression of Various Deletants of Gsalpha Gene in Escherichia Coli / 中国实验血液学杂志

Gsalpha gene mutation has been discovered in some human tumors. In our previous studies, three novel deletants of Gsalpha gene, Gsalpha L-1(500 bp), Gsalpha L-2(300 bp), and Gsalpha L-3(200 bp), and wild type Gsalpha-4(1 200 bp) were found in human leukemia cell lines and detected in leukemic cells from patients with acute leukemia. To investigate the construction, function and biological significance of the deletants, the plasmids of Gsalpha L-1, Gsalpha L-2 and wild Gsalpha-4 were transformed into E. coli DH5, amplified by PCR, and cloned in expression vector pET22b(+), and then transformed into E. coli, respectively. As a result, higher levels of expression of three recombinants were obtained in form of inclusion bodies. The results suggested that these Gsalpha isoforms have an open reading frame of gene and can be expressed in vitro. The data lay a foundation to study the relation of Gsalpha gene to leukemogenesis.

Construction of the Antibody Library and Selection of the Antibodies Specifically Binding to the Prostate Carcinoma Cells / 中国肿瘤生物治疗杂志

Objective: To obtain phage-displayed ScFv library directly against prostate carcinoma cells, and select antibodies binding to prostate carcinoma cells specifically, so as to lay a foundation for developing diagnostic agents and clinical therapies of prostate carcinoma. Methods: Balb/c mice were immunized i. p . with purified membrane protein mixture of prostate carcinoma cells PC3, DU145. mRNA was isolated from the spleens of immunized mice, heavy and light chain genes ( VH and VL) of antibody were amplified separately by RT-PCR and assembled into ScFv gene with a specially constructed linker DNA. , the ScFv gene was ligated into the phagemid vector pCANTAB 5E and the ligated sample was transformed into competent E. coli TG1. The transformed cells were infected with M13K07 helper phage to yield recombinant phage. After five rounds of panning with PC3 cells, the positive clones were selected with the ELISA from the enriched phages. Results: A ScFv library of 3. 5 ? 106 was obtained and one phage-ScFv which can bind specifically PC3 cells was found. Conclusions: A prostate carcinoma specific antibody was identified , which paves a way for study of prostate carcinoma.