Periplasmic expression of TNF related apoptosis inducing ligand [TRAIL] in E.coli

Tumor necrosis factor-related apoptosis-inducing ligand [TRAIL], a member of TNF family, is an interesting ligand which selectively induces apoptosis in tumor cells and, therefore, it has been developed for cancer therapy. This ligand has been produced by various hosts such as E.coli. However, protein expression in E.coli cytoplasm leads to problems such as incorrect folding, reduction in biological activity, inclusion body formation, and sophisticated downstream. The aim of this study is to develop an expression system for the production of recombinant TRAIL secreted to the E.coli periplasm instead of cytoplasm. By using Overlapping Extension PCR, an OmpA signal sequence was fused to TRAIL cDNA and OmpA-TRAIL fragment was then cloned in pET-22b plasmid. This construct was confirmed by PCR and DNA sequencing. Promoter was induced in E.coli BL21 [DE3] and periplasmic expressed proteins were released using osmotic shock procedure. SDS-PAGE analysis showed that about 37% of recombinant TRAIL was transferred into the periplasm and its identity was confirmed by western blot analysis. Finally, the cytotoxic activity of TRAIL against HeLa cell line was confirmed by using MTT assay. The results demonstrate that our expression system may be useful for the production of TRAIL in the periplasmic space

Characterization of an Extracytoplasmic Chaperone Spy in Protecting Salmonella against Reactive Oxygen/Nitrogen Species

Antimicrobial actions of reactive oxygen/nitrogen species (ROS/RNS) derived from products of NADPH oxidase and inducible nitric oxide (NO) synthase in host phagocytes inactivate various bacterial macromolecules. To cope with these cytotoxic radicals, pathogenic bacteria have evolved to conserve systems necessary for detoxifying ROS/RNS and repairing damages caused by their actions. In response to these stresses, bacteria also induce expression of molecular chaperones to aid in ameliorating protein misfolding. In this study, we explored the function of a newly identified chaperone Spy, that is localized exclusively in the periplasm when bacteria exposed to conditions causing spheroplast formation, in the resistance of Salmonella Typhimurium to ROS/RNS. A spy deletion mutant was constructed in S. Typhimurium by a PCR-mediated method of one-step gene inactivation with lambda Red recombinase, and subjected to ROS/RNS stresses. The spy mutant Salmonella showed a modest decrease in growth rate in NO-producing cultures, and no detectable difference of growth rate in H2O2 containing cultures, compared with that of wild type Salmonella. Quantitative RT-PCR analysis showed that spy mRNA levels were similar regardless of both stresses, but were increased considerably in Salmonella mutants lacking the flavohemoglobin Hmp, which are incapable of NO detoxification, and lacking an alternative sigma factor RpoS, conferring hypersusceptibility to H2O2. Results demonstrate that Spy expression can be induced under extreme conditions of both stresses, and suggest that the protein may have supportive roles in maintaining proteostasis in the periplasm where various chaperones may act in concert with Spy, thereby protecting bacteria against toxicities of ROS/RNS.

Periplasmic expression of Bacillus thermocatenulatus lipase in Escherichia coli in presence of different signal sequences

Efforts to express lipase in the periplasmic space of Escherichia coli have so far been unsuccessful and most of the expressed recombinant lipases accumulate in the insoluble cell fraction. To evaluate the role of native and heterologous signal peptides in translocation of the lipase across the inner membrane of E. coli, the lipase gene [btl2] was cloned downstream of the native Bacillus signal peptide and also in fusion with the pelB, ansB and ansB/asp signal peptides. For this purpose, four recombinant expression vectors [pYRKP.P, pYRKP.N, pYRKP. A and pYRKP.AA] were constructed and expressed in E. coli. Osmotic shock analysis showed that recombinant lipase was overexpressed as inclusion bodies in E. coli. The lipase inclusion bodies were subsequently solublized, refolded and purified using single column ion-exchange chromatography. To evaluate localization of lipase in the cell, the purified lipases were subjected to capillary isoelectric focusing and tandem mass spectrometry. Results showed that all signal peptides were able to direct the lipase from the cytoplasm into the periplasmic space of E. coli, because the periplasmic space of E. coli is not suitable for lipase folding, the translocated lipase aggregates in this space as inclusion bodies

Proteomic Analysis of Thiol-active Proteins of Helicobacter pylori 26695

Helicobacter pylori are a capnophilic bacterium, which colonize gastric mucosa and are resistant to acidic and oxidative damage. Thiol-active proteins subserve redox functions in tolerating oxidative stress and environmental toxicants, such as hydrogen peroxide and hypochlorous acid. We analyzed disulfide-containing proteins of H. pylori strain 26695. Active disulfide-containing proteins were separated by thiol-affinity chromatography, displayed with two-dimensional electrophoresis (2-DE), and identified by MALDI-TOF-MS. Thirty-five putative disulfide proteins, including AhpC (HP1563), GroEL (HP0011), and FrdB (HP0191), were identified in this study. In addition, 4 disulfide proteins of HypB, FusA, TufB, and AhpC showed enhanced intensities in the periplasmic space when compared with the pellet, suggesting that these proteins might play roles in the first redox system against environmental oxidative stresses. Disulfide-containing proteins identified in this study will provide the standard landscape for constructing the proteome components responsible for redox regulation of H. pylori.

Human tissue plasminogen activator expression in Escherichia coli using cytoplasmic and periplasmic cumulative power

Tissue plasminogen activator [tPA] is a serine protease, which is composed of five distinct structural domains with 17 disulfide bonds, representing a model of high-disulfide proteins in human body. One of the most important limitations for high yield heterologous protein production in Escherichia coli [E. coli] is the expression of complex proteins with multiple disulfide bridges. In this study the combination of two distinct strategies, manipulated cytoplasm and native periplasm, was applied to produce the functional full length tPA enzyme in E. coli. Using a PelB signal peptide sequence at 5' site of tPA gene, the expression cassette was prepared and subsequently was transformed into a strain with manipulated oxidizing cytoplasm. Then the induction was made to express the protein of interest. The SDS-PAGE analysis and gelatin hydrolysis confirmed the successful expression of functional tPA. The results of this study showed that complex proteins can be produced in E. coli using the cumulative power of both cytoplasm and periplasm

Production of the Recombinant Single Chain Anti-B Cell Lymphoma Antibody and Evaluation of Immunoreactivity / 핵의학분자영상

PURPOSE: Recombinant ScFv lym-1 was produced, using pET vector system for large scale production. METHODS: ScFv lym-1 gene inserted pET-22b (+) vector, was expressed in E.coli BL-21 strain. ScFv lym-1 antibody extracted from periplasm, was purified with His-Taq column. To evaluated immunoreactivity with Raji cell, ScFv lym-1 was labeled with I-125 and I-125 ScFv lym-1 was purified with desalting column. Raji cell was injected into the C57BR/cdJ SCID mice. Gamma camera imaging were taken time point at 1, 8, 24, and 48 hr with 8 mm pinhole collimator. RESULTS: An active scFv lym-1 could be produced in E.coli with soluble from using pET vector system. Immunoreactivity and affinity constant of IgG lym-1 were 54% and 1.83 x 10(9) M(-1), respectively, and those of scFv lym-1 were 53.7% and 1.46 x 10(9) M(-1), respectively. Biodistribution of I-125 scFv lym-1 antibody showed faster clearance in blood, spleen, kidney and than I-125 IgG lym-1 antibody. Gamma camera image of I-125 scFv lym-1 antibody showed faster clearance and tumor targeting liver than I-125 IgG lym-1 antibody. CONCLUSIONS: In vitro properties of scFv lym-1 were similar to those of IgG lym-1. ScFv lym-1 showed faster blood clearance than IgG lym-1. These results suggest that scFv lym-1 antibody can be useful for tumor imaging agent.

Spontaneous Kanamycin-resistant Escherichia coli mutant with altered periplasmic oligopeptide permease protein (OPPA) and impermeability to aminoglycosides

A spontaneous kanamycin-resistant Escherichia coli mutant, showing cross resitance to five other aminoglycosides and absence of the OppA protein was isolated. [3H]- dihydrostreptomycin uptake is reduced in this mutant, implying that the oligopeptide transport system in involved in accumulation of aminoglucosides, although apparently not related with aminoglycoside permeability alteration due to bacterial adaptation to osmotic changes.

Expression, Characterization and Chain Shuffling of an Anti-HBsAg Phage Antibody

In our previous report an anti-HBsAg human monoclonal antibody was generated using antibody phage display library technique. Using pComb3 filamentous phagemid vector, Fab molecule was expressed in fusion form to a phage coat protein in the periplasm of E. coli. A clone of HBsAg binder was selected after panning and designated as B7. In order to select the clones with higher affinity and to examine which chain contributes most to the affinity of B7, the light and heavy chain of B7 was sequentially deleted and replaced with new library. HBsAg-binders were selected and tested by EIA (enzyme immunoassay). It was revealed that the affinity of B7 depends only on the heavy chain of Fd. B7 Fd was constructed without light chain and specificity and affinity was further confirmed by western blot analysis. This human monoclonal Fd antibody was found to react with d antigenic determinant of HBsAg as the original clone did. The nucleotide sequence analysis revealed that VH of B7 could be classified into Kabat's subgroup II and human IgG heavy chain family IV. The CH1 of B7 was IgG1.

Production of Mouse Single Chain Fv Antibody to Surface Protein of Hepatitis B virus using Antibody Phage Display Library

In this study, we are to produce the single chain variable fragment (scFv) antibodies against surface protein of hepatitis B virus (HBV) using antibody phage display technique. Balb/c mice were immunized with preS1 and cDNAs of heavy and light chains of splenic B cells from immunized mice were prepared using RT-PCR. Two cDNAs were linked with (64S) linker DNA under recombination PCR to produce single chain Fv DNA. After digestion of scFv DNA with Sp 1 and Not 1, the digested DNA was ligated into pCANTAB 5E and electroporated into E. coli XL1-Blue to prepare scFv-library. The size of library was 1 * 10' pfu/ml. Phage antibodies (phabs) against preS1 were rescued with M13K07 helper phages, and preS1-binders were selected through 3 times of panning using 96 well microtitre plates. Phage antibody clones were assayed directly for the ability to bind preS1 by ELISA. And then 7 phage antibody clones had high ELISA signals against preS1. Phabs from preS1-specific pMsc-17 had the strongest ELISA signal to preS1. Phabs from pMsc-17 were used for Western blot to preS1 and the results revealed that it was specific to preS1. To prepare the soluble scFv antibody, phabs from pMsc-17 were transfected into non-suppressor E. coli HB2151, and grown under 1 mM IPTG. Soluble scFv antibody was mainly accumulated in the periplasmic space, but small amount of antibody was secreted into culture media.

Electron microscopic observation of Chlamydia pneumoniae / 대한임상병리학회지

BACKGROUND: Chlamydia pneumoniae causes pneumonia and upper respiratory tract infection and has been recently reported to be associated with coronary atherosclerosis. The difference between C. pneumoniae and other Chlamydia spp. has been demonstrated by serologic study, DNA analysis and ultrastructural observation. However, studies concerning the developmental cycle of C. pneumoniae are relatively short. This study was conducted to investigate the morphological changes and developmental characteristics of C pneumoniae in the HeLa cell. METHODS: To observe the intracellular inclusion of C. pneumoniae, the cultured HeLa cell monolayer was stained with Jones' iodine and Giemsa. The ultrastructures were examined with an electron microscope at 6, 24, 48, 72 and 96 hr after inoculation of elementary bodies. RESULTS: The C. pneumoniae organisms which formed intracytoplasmic inclusion bodies in HeLa cells were negative on iodine stain. In Giemsa-stained preparation, the inclusion bodies of variable sizes with a bluish purple color were identified in the cytoplasm of infected HeLa cells. After 6 hrs of infection, the elementary bodies with electron-dense spicule shaped substance of C. pneumoniae were enclosed by the HeLa cell membrane and were taken the host cell by endocytosis. After 24 hrs of infection, the electron-dense material in the elementary bodies were disappearing and the elementary bodies were transforming into reticulate bodies. After 48 hrs of infection, the reticulate bodies of C. pneumoniae were seen dividing by binary fission. Small electron-dense round bodies(miniature bodies) appeared near completion of division. After 72 hrs of infection. about half of the reticulate bodies were transformed into elementary bodies. Newly formed elementary bodies had a pear-shaped structure and large periplasmic space. After 96 hrs of infection. mature elementary bodies with condensed electron-dense material and a rigid outer membrane were observed. Miniature bodies were located in the cytoplasm of the elementary bodies. CONCLUSIONS: These unique morphological changes in HeLa cell culture show the developmental characteristics of C. pneumoniae.