Prokaryotic expression and purification of Chlamydomonas reinhardtii intraflagellar transport protein 46(IFT46) and preparation of polyclonal antibody / 生物工程学报

IFT46 is one of the important components of intraflagellar transport complex B in Chlamydomonas reinhardtii, and plays important roles in the assembly, movement and perception of ciliary. To study its functional mechanism, a GST-tagged and an MBP-tagged prokaryotic expression plasmid, pGEX-2T-ift46 and pMAL-C2X-ift46 were constructed, respectively, by inserting ift46 into the pGEX-2T and pMAL-C2X vector, and then transformed into Escherichia coli BL21 (DE3) for protein expression. SDS-PAGE (15%) analysis results showed that the molecular weights of the fusion protein GST-IFT46 and MBP-IFT46 were 70 kDa and 86 kDa, respectively. We used the fusion protein GST-IFT46 purified by affinity adsorption purification (more than 95% purity) for immunity to New Zealand white rabbits. The 5th immune serum was collected and the antibody titer was determined to be 256 000 by ELISA. The antiserum was purified by Protein A affinity adsorption purification and immobilized MBP-IFT46 purification, and the specificity of polyclonal antibodies was evaluated by Western blotting and immunofluorescence. Results showed that the polyclonal antibody prepared could specifically and precisely bind IFT46 in C. reinhardtii, and IFT46 was mainly concentrated at basal body regions and few localized along the entire length of the flagellum as punctuated dots, which will make a foundation to further study the mechanism of IFT46 in cilia related diseases such as obesity, diabetes and polycystic kidney disease.

Cloning, expression and purification flagellar sheath adhesion of Helicobacter pylori in Escherichia coli host as a vaccination target

PURPOSE: Helicobacter pylori is a widely distributed gram-negative bacterium that infects the human stomach and duodenum. HpaA is a H. pylori-specific lipoprotein that has been shown to be an effective protective antigen against H. pylori infection. HpaA of H. pylori as a vaccine antigen is fully competent for stimulation of immune responses. The aim of this project is cloning, expression, and purification flagellar sheath adhesion of H. pylori in Escherichia coli host by fast protein liquid chromatography (FPLC) as a vaccination target. MATERIALS AND METHODS: The hpaA gene was inserted into pET28a (+) as cloning and expression vectors respectively. The recombinant plasmid (pET-hpaA) was subjected to sequencing other than polymerase chain reaction (PCR) and digestion analysis. Protein expression was induced by adding 1 mM isopropyl-beta-D-thiogalactoside to cultures of E. coli strain BL21 transformed with pET-hpaA. Protein expression assessed with sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis. Protein purification of flagellar sheath adhesion was by FPLC. RESULTS: The restriction endonuclease digestion, PCR amplification analysis showed that the hpaA gene of 730 bp was amplified from H. pylori DNA and sequencing analysis of the pET-hpaA confirmed the cloning accuracy and in frame insertion of hpaA fragment. SDS-PAGE analysis showed the expression of an approximately 29,000 Da protein. CONCLUSION: Sequencing results along with SDS-PAGE analysis confirms the expression of recombinant hpaA in the heterologous E. coli BL21. Conclusion A prokaryotic expression system for hpaA gene was successfully constructed. These results indicate that production of a specific recombinant protein is an alternative and potentially more expeditious strategy for development of H. pylori vaccine.

Structural analysis of flagellar axonemes from inner arm dynein knockdown strains of Trypanosoma brucei

Trypanosoma brucei is a protozoan flagellate that causes African sleeping sickness. Flagellar function in this organism is critical for life cycle progression and pathogenesis, however the regulation of flagellar motility is not well understood. The flagellar axoneme produces a complex beat through the precisely coordinated firing of many proteins, including multiple dynein motors. These motors are found in the inner arm and outer arm complexes. We are studying one of the inner arm dynein motors in the T. brucei flagellum: dynein-f. RNAi knockdown of genes for two components of dynein-f: DNAH10, the a heavy chain, and IC138, an intermediate chain, cause severe motility defects including immotility. To determine if motility defects result from structural disruption of the axoneme, we used two different flagellar preparations to carefully examine axoneme structure in these strains using transmission electron microscopy (TEM). Our analysis showed that inner arm dynein size, axoneme structural integrity and fixed central pair orientation are not significantly different in either knockdown culture when compared to control cultures. These results support the idea that immotility in knockdowns affecting DNAH10 or IC138 results from loss of dynein-f function rather than from obvious structural defects in the axoneme.

Actin-interacting and flagellar proteins in Leishmania spp: bioinformatics predictions to functional assignments in phagosome formation

Several motile processes are responsible for the movement of proteins into and within the flagellar membrane, but little is known about the process by which specific proteins (either actin-associated or not) are targeted to protozoan flagellar membranes. Actin is a major cytoskeleton protein, while polymerization and depolymerization of parasite actin and actin-interacting proteins (AIPs) during both processes of motility and host cell entry might be key events for successful infection. For a better understanding the eukaryotic flagellar dynamics, we have surveyed genomes, transcriptomes and proteomes of pathogenic Leishmania spp. to identify pertinent genes/proteins and to build in silico models to properly address their putative roles in trypanosomatid virulence. In a search for AIPs involved in flagellar activities, we applied computational biology and proteomic tools to infer from the biological meaning of coronins and Arp2/3, two important elements in phagosome formation after parasite phagocytosis by macrophages. Results presented here provide the first report of Leishmania coronin and Arp2/3 as flagellar proteins that also might be involved in phagosome formation through actin polymerization within the flagellar environment. This is an issue worthy of further in vitro examination that remains now as a direct, positive bioinformatics-derived inference to be presented.

Periodic variety in swarming motility of Proteus mirabilis / 第三军医大学学报

Objective To investigate the periodic variety at the germ form, quantity, flagellar expression and activity of breath enzyme etc during the swarming motility of Proteus mirabilis (PM). Methods The 2, 3, 5-tetraphenyltetrazolium chloride (TTC), as indictor of breath enzyme, was added to the culture medium. Electronic microscope was adopted to observe the germ form and flagellar. Quantity of PM was measured by turbidimetry. Results During the PM growth and migration at LB medium, the germ quantity reduced and form changed from short and small to long and thin, flagellar got more and breath enzyme turned into inactive. Conclusion At the LB medium, PM in growth process appeared varieties in length of germ body, flagellar quantity and germs density, etc. PM in solid medium appeared wave motility, resulting from many factors including the environment, the signal transduction in cells and the density of germ.

Progress on Swimming Mechanism of Flagellar Bacteria / 微生物学通报

Some types of bacteria swim through rotating their flagella. The swimming mechanism of bacteria during flagella bundling and tumble process is analyzed. The effects of body rotation and flagellum′s polymorphic transitions on bundling processes and the wall effect phenomenon are also discussed. Finally, based on dynamics similarity, a new microrobot module is put forward to further studying the flagella swimming phenomena. The research would be very helpful for constructing the bionic swimming robots under the low Reynolds number.

Abnormal flagellar production in O-antigen mutants of Citrobacter freundii / 第三军医大学学报

Objective To study the molecular mechanism of swarming motility in Citrobacter freundii.Methods Mini-Tn5 transposon was used to induce swarming mutants in Citrobacter freundii.The mutant genes were amplified by inverse-PCR and were then sequenced.Mutants were observed under light microscope and electron microscope to determine the characters of motility and bacterial shape.Results Seven swarming mutants were found to be three gene mutants(wzxB,waaW,waaL) involving LPS synthesis.Moreover,flagellar production of these mutants was abnormal,that is,only small portion of bacterial cells produced flagella normally.The majority of cells tended to aggregate and produced little flagella observed under electron microscope.Conclusion Absence of O-antigen affects the production of flagella and swarming motility of Citrobacter(freundii).