The Functions Of A Putative S-layer Protein SLP Of Bacillus Anthracis

Bacillus anthracis is a spore-forming, rod-shaped, gram-positive bacterium. It is the causative agent of the disease anthrax of human and herbivores, including cutaneous, gastrointestinal and inhalational anthrax. Anthrax is one of the five supremacies zoonosis and is a great harm to stock farming and human's health. Besides, B.anthracis is used as a biological warfare agent and a terrorist weapon causing a serious threat. Because of anthrax's large influence of society, the relative research is always the hot point of life science.Up to date little was known about relationship between B. anthracis'virulence genes and their pathogenesis. Thus, many researchers were focused on the study of ascertaining the function of those virulence factors and finding out unknown virulence substances.The slp gene was deleted through homologous recombination. Growth of the mutant and wild strain at 37℃were measured respectively, and some biochemical events of them were comparatively investigated. It had been found that the growth of the mutant was not different from the wild obviously. The biochemical feature of the wild strain and the mutant is similar. The electroporation condition of B. anthracis : electroporation container, 0.1 cm; voltage, 0.6 kv; resistance, 500 ?; capacitance, 25μF. The method of screening the mutant was established successfully.In additon to the experiments that were mentioned above, cell culturing (in vitro) and animal tests (in vivo) were also warranted to evaluate the functions of the slp gene. In this study, the cell model and mice experiments showed that the virulence of the mutant strain was more inferior to the wild strain.Moreover, two-dimensional electrophoresis was used to identify the differential expression of the mutant and the wild-type strain at various growth phases. 54 spots were processed and 28 spots were identified. It had been found that the mutant was different from the wild-type strain in the metabolism of B. anthracis. S-layer proteins(EA1) were up-regulated.In conclusion, the slp gene had little effects on the metabolism of Bacillus anthracis, but it can remarkably reduce the virulence of the B.anthracis.