| Co-Investigator(Kenkyū-buntansha) |
SHIMIZU Tohru Department of Microbiology, Basic Medical Sciences, University of Tsukuba, Assis, 基礎医学系, 講師 (80235655)
OHTA Toshiko Department of Microbiology, Basic Medical Sciences, University of Tsukuba, Assoc, 基礎医学系, 助教授 (40233134)
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| Research Abstract |
The effects of stresses and stress proteins on the production of virulence factors from pathogenic bacteria, mainly gram positive cocci, staphylococcus aureus and rod, Clostridium perfringens, were studied on the basis of molecular biology aiming to find novel factors to control pathogenic bacteria.
staphylococcus aureus was found to produce heat shock proteins (HSP60 and HSP70) upon heat shock at 46C.The genes had rather similar sequences to those of E.coli and B.subtilis at structural region but had unique stem-and loop structure at the upstream region which was suspected to regulate the expression. The transcriptional factor that bind to the stem-and-loop was extensively searched and so far only one factor, plaC,has been suspected to be the regulator. Since the plaC seems to be common transcriptional factor, the regulatory mechanism in heat shock response must be different from those reported in E.coli or B.subtilis. Alkaline shock (pH 12) induced specific protein, ASP23, of which ge
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ne structure and physiological nature were elucidated. The roles of those stress induced proteins in the production of exotoxins were suggested to link to some other global regulatory system such as agr or two components regulatory system.
Clostridium perfringens produces multiple kinds of exotoxins like other gram positive organism. The production of those toxins was found to be globally regulated by two component system virR/virS.The virR positively regulated alpha-, rheta-, and kappa-toxin production, however, those genes had independent promoter structure and did not have consensus sequence that binds to VirR protein. By analyzing the virR/virS system, it was concluded that either the system modulates the effect via secondary regulatory genes that ate specific for each toxin structural gene or the VirR protein does not have a single consensus binding sequence. The secondary regulatory gene and the product were almost identified at present.
These observations will promote further study on the mechanism of production of bacterial virulence factors and encourage the invention of novel means to control bacterial pathogenesis in infectious diseases. Less
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