• Journal of Microbiology and Biotechnology
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• v.20 no.2
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• pp.301-310
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• 2010

Bacillus subtilis strains produce a broad spectrum of bioactive peptides. The lipopeptide surfactin belongs to one well-known class, which includes amphiphilic membrane-active biosurfactants and peptide antibiotics. Both the srfA promoter and the ComP-ComA signal transduction system are an important part of the factor that results in the production of surfactin. Bs-M49, obtained by means of low-energy ion implantation in wild-type Bs-916, produced significantly lower levels of surfactin, and had no obvious effects against R. solani. Occasionally, we found strain Bs-M49 decreased spore formation and the development of competence. Blast comparison of the sequences from Bs-916 and M49 indicate that there is no difference in the srfA operon promoter PsrfA, but there are differences in the coding sequence of the comA gene. These differences result in three missense mutations within the M49 ComA protein. RT-PCR analyses results showed that the expression levels of selected genes involved in competence and sporulation in both the wild-type Bs-916 and mutant M49 strains were significantly different. When we integrated the comA ORF into the chromosome of M49 at the amyE locus, M49 restored hemolytic activity and antifungal activity. Then, HPLC analyses results also showed the comA-complemented strain had a similar ability to produce surf actin with wild-type strain Bs-916. These data suggested that the mutation of three key amino acids in ComA greatly affected the biological activity of Bacillus subtilis. ComA protein 3D structure prediction and motif search prediction indicated that ComA has two obvious motifs common to response regulator proteins, which are the N-terminal response regulator receiver motif and the C-terminal helix-turn-helix motif. The three residues in the ComA N-terminal portion may be involved in phosphorylation activation mechanism. These structural prediction results implicate that three mutated residues in the ComA protein may play an important role in the formation of a salt-bridge to the phosphoryl group keeping active conformation to subsequent regulation of the expression of downstream genes.

• Journal of Life Science
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• v.11 no.2
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• pp.181-189
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• 2001

Cytokines are hormone-like proteins which mediate and regulast inflammatory and immune responses. Transforming growth factor -$\beta$1(TGF-$\beta$) plays an important role in the control of the immune response and wound healing, and in the development o various tissues and organs, Nitric oxide(NO) is major messenger molecule regulating immune function and blood vessel dilation and serving as a neurotransmitter in the brain and peripheral nervous system. Also, NO is to be a potent mutagen that cause mutation in the p53 tumor suppressor gene in early phases of human gastric carcinogenesis. The purpose of this study was to investigate the effect of Helicobacter phlori lystes, lipopolysaccharide (LPS), and Staphylococcus enterotoxin B(SEB) on production of TGF-$\beta$1 and NO by human fibroblasts. Primary cultured human fibroblasts were incubated with H. pylori lysates(Hp), LPs, SEB, Hp+LPS, Hp+SEB, Hp+LPS+SEB. Cultured supernatants that were collected at 24, 48 and 72 hr were assessed for TGF-$\beta$1 by enzyme-linked immunosorbent assay and NO production by quantification of nitrite ion. TGF-$\beta$1 production in fibroblasts exposed with Hp, LPS or SEB for 48 hrs was enhanced, but for 72 hrs inhibited. Its production by doble exposure such as Hp+LPS, Hp+SEB, Hp+LPS+SEB was lowered in comparison with single exposure of Hp in cases of 24 and 48 hrs incubation, but for 72 hrs decreased in Hp vaculoating toxin(+), increased in Hp vacuolating toxin(-). No production in fibroblasts increaed at all doses of LPS. But its production by exposure of SEB increased or decreased according to dose and incubation time. Also, NO production by Hp vacuolating toxin(+) increased at all doses, but its production by Hp vacuolating toxin(-) decreased. Its production by doble exposure such as Hp+LPS, Hp+SEB, Hp+LPS+SEB decreased in comparison with single exposure Hp Therefore, quantities pf TGB-$\beta$1 and NO released by human fibroblasts shows differences according to kinds of stimulants. Also, in care stimulated with same kinds of stimulants, its productions exhibit quantitative differences according to exposure times. These results suggest that the decreased of TGF-$\beta$1 in fibroblasts by mixed exposure with Hp producing vacuolating toxin and bacterial toxins such as LPS and SEB may effect negatively in healing of host tissue and increased of NO by infection oh H. pylori may related to the increased susceptibility for human gastric carcinogenesis.