The proteins needed for indole induced biofilm formation and their functions in E. coli DH5α
Date Issued
2010
Date
2010
Author(s)
Weng, Yu-Ping
Abstract
ABSTRACT
By using the two-dimensional gel method, we already discovered that when E. coli O157 was exposed to bacitracin, the expression of tryptophanase gene was induced through the EvgS/EvgA two-component system. Tryptophanase then converted tryptophan to indole,which caused biofilm formation as well as a series of related protein expression.
In this study, we screened the E. coli DH5α transposon library mutants to find out which genes are crucial for indole induced biofilm formation. These results show that when yhiP, cyaA, trkA, phr, and fimE genes are disrupted by transposon, indole can not induce these mutant strains to form biofilm. By using complementary assays, we confirmed that these genes are truly necessary for Indole induced biofilm formation in E. coli DH5α. Besides, we also used the reporter gene analysis method to further confirm that indole can cause these genes expressions with the promoter activity of yhiP, cyaA increased up to 200%. Moreover, we also clarified the relationship between indole and expressions of some transcription factor genes upstream to these genes, as well as the influences of each kind of common antibiotic to the expressions of these genes. In addition, we also used other experiment material such as butanol to test if expressions of these genes also contribute to the resistence to the adverse circumstance when E. coli formed biofilm.
Besides, the expression of B0363 can be induced byindole in E.coli. B0363 is an analogous protein of IcaA of staphylococcus, which is secreted to outside of cell after transcription. I also expressed and purified this protein successfully and made sure it has catalytic activity.
Subjects
indole
biofilm
Type
thesis
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