Title: Regulation of the csgD promoter by global regulators HN-S, IHF, and RpoS in E. coli O157:H7 isolates Authors
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: March 6, 2012
Publication Date: July 22, 2012
Citation: Chen, C., Uhlich, G.A. 2012. Regulation of the csgD promoter by global regulators HN-S, IHF, and RpoS in E. coli O157:H7 isolates [abstract]. Poster p-3-121. Technical Abstract: Introduction: Curli production is essential for the biofilm formation in E. coli and Salmonella. The control of expression of CsgD, the key regulator of the curli operon, is very complex, and has been shown to be regulated by several global regulators and is influenced by various growth and stress conditions such as stationary phase, nutrient deprivation, temperature, and osmotic perturbation. Purpose: We sought to understand the interplay between various global regulators and growth phase on the regulation of csgD promoter, and to find the promoter region that is required for csgD expression in the E. coli STEC strains. Methods: Various lengths of the promoter region between csgD and csgB from a wild-type E. coli O157:H7 EDL933 strain (ATCC43895) and a strong curli-producing isolate were used to generate the lacZ translational fusions on a plasmid. The plasmids were then introduced into different strains carrying deletion of the potential regulators of csgD, such as rpoS, himA, and hns. '-galactosidase assays were performed throughout growth phases and the expression patterns were compared. Results: We identified the minimal promoter length required for efficient csgD expression, as well as different regions that interact with the global regulators. Particularly, we found a ca. 600-bp csgD promoter was strongly affected in various mutants. The expression of this promoter was dramatically increased in all growth stages in the rpoS mutant compared to those of the wild-type. On the other hand, the hns and himA deletions only affected the expression of this csgD promoter in the late log to stationary phase. Significance: By understanding the expression control of csgD gene, we gain insight into the regulation of curli production and biofilm formation. These csgD promoter fusions can be used as tools for evaluation of the biofilm-forming potential of the STEC isolates.