Regulation of Cell Division, Biofilm Formation, and Virulence by FlhC in Escherichia coli O157:H7 Grown on Meat

Abstract

To understand the continuous problems that Escherichia coli O157:H7 causes as food pathogen, this study assessed global gene regulation in bacteria growing on meat. Since FlhD/FlhC of E. coli K-12 laboratory strains was previously established as a major control point in transducing signals from the environment to several cellular processes, this study compared the expression pattern of an E. coli O157:H7 parent strain to that of its isogenic flhC mutant. This was done with bacteria that had been grown on meat. Microarray experiments revealed 287 putative targets of FlhC. Real-time PCR was performed as an alternative estimate of transcription and confirmed microarray data for 13 out of 15 genes tested (87%). The confirmed genes are representative of cellular functions, such as central metabolism, cell division, biofilm formation, and pathogenicity. An additional 13 genes from the same cellular functions that had not been hypothesized as being regulated by FlhC by the microarray experiment were tested with real-time PCR and also exhibited higher expression levels in the flhC mutant than in the parent strain. Physiological experiments were performed and confirmed that FlhC reduced the cell division rate, the amount of biofilm biomass, and pathogenicity in a chicken embryo lethality model. Altogether, this study provides valuable insight into the complex regulatory network of the pathogen that enables its survival under various environmental conditions. This information may be used to develop strategies that could be used to reduce the number of cells or pathogenicity of E. coli O157:H7 on meat by interfering with the signal transduction pathways.

Flagellum Density Regulates Proteus mirabilis Swarmer Cell Motility in Viscous Environments

“…FlhD and FlhC form a heteromeric complex (36) that activates class II flagella genes, including the alternative sigma factor 28 , and leads to expression of class III flagellum genes (37)(38)(39). FlhD 4 C 2 also regulates the expression of genes that are not related to flagellum biogenesis, including cell division and aspects of metabolism (29,(40)(41)(42)(43)(44)(45).…”

Differential susceptibility of airway and ocular surface cell lines to FlhDC-mediated virulence factors PhlA and ShlA from Serratia marcescens

“…In a variety of bacteria, FlhDC has been shown to regulate a number of factors that probably play a role in pathogenesis. For example, FlhD and FhlC were reported to mediate biofilm and pellicle formation [6, 7], and expression of the phospholipase [8, 9], lipase, protease and haemolysin genes [1, 10]. Together, these and other studies support the suggestion that FlhDC is important in a broad range of gram-negative bacteria for control of motility and virulence determinants.…”

“…In a variety of bacteria, FlhDC has been shown to regulate a number of factors that probably play a role in pathogenesis. For example, FlhD and FhlC were reported to mediate biofilm and pellicle formation [6,7], and expression of the phospholipase [8,9], lipase, protease and haemolysin genes [1,10].…”

Acetate metabolism andEscherichia colibiofilm: new approaches to an old problem

“…It also impacts colonization of the mouse intestine (Horne et al ., ). In E. coli O157 : H7, FlhC inhibits cell division simultaneously with biofilm and the synthesis of LEE genes when bacteria grow on meat (Sule et al ., ).…”

“…It also impacts colonization of the mouse intestine (Horne et al, 2009). In E. coli O157 : H7, FlhC inhibits cell division simultaneously with biofilm and the synthesis of LEE genes when bacteria grow on meat (Sule et al, 2011). After the discovery of the impact of the acetate-OmpR-FlhD/FlhC pathway on the cell division rate, a partial network of regulation was summarized that centered on FlhD/FlhC, included numerous 2CSTS, and regulated all the biofilm-associated cell surface organelles (Pr€ uß et al, 2006).…”