Interacting Cra and KdpE Regulators Are Involved in the Expression of Multiple Virulence Factors in Enterohemorrhagic Escherichia coli

• Published in: Journal of Bacteriology Vol. 195; no. 11; pp. 2499 - 2508
• Main Authors: Njoroge, Jacqueline W, Gruber, Charley, Sperandio, Vanessa
• Format: Journal Article
• Language: English
• Published: United States American Society for Microbiology 01.06.2013
• Subjects: Bacterial Proteins - genetics; Bacterial Proteins - isolation & purification; Bacterial Proteins - metabolism; Bacteriology; Base Sequence; carbon; Carrier Proteins - genetics; Carrier Proteins - metabolism; DNA-binding proteins; Down-Regulation; E coli; enterohemorrhagic Escherichia coli; epithelial cells; Escherichia coli; Escherichia coli Infections - microbiology; Escherichia coli O157 - genetics; Escherichia coli O157 - growth & development; Escherichia coli O157 - metabolism; Escherichia coli Proteins - genetics; Escherichia coli Proteins - metabolism; Gene expression; Gene Expression Profiling; Gene Expression Regulation, Bacterial - genetics; genes; genomic islands; Homeostasis; Humans; loci; metabolism; Metabolites; Models, Genetic; Molecular Sequence Data; mutants; Mutation; Oligonucleotide Array Sequence Analysis; osmolarity; pathogenesis; pathogens; Phosphoproteins - genetics; Phosphoproteins - metabolism; Protein Interaction Mapping; Repressor Proteins - genetics; Repressor Proteins - isolation & purification; Repressor Proteins - metabolism; Sequence Deletion; Trans-Activators - genetics; Trans-Activators - metabolism; transcription (genetics); transcription factors; Transcriptome; Up-Regulation; Virology; Virulence; Virulence Factors - metabolism
• ISSN: 0021-9193; 1098-5530; 1067-8832
• DOI: 10.1128/JB.02252-12

The human pathogen enterohemorrhagic Escherichia coli (EHEC) O157:H7 codes for two interacting DNA binding proteins, Cra and KdpE, that coregulate expression of the locus of enterocyte effacement (LEE) genes in a metabolite-dependent manner. Cra is a transcription factor that uses fluctuations in the concentration of carbon metabolism intermediates to positively regulate virulence of EHEC. KdpE is a response regulator that activates the transcription of homeostasis genes in response to salt-induced osmolarity and virulence genes in response to changes in metabolite concentrations. Here, we probed the transcriptional profiles of the Δcra, ΔkdpE, and Δcra ΔkdpE mutant strains and show that Cra and KdpE share several targets besides the LEE, but both Cra and KdpE also have independent targets. Several genes within O-islands (genomic islands present in EHEC but absent from E. coli K-12), such as Z0639, Z0640, Z3388, Z4267, and espFu (encoding an effector necessary for formation of attaching and effacing lesions on epithelial cells), were directly regulated by both Cra and KdpE, while Z2077 was only regulated by Cra. These studies identified and confirmed new direct targets for Cra and KdpE that included putative virulence factors as well as characterized virulence factors, such as EspFu and EspG. These results map out the role of the two interacting regulators, Cra and KdpE, in EHEC pathogenesis and global gene regulation.