title: Identification of a transcriptional regulator that controls intracellular gene expression in Salmonella Typhi.
abstract: Salmonella enterica serovar Typhi (S. Typhi), the aetiological agent of typhoid fever, is an exclusively human pathogen. Little is known about specific factors that may confer to this bacterium its unique pathogenic features. One of these determinants is CdtB, a homologue of the active subunit of the cytolethal distending toxin, which causes DNA damage leading to cell cycle arrest and distension of intoxicated cells. A unique property of S. Typhi CdtB is that it is only synthesized when this bacterium is within an intracellular compartment. Through a genetic screen, we have identified a transcriptional regulatory protein that controls the intracellular expression of cdtB. This regulator, which we have named IgeR, is a member of the DeoR family of transcriptional regulatory proteins and is highly conserved in all S. enterica serovars. IgeR directly binds the cdtB promoter and represses its expression in the extracellular environment. Microarray analysis identified additional IgeR-regulated genes that are involved in virulence. Constitutive expression of igeR resulted in the reduction of intracellular expression of cdtB by S. Typhi and in significant impairment of the virulence of Salmonella enterica serovar Typhimurium (S. Typhimurium) in mice. We propose that IgeR may co-ordinate gene expression during Salmonella's transition from an extracellular to an intracellular environment.
authors.affiliation: Section of Microbial Pathogenesis, Yale University School of Medicine, Boyer Center for Molecular Medicine, New Haven, CT 06536, USA.
authors.forename: Erik
authors.initials: E
authors.lastname: Haghjoo
authors.forename: Jorge E
authors.initials: JE
authors.lastname: Galán
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001427:Bacterial Toxins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D004847:Epithelial Cells; D005260:Female; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D007422:Intestines / Q000166:cytology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D012480:Salmonella Infections / Q000382:microbiology; D012485:Salmonella typhi / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity*; D012486:Salmonella typhimurium / Q000472:pathogenicity; D014158:Transcription, Genetic; D014435:Typhoid Fever / Q000382:microbiology; D014774:Virulence
chemical_list: D001426:Bacterial Proteins; D001427:Bacterial Toxins; D012097:Repressor Proteins; C067044:cytolethal distending toxin