title: Involvement of EnvZ-OmpR two-component system in virulence control of Escherichia coli in Drosophila melanogaster.
abstract: Bacteria adapt to environmental changes by altering gene expression patterns with the aid of signal transduction machinery called the two-component regulatory system (TCS), which consists of two protein components, a sensor kinase and response regulator. We examined the role of the TCS in bacterial adaptation to host environments using genetically tractable organisms, Escherichia coli as a pathogen and Drosophila melanogaster as a host. To determine the strength of the transcription promoters of TCS-encoding genes in Drosophila, adult flies were infected with a series of E. coli strains that expressed GFP driven by the promoters of genes coding for 27 sensor kinases and 32 response regulators of E. coli TCS followed by the measurement of fluorescence intensities. We further analyzed EnvZ-OmpR among the TCS encoded by genes having stronger promoters. A mutant E. coli strain lacking EnvZ-OmpR had a higher pathogenic effect on fly survival than that of the parental strain, and the forced expression of envZ and ompR in the mutant strain lowered its pathogenicity. The lack of EnvZ-OmpR did not affect the growth of E. coli in a culture medium as well as the level of colony-formable E. coli in flies. An increase in E. coli virulence with the loss of EnvZ-OmpR was observed in flies defective in an Imd-mediated humoral response, and both the mutant and parental strains were equally engulfed by hemocytes in vitro. These results suggest that EnvZ-OmpR mitigated the virulence of E. coli in Drosophila by a mechanism not accompanied by a change of bacterial burden. This behavior of E. coli is most likely a bacterial strategy to achieve persistent infection.
authors.affiliation: Graduate School of Natural Science & Technology, Kanazawa University, Kanazawa, Ishikawa, Japan.
authors.forename: Pattraporn
authors.initials: P
authors.lastname: Pukklay
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Nakanishi
authors.forename: Mao
authors.initials: M
authors.lastname: Nitta
authors.forename: Kaneyoshi
authors.initials: K
authors.lastname: Yamamoto
authors.forename: Akira
authors.initials: A
authors.lastname: Ishihama
authors.forename: Akiko
authors.initials: A
authors.lastname: Shiratsuchi
mesh_terms: D000818:Animals; D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000382:microbiology*; D004926:Escherichia coli / Q000235:genetics / Q000472:pathogenicity*; D004927:Escherichia coli Infections / Q000382:microbiology*; D029968:Escherichia coli Proteins / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006434:Hemocytes / Q000382:microbiology; D008297:Male; D009097:Multienzyme Complexes / Q000378:metabolism*; D010587:Phagocytosis; D011401:Promoter Regions, Genetic; D015398:Signal Transduction; D015534:Trans-Activators / Q000378:metabolism*; D014774:Virulence
chemical_list: D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D009097:Multienzyme Complexes; D015534:Trans-Activators; C112177:osmolarity response regulator proteins; D049452:Green Fluorescent Proteins; C057843:envZ protein, E coli
keywords: Drosophila; Host–bacteria interaction; Infectious disease; TCS; Two-component regulatory system; two-component regulatory system(s)