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Infect. Immun., 12 1997, 4972-4977, Vol 65, No. 12
AL Jones, D DeShazer and DE Woods
Burkholderia pseudomallei is the causative agent of melioidosis, a disease
increasingly recognized as an important cause of morbidity and mortality in
many regions of the world. B. pseudomallei is a facultative intracellular
pathogen capable of invading eukaryotic cells. We used Tn5-OT182
mutagenesis to generate mutants deficient in the ability to invade a human
type II pneumocyte cell line (A549 cells). One of these mutants, AJ1D8,
exhibited approximately 10% of the ability of the parental strain, 1026b,
to invade A549 cells. There was no difference in the abilities of 1026b and
AJ1D8 to resist killing by RAW macrophages or the human defensin HNP-1. The
nucleotide sequence flanking the Tn5-OT182 integration in AJ1D8 was
determined, and two open reading frames were identified. The predicted
proteins shared considerable homology with two-component regulatory systems
involved in the regulation of heavy-metal resistance in other organisms.
AJ1D8 was 16-fold more sensitive to Cd2+ and twofold more sensitive to Zn2+
than was 1026b but was not sensitive to any of the other heavy metals
examined. The B. pseudomallei two-component regulatory system, termed
irlRS, complemented the invasion-deficient and heavy-metal-sensitive
phenotype of AJ1D8 in trans. There was no significant difference between
the virulence of AJ1D8 and that of 1026b in infant diabetic rats and Syrian
hamsters, suggesting that the irlRS locus is probably not a virulence
determinant in these animal models of acute B. pseudomallei infection.
Copyright © 1997, American Society for Microbiology
Identification and characterization of a two-component regulatory system involved in invasion of eukaryotic cells and heavy-metal resistance in Burkholderia pseudomallei
Department of Microbiology and Infectious Diseases, University of Calgary Health Sciences Centre, Alberta, Canada.
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