Implication of proteins containing tetratricopeptide repeats in conditional virulence phenotypes of Legionella pneumophila
Document Type
Article
Publication Date
7-1-2012
Abstract
Legionella pneumophila, the causative agent of Legionnaires' disease, is a ubiquitous freshwater bacterium whose virulence phenotypes require a type IV secretion system (T4SS). L. pneumophila strain JR32 contains two virulence-associated T4SSs, the Dot/ Icm and Lvh T4SSs. Defective entry and phagosome acidification phenotypes of dot/icm mutants are conditional and reversed by incubating broth-grown stationary-phase cultures in water (WS treatment) prior to infection, as a mimic of the aquatic environment of Legionella. Reversal of dot/icm virulence defects requires the Lvh T4SS and is associated with a> 10-fold induction of LpnE, a tetratricopeptide repeat (TPR)-containing protein. In the current study, we demonstrated that defective entry and phagosome acidification phenotypes of mutants with changes in LpnE and EnhC, another TPR-containing protein, were similarly reversed by WS treatment. In contrast to dot/icm mutants for which the Lvh T4SS was required, reversal for the ΔlpnE or the ΔenhC mutant required that the other TPR-containing protein be present. The single and double ΔlpnE and ΔenhC mutants showed a hypersensitivity to sodium ion, a phenotype associated with dysfunction of the Dot/Icm T4SS. The ΔlpnE single and the ΔlpnE ΔenhC double mutant showed 3- to 9-fold increases in translocation of Dot/Icm T4SS substrates, LegS2/SplY and LepB. Taken together, these data identify TPR-containing proteins in a second mechanism by which the WS mimic of a Legionella environmental niche can reverse virulence defects of broth-grown cultures and implicate LpnE and EnhC directly or indirectly in translocation of Dot/Icm T4SS protein substrates. © 2012, American Society for Microbiology.
Publication Title
Journal of Bacteriology
Recommended Citation
Bandyopadhyay, P.,
Sumer, E.,
Jayakumar, D.,
Liu, S.,
Xiao, H.,
&
Steinman, H.
(2012).
Implication of proteins containing tetratricopeptide repeats in conditional virulence phenotypes of Legionella pneumophila.
Journal of Bacteriology,
194(14), 3579-3588.
http://doi.org/10.1128/JB.00399-12
Retrieved from: https://digitalcommons.mtu.edu/michigantech-p/12266
