Abstract
The intracellular pathogen Burkholderia pseudomallei, the etiological agent of melioidosis in humans and various animals, is capable of survival and movement within the cytoplasm of host cells by a process known as actin-based motility. The bacterial factor BimA is required for actin-based motility through its direct interaction with actin, and by mediating actin polymerization at a single pole of the bacterium to promote movement both within and between cells. However, little is known about the other bacterial proteins required for this process. Here, we have investigated the role of the bimC gene (bpss1491) which lies immediately upstream of the bimA gene (bpss1492) on the B. pseudomallei chromosome 2. Conserved amongst all B. pseudomallei, B. mallei and B. thailandensis strains sequenced to date, this gene encodes an iron-binding protein with homology to a group of proteins known as the bacterial autotransporter heptosyltransferase (BAHT) family. We have constructed a B. pseudomallei bimC deletion mutant and demonstrate that it is defective in intracellular survival in HeLa cells, but not in J774.1 macrophage-like cells. The bimC mutant is defective in cell to cell spread as demonstrated by ablation of plaque formation in HeLa cells, and by the inability to form multi-nucleated giant cells in J774.1 cells. These phenotypes in intracellular survival and cell to cell spread are not due to the loss of expression and polar localization of the BimA protein on the surface of intracellular bacteria, however they do correlate with an inability of the bacteria to recruit and polymerize actin. Furthermore, we also establish a role for bimC in virulence of B. pseudomallei using a Galleria mellonella larvae model of infection. Taken together, our findings indicate that B. pseudomallei BimC plays an important role in intracellular behavior and virulence of this emerging pathogen.
Highlights
Burkholderia pseudomallei, a Gram-negative environmental saprophyte, is the causative agent of melioidosis, a potentially life-threatening infectious disease affecting both humans and animals in certain areas of the tropics (Cheng and Currie, 2005)
BimC is completely conserved amongst all B. pseudomallei, B. mallei, B. thailandensis and B. oklahomensis strains studied to date, with over 90% amino acid identity
It is notable that B. pseudomallei BimC proteins possess a 13 amino acid Cterminal extension missing from the BimC proteins of the other closely related Burkholderia species (Figure S1)
Summary
Burkholderia pseudomallei, a Gram-negative environmental saprophyte, is the causative agent of melioidosis, a potentially life-threatening infectious disease affecting both humans and animals in certain areas of the tropics (Cheng and Currie, 2005). In North East Thailand, the case fatality rate of melioidosis is around 40% and the incidence of melioidosis continues to increase annually (Limmathurotsakul et al, 2010). Recent modeling data suggests that the incidence of melioidosis is around 165,000 cases per year worldwide, of which 89,000 are fatal (Limmathurotsakul et al, 2016). The aerosol infectivity, high mortality rate, and the absence of an effective human vaccine for the prevention of melioidosis has resulted in B. pseudomallei being listed as a Tier 1 select agent in the U.S There is a continuing need to characterize virulence mechanisms of B. pseudomallei pathogenesis to inform novel strategies for disease prevention and control
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
