PMID: 27886433

Authors:

Dennehy R, Romano M, Ruggiero A, Mohamed YF, Dignam SL, Mujica Troncoso C, Callaghan M, Valvano MA, Berisio R, McClean S

Title:

The Burkholderia cenocepacia peptidoglycan-associated lipoprotein is involved in epithelial cell attachment and elicitation of inflammation.

Journal:

Cell Microbiol. 2017 May;19(5). doi: 10.1111/cmi.12691. Epub 2016 Nov 25.

Abstract:

The Burkholderia cepacia complex (Bcc) is a group of Gram-negative opportunistic pathogens causing infections in people with cystic fibrosis (CF). Bcc is highly antibiotic resistant, making conventional antibiotic treatment problematic. The identification of novel targets for anti-virulence therapies should improve therapeutic options for infected CF patients. We previously identified that the peptidoglycan-associated lipoprotein (Pal) was immunogenic in Bcc infected CF patients; however, its role in Bcc pathogenesis is unknown. The virulence of a pal deletion mutant (Deltapal) in Galleria mellonella was 88-fold reduced (p < .001) compared to wild type. The lipopolysaccharide profiles of wild type and Deltapal were identical, indicating no involvement of Pal in O-antigen transport. However, Deltapal was more susceptible to polymyxin B. Structural elucidation by X-ray crystallography and calorimetry demonstrated that Pal binds peptidoglycan fragments. Deltapal showed a 1.5-fold reduced stimulation of IL-8 in CF epithelial cells relative to wild type (p < .001), demonstrating that Pal is a significant driver of inflammation. The Deltapal mutant had reduced binding to CFBE41o(-) cells, but adhesion of Pal-expressing recombinant E. coli to CFBE41o(-) cells was enhanced compared to wild-type E. coli (p < .0001), confirming that Pal plays a direct role in host cell attachment. Overall, Bcc Pal mediates host cell attachment and stimulation of cytokine secretion, contributing to Bcc pathogenesis.