iBB

Burkholderia cenocepacia is a human contact-dependent pathogenic bacterium known for its capacity of causing severe opportunistic respiratory infections. B. cenocepacia uses a complex machinery for primary adherence with host cells. In a recent paper published in Scientific Reports, a BSRG-iBB team (Andreia Pimenta, Nuno Bernardes, Dalila Mil-Homens and Arsénio M Fialho) together with Marta M Alves from CQE, IST, have developed a RNASeq-based approach that led to identify adhesion candidate genes that were not previously reported in the context of a B. cenocepacia infection. This study presents a innovative technique in which their use Giant Plasma Membrane Vesicles (GPMVs) from a bronchial epithelial cell line as a cell-like alternative to investigate the steps involved in the adhesion process of B. cenocepacia.

The role of the bcaC  trimeric autotransporter adhesion (TAA) gene in the virulence of Burkholderia cenocepacia has been disclosed by iBB researchers Andreia Pimenta, Dalila Mil-Homens, Sandra Pinto and Arsénio Fialho in a report published in Microbes and Infection. TAAs are homotrimeric proteins of the outer membrane of many Gram-negative pathogens that play a key role in adhesion to host cells. Two insertional-mutants for TAA bcaC and histidine kinase (HK) BCAM0218 genes were constructed. Findings indicate that bcaC encodes for a large multifunctional TAA that has hemagglutination activity and is also required for maximal host cell adherence. The neighbor BCAM0218 HK encoding gene was identified as a critical player that negatively controls the expression of the bcaC TAA gene. All together, the findings represent a step forward for a better characterization of the subset of B. cenocepacia TAA-encoding genes. This article was selected as the highlighted article of the July 2020 issue of the Microbes and Infection journal.

B. cenocepacia is a contact-dependent bacterium known for its capacity of causing respiratory infections. Among a panel of adhesins used by B. cenocepacia to contact with host cells, trimeric autotransporter adhesins (TAAs) are of particular interest. In a recent paper published in Cellular Microbiology, a BSRG-iBB team (Andreia Pimenta, Nuno Bernardes, Dalila Mil-Homens and Arsénio M Fialho) together with Michelle Kilcoyne and Lokesh Joshi from the National University of Ireland Galway, Galway, Ireland, were able to uncover the roles of the TAA BCAM2418, as an adhesin and the type of host glycans that serve as recognition targets. This work reveals the importance of BCAM2418 as a mediator of early host-bacteria crosstalk.

Burkholderia cenocepacia is a human contact-dependent pathogenic bacterium known for its capacity of causing severe and persistent opportunistic respiratory infections. The initial contact between bacteria and the human epithelial cells are crucial for the success of the infection. B. cenocepacia uses very complex machinery for primary adherence with host cells. Among those, the class of trimeric autotransporter adhesins (TAAs) deserves particular attention. In this study, published in MicrobiologyOpen, BSRG-iBB researchers Andreia Pimenta, Dalila Mil-Homens and Arsénio M. Fialho demonstrated that BCAM2418, a TAA from the epidemic strain B. cenocepacia K56-2, shows an on–off switch after an initial colonization period, exhibits a strong expression dependent on the host cell type, and enhances its function on cell adhesion. Moreover, this study found that overexpression of BCAM2418 gene contributes to the bacterial cell adhesion to host cells and is dependent on recognition of O‐linked glycans from the host cell membranes. Overall, this study not only defines the behavior of this particular TAA during the step of bacterial adhesion but also provide insights aiming to determine potential targets for therapeutic proposals.