Unraveling the role of H-NS-like proteins and environmental stressors on the pathoadaptive evolution of Burkholderia multivorans to the cystic fibrosis lung

05/22/2025

Upon infection of the cystic fibrosis (CF) lung, Burkholderia multivorans undergo a process of pathoadaptation that directs the transition from an environmental opportunist to a persistence pathogen. This process involves genomic and phenotypic changes triggered by the challenging CF-lung environment. The present work delves into the intricate adaptation mechanisms employed by B. multivorans within the CF-lung, revealing a parallelism between in vitro experimentally evolved populations and CFlongitudinal series of clinical isolates. The identification of novel regulatory circuits was successfully achieved with the discovery of H-NS-like nucleoid structuring proteins as regulators of polysaccharide biosynthesis, as well as of other virulence traits. Furthermore, such regulation might be achieved by a functional cooperation between some of the conserved H-NS-like proteins encoded by B. multivorans, showing the complexity of this network. With the aim of identifying new players of the pathoadaptive response of B. multivorans, in vitro and in vivo experimental evolution was employed. Cocultures with Staphylococcus aureus were successful, but Pseudomonas aeruginosa completely inhibited the growth of B. multivorans. Evolution of B. multivorans in the presence of the aminoglycoside tobramycin identified mutations in fusA and ttgR/mexZ genes, although genes implicated in cell surface modifications such as lipopolysaccharide and phospholipid biosynthesis might also contribute to resistance, especially in biofilms. Evolution of B. multivorans in Galleria mellonella insect model resulted in evolved populations with increased virulence. Mutation in genes associated with flagella and pili biosynthesis are strongly selected by the immune system of this host. This, together with the fact that populations evolved under the immune system selection were less phagocytosed by macrophages, demonstrates that evasion is likely an important route to persistence in the host. Overall, the work here described contributes to the understanding of B. multivorans' responses to diKerent CF-lung stressors, creating new insights for future advancements in bacterial persistence and infections management.

Authors in the community:

• 

  S

  Sara Caracol Gomes

  ist188117

Supervisors of this institution:

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  L

  Leonilde de Fátima Morais Moreira

  ist14082

biological-sciences - Biological sciences

eng - English

Instituto Superior Técnico