Pellicle Biofilm Formation in Burkholderia cenocepacia J2315 is Epigenetically Regulated through WspH, a Hybrid Two-Component System Kinase-Response Regulator

• Published in: Journal of bacteriology Vol. 204; no. 5; p. e0001722
• Main Authors: Sass, Andrea, Vandenbussche, Ian, Bellich, Barbara, Cescutti, Paola, Coenye, Tom
• Format: Journal Article
• Language: English
• Published: United States American Society for Microbiology 17-05-2022
• Subjects: Anti-Bacterial Agents - metabolism; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Bacteriology; Biofilms; Burkholderia cenocepacia; Burkholderia cenocepacia - metabolism; Chemoreception; Cyclic GMP - metabolism; Gene Expression Regulation, Bacterial; Histidine; Histidine kinase; Histidine Kinase - genetics; Histidine Kinase - metabolism; Humans; Hybrid systems; Kinases; Mutants; Oxygen - metabolism; Pellicle; Phenotypes; Phosphorylation; Research Article; Signal transduction; Swimming; c-di-GMP; Burkholderia; Wsp; biofilm
• ISSN: 0021-9193; 1098-5530
• DOI: 10.1128/jb.00017-22

The chemosensory signal transduction system Wsp regulates biofilm formation and related phenotypes by influencing cyclic-di-GMP (c-di-GMP) levels in bacterial cells. This is typically achieved by activation of the diguanylate cyclase WspR, through phosphorylation of its phosphoreceiver domain. The Wsp system of Burkholderia cenocepacia J2315 is in one operon with the hybrid response regulator/histidine kinase
but lacks the diguanylate cyclase
which is located in a different operon. The expression of
, the first gene in the B. cenocepacia Wsp operon as well as pellicle biofilm formation are epigenetically regulated in B. cenocepacia J2315. To investigate whether WspH regulates pellicle biofilm formation, several mutants with altered expression of
were constructed. Mutants with increased expression of
showed accelerated pellicle biofilm formation, reduced swimming motility and increased c-di-GMP levels. This was independent of WspR phosphorylation, showing that WspR is not the cognate response receiver for histidine kinase WspH.
Biofilms are surface-attached or suspended aggregates of cells, that are problematic in the context of bacterial infections, as they provide protection from antibiotic treatment. Burkholderia cenocepacia can colonize the lung of immunocompromised patients and forms biofilms that increase its recalcitrance to antibiotic treatment. Pellicles are biofilms which form at an air-liquid interface to take advantage of the higher oxygen concentrations in this environment. How quickly pellicles are formed is crucial for the fitness of obligate aerobic bacteria such as B. cenocepacia. Cyclic-di-GMP (c-di-GMP) levels determine the transition between planktonic and biofilm lifestyle, and WspH controls c-di-GMP production. WspH is therefore important for the fitness of B. cenocepacia in environments with gradients in oxygen concentration, such as the human lung.