title: Bordetella adenylate cyclase toxin interacts with filamentous haemagglutinin to inhibit biofilm formation in vitro.
abstract: Bordetella pertussis, the causative agent of whooping cough, secretes and releases adenylate cyclase toxin (ACT), which is a protein bacterial toxin that targets host cells and disarms immune defenses. ACT binds filamentous haemagglutinin (FHA), a surface-displayed adhesin, and until now, the consequences of this interaction were unknown. A B. bronchiseptica mutant lacking ACT produced more biofilm than the parental strain; leading Irie et al. to propose the ACT-FHA interaction could be responsible for biofilm inhibition. Here we characterize the physical interaction of ACT with FHA and provide evidence linking that interaction to inhibition of biofilm in vitro. Exogenous ACT inhibits biofilm formation in a concentration-dependent manner and the N-terminal catalytic domain of ACT (AC domain) is necessary and sufficient for this inhibitory effect. AC Domain interacts with the C-terminal segment of FHA with ∼650 nM affinity. ACT does not inhibit biofilm formation by Bordetella lacking the mature C-terminal domain (MCD), suggesting the direct interaction between AC domain and the MCD is required for the inhibitory effect. Additionally, AC domain disrupts preformed biofilm on abiotic surfaces. The demonstrated inhibition of biofilm formation by a host-directed protein bacterial toxin represents a novel regulatory mechanism and identifies an unprecedented role for ACT.
authors.affiliation: Division of Infectious Diseases and International Health, Department of Medicine, University of Virginia, Charlottesville, VA, USA.
authors.forename: Casandra
authors.initials: C
authors.lastname: Hoffman
authors.affiliation: Division of Infectious Diseases and International Health, Department of Medicine, University of Virginia, Charlottesville, VA, USA.
authors.forename: Joshua
authors.initials: J
authors.lastname: Eby
authors.affiliation: Division of Infectious Diseases and International Health, Department of Medicine, University of Virginia, Charlottesville, VA, USA.
authors.forename: Mary
authors.initials: M
authors.lastname: Gray
authors.affiliation: Department of Microbiology, Immunology and Cell Biology, School of Medicine, West Virginia University, Morgantown, WV, USA.
authors.forename: F
authors.initials: F
authors.lastname: Heath Damron
authors.affiliation: School of Medicine, University of North Carolina, Chapel Hill, NC, USA.
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Melvin
authors.affiliation: School of Medicine, University of North Carolina, Chapel Hill, NC, USA.
authors.forename: Peggy
authors.identifier: 0000-0003-3726-3990
authors.initials: P
authors.lastname: Cotter
authors.affiliation: Division of Infectious Diseases and International Health, Department of Medicine, University of Virginia, Charlottesville, VA, USA.
authors.forename: Erik
authors.initials: E
authors.lastname: Hewlett
mesh_terms: D037361:Adenylate Cyclase Toxin / Q000235:genetics / Q000378:metabolism*; D018829:Adhesins, Bacterial / Q000235:genetics / Q000378:metabolism*; D018441:Biofilms / Q000254:growth & development*; D016950:Bordetella bronchiseptica / Q000235:genetics / Q000378:metabolism*; D001886:Bordetella pertussis / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D006388:Hemagglutinins / Q000378:metabolism; D010566:Virulence Factors, Bordetella / Q000235:genetics / Q000378:metabolism*
chemical_list: D037361:Adenylate Cyclase Toxin; D018829:Adhesins, Bacterial; D006388:Hemagglutinins; D010566:Virulence Factors, Bordetella; C065273:filamentous hemagglutinin adhesin, Bordetella pertussis