Chemotactic motility and biofilm formation in Campylobacter jejuni are coordinated by the CheAYWV system

Published on (GMT) by Arnoud van Vliet
Chemotaxis is the ability of motile bacteria to coordinate swimming behaviour to navigate a changeable environment, by sensing environmental conditions through receptors and transducing these signals to the flagellar motor. In the foodborne bacterial pathogen Campylobacter jejuni, flagellar motility and chemotaxis are required for intestinal colonisation and virulence. Here we present a systematic characterisation of the CheAYVW chemotaxis system of C. jejuni and its role in chemotactic motility and biofilm formation. Inactivation of the core chemotaxis genes (cheA, cheY, cheV or cheW) impaired chemotactic motility but not flagellar assembly. Inactivation of cheV or presence of two copies of cheV impaired chemotaxis to a greater extent than inactivation of cheW or presence of two copies of cheW. A cheY mutant swam in clockwise loops and this behaviour was complemented by wildtype cheY or a cheY gene lacking the D7 conserved phosphorylation site, but not by cheY lacking the D53 metal-binding site. Deletion of the CheY-like received domain from the cheA gene did not impair chemotactic motility, nor could this domain complement a cheY mutant. The cj0350 gene was identified as encoding a putative CheX phosphatase, and the presence of two copies of cj0350 resulted in reduced chemotactic motility. Finally, inactivation of any of the core chemotaxis genes interfered with the ability to form a distinct biofilm at an air-media interface. This work shows that interference with the Campylobacter chemotaxis system at any level disrupts optimal chemotactic motility, and also affects transmission modes such as provided by biofilm formation.
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