orals 5th Asia-Pacific NMR Symposium 2013

Characterisation of a Multi-ligand Binding Chemoreceptor CcmL (Tlp3) of Campylobacter jejuni.  (#59)

Jennifer C Wilson 1 , Hossinur Rahman 1 , King M Rebecca 1 , Lucy K Shewell 1 , Evgeny A Semchenko 1 , Lauren E Hartley-Tassell 1 , Christopher J Day 1 , Victoria Korolik 1
  1. Griffith University, Southport, Qld, Australia

Campylobacter jejuni is the leading cause of human gastroenteritis worldwide with over 500 million cases annually. Chemotaxis and motility have been identified as important virulence factors associated with C. jejuni colonisation. Group A transducer-like proteins (Tlps) are responsible for sensing the external environment for bacterial movement to or away from a chemical gradient or stimulus. In this study, we have demonstrated Cj1564 (Tlp3) to be a multi-ligand binding chemoreceptor and report direct evidence supporting the involvement of Cj1564 (Tlp3) in the chemotaxis signalling pathway via small molecule arrays, surface plasmon and nuclear magnetic resonance (SPR and NMR) as well as chemotaxis assays of wild type and isogenic mutant strains. A modified nutrient depleted chemotaxis assay was further used to determine positive or negative chemotaxis with specific ligands. Here we demonstrate the ability of Cj1564 to interact with the chemoattractants isoleucine, purine, malic acid and fumaric acid and chemorepellents lysine, glucosamine, succinic acid, arginine and thiamine. An isogenic mutant of cj1564 was shown to alter phenotypic characteristics of C. jejuni, encompassing bacterial cell shape, motility, autoagglutination behaviour and biofilm formation. Additionally, protein-protein interaction studies revealed signal transduction initiation through the scaffolding proteins CheV and CheW in the chemotaxis sensory pathway. We demonstrate Cj1564 to have a role in invasion as in in vitro assays the tlp3 isogenic mutant has reduced ability to adhere and invade cultured epithelial cell line; interestingly however, colonisation ability of avian caeca appears to be unaltered. This is the first report characterising Cj1564 as a multi-ligand receptor for C. jejuni, we propose to name this receptor CcmL, Campylobacter chemoreceptor for multiple ligands. In conclusion, this study identifies a novel multifunctional role for C. jejuni CcmL chemoreceptor and illustrates its involvement in the chemotaxis pathway and subsequent survival of this organism in the host.