The human bacterial pathogen Campylobacter jejuni is able to respond to environmental stimuli utilising chemotactic motility. The bacterial senses external molecules via transmembrane sensory proteins called Transducer Like Proteins, TLPs. The specificity of the Tlp1 chemoreceptor (Cj1506c) of C. jejuni as the aspartate receptor, CcaA, and its role in chemotaxis signalling pathway were characterised by genetic and biochemical approaches including amino acid and small molecule arrays, Saturation Transfer Difference NMR spectroscopy, and mutational analysis. Yeast two-hybrid and three-hybrid analysis of protein-protein interactions showed that CcaA chemotactic signal was preferentially passed through CheV, rather than the CheW homologue of the chemotaxis signalling pathway allowing a new model for the C. jejuni chemotactic signalling pathway to be postulated.