Methyl-accepting chemotaxis proteins 3 and 4 are responsible for Campylobacter jejuni chemotaxis and jejuna colonization in mice in response to sodium deoxycholate

Methyl-accepting chemotaxis proteins (MCPs), also termed transducer-like proteins (Tlps), serve as sensors in bacterial chemotactic signalling, and detect attractants and promote bacterial movement towards suitable sites for colonization. Campylobacter jejuni is a leading cause of human enteritis, but the mechanisms responsible for bacterial chemotaxis and early colonization in the jejunum of hosts are poorly understood. In the present study, we identified several types of bile and sodium deoxycholate (SDC) acting as chemotactic attractants of C. jejuni strain NCTC 11168-O in vitro, in which SDC was the most efficient chemoattractant. In mice with bile duct ligation, the wild-type strain displayed a markedly attenuated ability for colonization. Blockage of Tlp3 or Tlp4 protein with antibody or disruption of the tlp3 or tlp4 gene (Dtlp3 or Dtlp4) caused a significant inhibition of SDC-induced chemotaxis and attenuation for colonization on jejuna mucosa in mice of the bacterium. Disruption of both the genes (Dtlp3/Dtlp4) resulted in the absence of bacterial chemotaxis and colonization, while the tlp-gene-complemented mutants (CDtlp3 and CDtlp4) reacquired these abilities. The results indicate that SDC is an effective chemoattractant for C. jejuni, and Tlp3 and Tlp4 are the SDC-specific sensor proteins responsible for the bacterial chemoattraction.