The dCache Domain of the Chemoreceptor Tlp1 in Campylobacter jejuni Binds and Triggers Chemotaxis toward Formate

Abstract

Chemotaxis is important for Campylobacter jejuni to colonize favorable niches in the gastrointestinal tract of its host. However, there is still a lack of knowledge about the ligand molecules for C. jejuni chemoreceptors.

Identification of a dCache-type chemoreceptor in Campylobacter jejuni that specifically mediates chemotaxis towards methyl pyruvate

“…The strains and plasmids used in this study are listed in Supplementary Table S1 . C. jejuni strains were grown in Mueller–Hinton (MH) medium ( Duan et al, 2023 ) and Brucella broth supplemented with 10% filter-sterilized fetal bovine serum (ExCell Bio, China) ( Duan et al, 2023 ) for the growth and chemotaxis experiments, respectively, under microaerobic conditions (85% N 2 , 10% CO 2 , and 5% O 2 ), at 37°C. E. coli strains were grown in Luria-Bertani medium (Oxoid, United States), at 37°C, for routine culture; in Tryptone broth (1% tryptone and 0.5% NaCl), at 34°C, for the chemotaxis experiments; and in Medium A ( Yuan et al, 2017 ), pH 7.2, at 37°C, for measuring the responses of hybrid kinases in E. coli MG1655 strains, under aerobic conditions.…”

“…The His-tag dye (MO-L018 RED-tris-NTA, NanoTemper, Germany) was adjusted to a final concentration of 25 nM and used to label the purified protein with a His-tag. The compound was diluted to a series of concentrations in phosphate-buffered saline ( Duan et al, 2023 ) with 0.05% Tween 20 (PBS-T) buffer and mixed in a ratio of 1:1 with protein. The mixtures were loaded into capillaries (Monolith ™ Series capillaries, NanoTemper) by means of capillary action.…”

“…The C. jejuni WT NCTC 11168 was used to generate the 11168ΩTlp11 strain by means of double-crossover homologous recombination, using a suicide plasmid containing homologous arms that flanked the target gene ( Duan et al, 2023 ). The insertion site for tlp11 was selected between 16 s RNA and 23 s RNA in the genome of C. jejuni NCTC 11168.…”

“…The discovery of direct-binding ligands of chemoreceptors is key to understanding the physiological role of chemotactic behavior. However, except for several chemoreceptors ( Day et al, 2016 ; Khan et al, 2020 ; Elgamoudi et al, 2021 ; Taha et al, 2022 ; Duan et al, 2023 ), there remain gaps in the identification of C. jejuni chemoreceptor ligands and understanding of their functions.…”

“…Exploring whether ligand binding to a specific receptor, the LBD, can transmit signals is crucial for revealing the physiological function of the ligand. The construction of chimeras is a potential tool to elucidate the ligand specificities and signaling properties of target receptor LBDs ( Bi et al, 2016 ; Luu et al, 2019 ; Duan et al, 2023 ). Because some transmembrane chemoreceptors and histidine kinases have similar topologies, the target LBD can be fused with a chemoreceptor or histidine kinase to form a hybrid chemoreceptor or hybrid kinase.…”