Diversity of transducer-like proteins (Tlps) in Campylobacter

Abstract

Campylobacter transducer-like proteins (Tlps), also known as methyl-accepting chemotaxis proteins (MCPs), are associated with virulence as well as niche and host adaptation. While functional attributes of these proteins are being elucidated, little has been published regarding their sequence diversity or chromosomal locations and context, although they appear to define invertible regions within Campylobacter jejuni genomes. Genome assemblies for several species of Campylobacter were obtained from the publicly available NCBI repositories. Genomes from all isolates were obtained from GenBank and assessed for Tlp content, while data from isolates with complete, finished genomes were used to determine the identity of Tlps as well as the gene content of putative invertible elements (IEs) in C. jejuni (Cj) and C. coli (Cc). Tlps from several Campylobacter species were organized into a nomenclature system and novel Tlps were defined and named for Cj and Cc. The content of Tlps appears to be species-specific, though diverse within species. Cj and Cc carried overlapping, related Tlp content, as did the three C. fetus subspecies. Tlp1 was detected in 88% of Cj isolates and approximately 43% of Cc, and was found in a different conserved chromosomal location and genetic context in each species. Tlp1 and Tlp 3 predominated in genomes from Cj whereas other Tlps were detected less frequently. Tlp13 and Tlp20 predominated in genomes from Cc while some Cj/Cc Tlps were not detected at all. Tlps 2–4 and 11–20 were less frequently detected and many showed sequence heterogeneity that could affect substrate binding, signal transduction, or both. Tlps other than Tlp1, 7, and 10 had substantial sequence identity in the C-terminal half of the protein, creating chromosomal repeats potentially capable of mediating the inversion of large chromosomal DNA. Cj and Cc Tlps were both found in association with only 14 different genes, indicating a limited genomic context. In Cj these Tlps defined IEs that were for the most part found at a single chromosomal location and comprised of a conserved set of genes. Cc IEs were situated at very different chromosomal locations, had different structures than Cj IEs, and were occasionally incomplete, therefore not capable of inversion. Tlps may have a role in Campylobacter genome structure and dynamics as well as acting as chemoreceptors mediating chemotactic responses.

Genome-Wide Identification of Host-Segregating Single-Nucleotide Polymorphisms for Source Attribution of Clinical Campylobacter coli Isolates

“…To contextualize host-segregating SNPs within genes, Blast-x annotation identified 32 coding regions for known proteins, 5 hypothetical proteins as well as 4 intergenic regions (Suppl Table S1). Several SNPs (n=27) were found in proteins involved in motility, which plays an important role in bacterial host adaptation: 12 and 4 SNPs in flagellar proteins FliK (with 2 SNPs in its basal-body rod modification protein FlgD) and FliD respectively, known to modulate flagellar hook length (37) and to act as an immunodominant protein (38); 5 SNPs from methyl-accepting chemotaxis proteins (TLPlike protein (39)) or intergenic regions before methyl-accepting chemotaxis proteins; as well as 4 on October 9, 2020 at UNIV OF BATH http://aem.asm.org/ Downloaded from SNPs in one aerotaxis receptor belonging to CetC, a protein involved in regulating energy taxis (40).…”

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

“…Although the ligand specificities of several C. jejuni chemoreceptors have been reported ( 17 , 50 ), studies on the ligands of chemoreceptors and their roles in C. jejuni survival and growth are still rare. To our knowledge, 13 chemoreceptors have been reported in C. jejuni ( 9 , 51 ). Therefore, it is difficult to screen the ligand molecules of individual chemoreceptors.…”

“…The C. jejuni strain NCTC 11168 contains 10 putative chemoreceptors that can be divided into different groups, according to their topologies ( 9 , 10 ). Chemoreceptors Tlp1 to Tlp4, Tlp7, and Tlp10 belong to the class I topology group, which is composed of a periplasmic ligand-binding domain (LBD), two transmembrane helices, and a cytoplasmic signaling domain ( 11 ).…”

Extracellular vesicles in the pathogenesis of Campylobacter jejuni

“…These proteins are classified into three groups (A, B, and C) depending on their structure. Novel Tlp proteins were recently identified (Tlp14-25), in addition to the 13 Tlps previously described [22][23][24]. Once the external stimuli bind to Tlps, a signal is relayed to chemotaxis proteins (Che) in the cytoplasm.…”