AUTHOR=Zhang Kai , Chen Ming , He Haobin , Kou Hongyan , Lin Li , Liang Rishen 

TITLE=Genome-wide identification and characterization of toll-like receptor 5 (TLR5) in fishes

JOURNAL=Frontiers in Genetics

VOLUME=13

YEAR=2023

URL=https://www.frontiersin.org/journals/genetics/articles/10.3389/fgene.2022.1083578

DOI=10.3389/fgene.2022.1083578

ISSN=1664-8021

ABSTRACT=<p>Toll-like receptors 5 (TLR5), a member of the toll-like receptors (TLRs) family, is a class of pattern recognition receptors (PRRs) that recognize pathogen-associated molecular patterns (PAMPs). It responds to vertebrate recognition of bacterial flagellin and participates in innate immune responses. However, genome-wide identification and characterization of TLR5 in fishes have not been investigated. Here, three TLR5M isotypes (<italic>TLR5Ma</italic>, <italic>TLR5Mb1</italic>, and <italic>TLR5Mb2</italic>) and a TLR5S are all extracted from fish genomes on the basis of phylogenetic and synteny analyses. We confirmed that the non-teleost fishes have one <italic>TLR5M</italic> gene, as well as additional <italic>TLR5</italic> genes (<italic>TLR5M</italic> and <italic>TLR5S</italic>) in teleost fishes. In addition, some special teleost fishes possess two to three <italic>TLR5</italic> genes, which have undergone the fourth whole-genome duplication (WGD). According to our results, we inferred that the diversity of <italic>TLR5</italic> genes in fishes seems to be the result of combinations of WGD and gene loss. Furthermore, <italic>TLR5</italic> isoforms displayed differences at the flagellin interaction sites and viral binding sites, and showed lineage-specific, which indicated that <italic>TLR5</italic> duplicates may generate functional divergence. Bacterial experiments also supported the idea that <italic>CiTLR5Ma</italic> and <italic>CiTLR5Mb</italic> are subfunctionalized to sense bacterial flagellin. In summary, our present comparative genomic survey will benefit for further functional investigations of <italic>TLR5</italic> genes in fish.</p>