The evolution of bat nucleic acid-sensing Toll-like receptors.
We characterized the nucleic acid-sensing Toll-like receptors (TLR) of a New World bat species, the common vampire bat (Desmodus rotundus), and through a comparative molecular evolutionary approach searched for general adaptation patterns among the nucleic acid-sensing TLRs of eight different bats species belonging to three families (Pteropodidae, Vespertilionidae and Phyllostomidae). We found that the bat TLRs are evolving slowly and mostly under purifying selection and that the divergence pattern of such receptors is overall congruent with the species tree, consistent with the evolution of many other mammalian nuclear genes. However, the chiropteran TLRs exhibited unique mutations fixed in ligand-binding sites, some of which involved nonconservative amino acid changes and/or targets of positive selection. Such changes could potentially modify protein function and ligand-binding properties, as some changes were predicted to alter nucleic acid binding motifs in TLR 9. Moreover, evidence for episodic diversifying selection acting specifically upon the bat lineage and sublineages was detected. Thus, the long-term adaptation of chiropterans to a wide variety of environments and ecological niches with different pathogen profiles is likely to have shaped the evolution of the bat TLRs in an order-specific manner. The observed evolutionary patterns provide evidence for potential functional differences between bat and other mammalian TLRs in terms of resistance to specific pathogens or recognition of nucleic acids in general.
Department of Wildlife Diseases, Leibniz Institute for Zoo and Wildlife Research (IZW), Alfred-Kowalke-Straße 17, 10315, Berlin, Germany.
Marina
M
Escalera-Zamudio
Centre for GeoGenetics, Natural History Museum of Denmark, University of Copenhagen, Øster Voldgade 5-7, 1350, Copenhagen, Denmark.
M Lisandra
ML
Zepeda-Mendoza
Centro Nacional de Investigación Disciplinaria en Microbiología Animal-INIFAP, kM 15.5 carretera federal México-Toluca Col. Palo Alto, 05110, México City, Mexico.
Elizabeth
E
Loza-Rubio
Centro Nacional de Investigación Disciplinaria en Microbiología Animal-INIFAP, kM 15.5 carretera federal México-Toluca Col. Palo Alto, 05110, México City, Mexico.
Edith
E
Rojas-Anaya
Facultad de Medicina Veterinaria y Zootecnia, Universidad Veracruzana, Miguel Ángel de Quevedo Col. Unidad Veracruzana, 91710, Veracruz, Mexico.
Maria L
ML
Méndez-Ojeda
Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, Chamilpa, 62210, Cuernavaca Morelos, Mexico.
Carlos F
CF
Arias
Department of Wildlife Diseases, Leibniz Institute for Zoo and Wildlife Research (IZW), Alfred-Kowalke-Straße 17, 10315, Berlin, Germany.|Department of Veterinary Medicine, Freie Universität Berlin, Oertzenweg 19b, 14163, Berlin, Germany.
Alex D
AD
Greenwood
D000818:Animals; D002685:Chiroptera / Q000145:classification / Q000235:genetics*; D019143:Evolution, Molecular; D008957:Models, Genetic; D012641:Selection, Genetic; D017422:Sequence Analysis, DNA; D051193:Toll-Like Receptors / Q000235:genetics*
D051193:Toll-Like Receptors
bats; molecular evolution; nucleic acid-sensing Toll-like receptors; selection