title: Selectivity of Human TLR9 for Double CpG Motifs and Implications for the Recognition of Genomic DNA.
abstract: TLR9 acts as a first-line host defense against pathogens recognizing DNA comprising unmethylated CpG motifs present in bacteria and viruses. Species- and sequence-specific recognition differences were demonstrated for TLR9 receptors. Activation of human (h)TLR9 requires a pair of closely positioned CpG motifs within oligodeoxyribonucleotides (ODNs), whereas mouse TLR9 is effectively activated by an ODN with a single CpG motif. Molecular model-directed mutagenesis identified two regions, site A and site B, as important for receptor activation. Amino acid residues Gln346and Arg348within site A contribute to the sequence-specific recognition by hTLR9 in determining the bias for two appropriately spaced CpG motifs within immunostimulatory ODNs. Mutation of Gln562at site B, in combination with Gln346and Arg348mutations of mouse counterparts, increased activation of hTLR9 by mouse-specific ODN, mammalian genomic DNA, and bacterial DNA. We propose that the double CpG motif sequence-specificity of hTLR9 results in decreased activation by ODNs with a lower frequency of CpG motifs, such as from mammalian genomic DNA, which increases hTLR9 selectivity for pathogen versus host DNA.
authors.affiliation: Department of Synthetic Biology and Immunology, National Institute of Chemistry, SI-1000 Ljubljana, Slovenia.
authors.forename: Jelka
authors.initials: J
authors.lastname: Pohar
authors.affiliation: Division of Innate Immunity, Department of Microbiology and Immunology, University of Tokyo, Minatoku, Tokyo 108-8639, Japan.
authors.forename: Chikako
authors.initials: C
authors.lastname: Yamamoto
authors.affiliation: Division of Innate Immunity, Department of Microbiology and Immunology, University of Tokyo, Minatoku, Tokyo 108-8639, Japan.
authors.forename: Ryutaro
authors.initials: R
authors.lastname: Fukui
authors.affiliation: Department of Synthetic Biology and Immunology, National Institute of Chemistry, SI-1000 Ljubljana, Slovenia.
authors.forename: Miša-Mojca
authors.initials: MM
authors.lastname: Cajnko
authors.affiliation: Division of Innate Immunity, Department of Microbiology and Immunology, University of Tokyo, Minatoku, Tokyo 108-8639, Japan.|Laboratory of Innate Immunity, Center for Experimental Medicine and Systems Biology, Institute of Medical Science, University of Tokyo, Minatoku, Tokyo 108-8639, Japan; and.
authors.forename: Kensuke
authors.initials: K
authors.lastname: Miyake
authors.affiliation: Department of Synthetic Biology and Immunology, National Institute of Chemistry, SI-1000 Ljubljana, Slovenia; roman.jerala@ki.si mojca.bencina@ki.si.|EN-FIST Centre of Excellence, SI-1000 Ljubljana, Slovenia.
authors.forename: Roman
authors.initials: R
authors.lastname: Jerala
authors.affiliation: Department of Synthetic Biology and Immunology, National Institute of Chemistry, SI-1000 Ljubljana, Slovenia; roman.jerala@ki.si mojca.bencina@ki.si.|EN-FIST Centre of Excellence, SI-1000 Ljubljana, Slovenia.
authors.forename: Mojca
authors.initials: M
authors.lastname: Benčina
mesh_terms: D000818:Animals; D018899:CpG Islands / Q000235:genetics*; D004269:DNA, Bacterial / Q000235:genetics* / Q000276:immunology; D016678:Genome / Q000235:genetics*; D057809:HEK293 Cells; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D059372:Nucleotide Motifs / Q000235:genetics*; D009838:Oligodeoxyribonucleotides / Q000235:genetics; D000067996:RAW 264.7 Cells; D015398:Signal Transduction; D013045:Species Specificity; D051217:Toll-Like Receptor 9 / Q000235:genetics / Q000378:metabolism*
chemical_list: D004269:DNA, Bacterial; D009838:Oligodeoxyribonucleotides; C495371:TLR9 protein, human; D051217:Toll-Like Receptor 9