Ortiz M, Kaessmann H, Zhang K, Bashirova A, Carrington M, Quintana-Murci L, Telenti A
Institute of Microbiology, University of Lausanne, Lausanne, Switzerland.
Genes Immun. 2008 Sep;9(6):483-92. doi: 10.1038/gene.2008.40. Epub 2008 Jun 5.
The CD209 gene family that encodes C-type lectins in primates includes CD209 (DC-SIGN), CD209L (L-SIGN) and CD209L2. Understanding the evolution of these genes can help understand the duplication events generating this family, the process leading to the repeated neck region and identify protein domains under selective pressure. We compiled sequences from 14 primates representing 40 million years of evolution and from three non-primate mammal species. Phylogenetic analyses used Bayesian inference, and nucleotide substitutional patterns were assessed by codon-based maximum likelihood. Analyses suggest that CD209 genes emerged from a first duplication event in the common ancestor of anthropoids, yielding CD209L2 and an ancestral CD209 gene, which, in turn, duplicated in the common Old World primate ancestor, giving rise to CD209L and CD209. K(A)/K(S) values averaged over the entire tree were 0.43 (CD209), 0.52 (CD209L) and 0.35 (CD209L2), consistent with overall signatures of purifying selection. We also assessed the Toll-like receptor (TLR) gene family, which shares with CD209 genes a common profile of evolutionary constraint. The general feature of purifying selection of CD209 genes, despite an apparent redundancy (gene absence and gene loss), may reflect the need to faithfully recognize a multiplicity of pathogen motifs, commensals and a number of self-antigens.
在灵长类动物中编码C型凝集素的CD209基因家族包括CD209（树突状细胞特异性细胞间粘附分子3结合非整合素，DC-SIGN）、CD209L（肝/淋巴结特异性ICAM-3抓取非整合素，L-SIGN）和CD209L2。了解这些基因的进化有助于理解产生该家族的复制事件、导致重复颈部区域的过程，并识别处于选择压力下的蛋白质结构域。我们汇编了代表4000万年进化历程的14种灵长类动物以及三种非灵长类哺乳动物物种的序列。系统发育分析采用贝叶斯推断法，核苷酸替代模式通过基于密码子的最大似然法进行评估。分析表明，CD209基因起源于类人猿共同祖先中的首次复制事件，产生了CD209L2和一个祖先CD209基因，而该祖先CD209基因又在旧世界灵长类动物的共同祖先中发生复制，产生了CD209L和CD209。整个树的平均K(A)/K(S)值分别为0.43（CD209）、0.52（CD209L）和0.35（CD209L2），与纯化选择的总体特征一致。我们还评估了Toll样受体（TLR）基因家族，它与CD209基因具有共同的进化约束特征。尽管存在明显的冗余（基因缺失和基因丢失），但CD209基因纯化选择的一般特征可能反映了忠实地识别多种病原体基序、共生菌和一些自身抗原的需求。
