Arav-Boger Ravit, Zong Jian-Chao, Foster Charles B
Department of Pediatrics, Division of Infectious Diseases, Johns Hopkins Hospital, Baltimore, Maryland 21287-4933, USA.
Virus Genes. 2005 Aug;31(1):65-72. doi: 10.1007/s11262-005-2201-3.
Human CMV (hCMV) encodes several captured chemokine ligand and chemokine receptor genes that may play a role in immune evasion. The adjacent viral alpha-chemokine genes UL146 and UL147 appear to have duplicated subsequent to a recent gene capture event. Sequence data from multiple hCMV isolates suggest accelerated protein evolution in one of the paralogues, UL146. Extensive sequence variation was noted throughout the more rapidly evolving paralogue, although significant variation was also observed within the more slowly evolving gene, especially within a region corresponding to a possible signal peptide. In contrast to the haplotype structure observed for other hCMV genes, the distribution of nucleotide variants indicates a marked loss of linkage disequilibrium within UL146 and to a lesser extent UL147. Despite evidence of accelerated protein evolution, the rate of nonsynonymous to synonymous substitutions (d(N)/d(S)) in the more rapidly evolving paralogue was not indicative of neutral evolution, but of moderate purifying selection. The data presented here provides a unique opportunity to study the mechanisms by which a recently duplicated pair of genes has diverged and suggests a role for recombination.
人巨细胞病毒(hCMV)编码多个捕获的趋化因子配体和趋化因子受体基因,这些基因可能在免疫逃逸中发挥作用。相邻的病毒α-趋化因子基因UL146和UL147似乎在最近一次基因捕获事件后发生了复制。来自多个hCMV分离株的序列数据表明,其中一个旁系同源物UL146的蛋白质进化加速。在进化较快的旁系同源物中观察到广泛的序列变异,尽管在进化较慢的基因中也观察到显著变异,尤其是在对应于可能信号肽的区域内。与其他hCMV基因观察到的单倍型结构不同,核苷酸变异的分布表明UL146内连锁不平衡明显丧失,在较小程度上UL147也是如此。尽管有蛋白质进化加速的证据,但进化较快的旁系同源物中非同义替换与同义替换的比率(d(N)/d(S))并非表明中性进化,而是适度的纯化选择。本文提供的数据为研究最近复制的一对基因发生分化的机制提供了独特机会,并提示了重组的作用。