Li J, Nelson K, McWhorter A C, Whittam T S, Selander R K
Institute of Molecular Evolutionary Genetics, Pennsylvania State University, University Park 16802.
Proc Natl Acad Sci U S A. 1994 Mar 29;91(7):2552-6. doi: 10.1073/pnas.91.7.2552.
The fliC gene, which encodes phase 1 flagellin, was sequenced in strains of 15 Salmonella enterica serovars expressing flagellar antigenic factors of the g series. The occurrence of each of the flagellin serotypes g,m, m,t, and g,z51 in distantly related strains is the result of horizontal exchange of DNA, as indicated by identity or close similarity in nucleotide sequence of all or parts of the antigenic factor-determining central region of fliC. The flagellin genes of some serovars are complex mosaic structures composed of diverse segments derived through multiple recombination events. Thus, recombination of horizontally transferred segments (intragenic) or entire genes (assortative) within and among subspecies is identified as a major evolutionary mechanism generating both allelic variation at the fliC locus and serovar diversity in natural populations. Evidence that flagellar serological diversity is promoted by diversifying selection in adaptation to host immune defense system or flagellotropic phage is discussed.
对表达g系列鞭毛抗原因子的15种肠炎沙门氏菌血清型菌株的fliC基因（编码1期鞭毛蛋白）进行了测序。在远缘菌株中出现的每种鞭毛蛋白血清型g、m、m、t和g、z51是DNA水平交换的结果，这由fliC抗原因子决定中心区域全部或部分核苷酸序列的同一性或高度相似性表明。一些血清型的鞭毛蛋白基因是复杂的镶嵌结构，由通过多次重组事件衍生的不同片段组成。因此，亚种内和亚种间水平转移片段（基因内）或整个基因（选型）的重组被确定为在自然群体中产生fliC位点等位基因变异和血清型多样性的主要进化机制。讨论了关于在适应宿主免疫防御系统或嗜鞭毛噬菌体过程中多样化选择促进鞭毛血清学多样性的证据。
