Swanson J, Bergström S, Robbins K, Barrera O, Corwin D, Koomey J M
Cell. 1986 Oct 24;47(2):267-76. doi: 10.1016/0092-8674(86)90449-6.
Gonococci (Gc) exhibit pilus+----pilus- "phase transitions" at high frequency, but only some of the pilus- Gc can revert to pilus+ phenotype. We examined reversible phase transitions between pilus+ Gc and a particular pilus- variant (P-rp+ phenotype) whose pilin mRNA carries a unique block of nucleotides encoding an "assembly missense" pilin polypeptide. The results show that Gc pilus+ in equilibrium with P-rp+ transitions can result from intragenic recombination in which there is nonreciprocal exchange of partially homologous DNA sequences from a partial pilin gene (in silent, storage form) into the expression locus' complete pilin gene. Hence Gc pilus phase variation, like pilus antigenic variation, can occur by gene conversion of the pilin structural gene expression locus.
淋球菌（Gc）在高频下呈现菌毛阳性（pilus+）到菌毛阴性（pilus-）的“相变”，但只有部分菌毛阴性的Gc能回复到菌毛阳性表型。我们研究了菌毛阳性Gc与一种特定的菌毛阴性变体（P-rp+表型）之间的可逆相变，该变体的菌毛蛋白mRNA携带一个独特的核苷酸片段，编码一种“组装错义”菌毛蛋白多肽。结果表明，与P-rp+处于平衡状态的菌毛阳性Gc可通过基因内重组产生，其中部分同源DNA序列（来自部分菌毛蛋白基因，以沉默、储存形式存在）非相互交换到表达位点的完整菌毛蛋白基因中。因此，Gc菌毛相变，如同菌毛抗原变异一样，可通过菌毛蛋白结构基因表达位点的基因转换发生。
