Tam Connie K P, Hackett Jim, Morris Christina
Department of Biochemistry, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China.
Infect Immun. 2004 Jan;72(1):22-8. doi: 10.1128/IAI.72.1.22-28.2004.
Salmonella enterica serovar Typhi uses type IVB pili to facilitate bacterial self-association, but only when the PilV proteins (potential minor pilus proteins) are not synthesized. This pilus-mediated event may be important in typhoid fever pathogenesis. We initially show that S. enterica serovar Paratyphi C strains harbor a pil operon very similar to that of serovar Typhi. An important difference, however, is located in the shufflon which concludes the pil operon. In serovar Typhi, the Rci recombinase acts upon two 19-bp inverted repeats to invert the terminal region of the pilV gene, thereby disrupting PilV synthesis and permitting bacterial self-association. In serovar Paratyphi C, however, the shufflon is essentially inactive because each of the Rci 19-bp substrates has acquired a single base pair insertion. A PilV protein is thus synthesized whenever the pil operon is active, and bacterial self-association therefore does not occur in serovar Paratyphi C. The data thus suggest that serovar Typhi bacterial self-association using type IVB pili may be important in the pathogenesis of epidemic enteric fever.
伤寒沙门氏菌血清型伤寒杆菌利用IVB型菌毛促进细菌自我聚集，但仅在不合成PilV蛋白（潜在的次要菌毛蛋白）时才会发生。这种菌毛介导的事件可能在伤寒热发病机制中起重要作用。我们首先表明，副伤寒沙门氏菌血清型丙菌株含有一个与伤寒沙门氏菌血清型菌毛操纵子非常相似的菌毛操纵子。然而，一个重要的区别在于菌毛操纵子末端的改组序列。在伤寒沙门氏菌血清型中，Rci重组酶作用于两个19bp的反向重复序列，使pilV基因的末端区域发生倒位，从而破坏PilV的合成并允许细菌自我聚集。然而，在副伤寒沙门氏菌血清型丙中，改组序列基本上是无活性的，因为每个Rci 19bp底物都获得了一个单碱基对插入。因此，每当菌毛操纵子活跃时就会合成PilV蛋白，因此在副伤寒沙门氏菌血清型丙中不会发生细菌自我聚集。这些数据因此表明，伤寒沙门氏菌血清型利用IVB型菌毛进行细菌自我聚集可能在流行性肠热病的发病机制中起重要作用。
