Moriya T, Kawabata S, Mizunoe Y, Amako K
Department of Bacteriology, Faculty of Medicine, Kyushu University, Fukuoka, Japan.
J Bacteriol. 1989 Dec;171(12):6629-36. doi: 10.1128/jb.171.12.6629-6636.1989.
The gene coding for the mannose-sensitive hemagglutinating fimbriae in Serratia marcescens US5 was cloned into Escherichia coli K4 with a cosmid vector system. One of the transformants, US5-1, expressed two morphologically distinct fimbriae, one that was 5-nm wide and one that was 3-nm wide. The latter fimbria was morphologically and serologically indistinguishable from that of strain US5. Genetic analysis of transformant US5-1 showed that the gene responsible for the 5-nm-wide fimbriae was located more than 10 kilobases away from the gene responsible for the 3-nm-wide fimbriae. The molecular sizes of the subunits of these two fimbriae, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, were 19 kilodaltons for the 3-nm-wide fimbriae and 20 kilodaltons for the 5-nm-wide fimbriae. Serologically, the 5-nm-wide fimbriae did not cross-react with monoclonal or polyclonal antibodies raised against the mannose-sensitive hemagglutinating fimbriae of strain US5. Strain EL101, which expressed only the 5-nm-wide fimbriae, did not agglutinate chicken or human erythrocytes. These experimental results suggest that the gene for the 5-nm-wide fimbriae is cryptic in strain US5 and is expressed in E. coli K4 only after it is moved by transformation.
将粘质沙雷氏菌US5中编码甘露糖敏感血凝菌毛的基因，用黏粒载体系统克隆到大肠杆菌K4中。其中一个转化子US5-1表达出两种形态不同的菌毛，一种宽5纳米，另一种宽3纳米。后一种菌毛在形态和血清学上与US5菌株的菌毛无法区分。对转化子US5-1的基因分析表明，负责5纳米宽菌毛的基因位于距负责3纳米宽菌毛的基因10多千碱基以外的位置。通过十二烷基硫酸钠-聚丙烯酰胺凝胶电泳测定，这两种菌毛亚基的分子大小分别为：3纳米宽的菌毛为19千道尔顿，5纳米宽的菌毛为20千道尔顿。血清学分析显示，5纳米宽的菌毛与针对US5菌株甘露糖敏感血凝菌毛产生的单克隆或多克隆抗体不发生交叉反应。只表达5纳米宽菌毛的EL101菌株不凝集鸡或人的红细胞。这些实验结果表明，5纳米宽菌毛的基因在US5菌株中是隐蔽的，只有通过转化转移到大肠杆菌K4中后才会表达。
