Low D, Robinson E N, McGee Z A, Falkow S
Department of Pathology, University of Utah School of Medicine, Salt Lake City 84132.
Mol Microbiol. 1987 Nov;1(3):335-46. doi: 10.1111/j.1365-2958.1987.tb01940.x.
The Escherichia coli urinary tract isolate C1212 contains two pyelonephritis-associated pili (pap) DNA sequences designated here as pap-17 and pap-21. Each of these pap sequences encodes antigenically-distinct pilin monomers, pilin-17 and pilin-21, respectively. Most individual strain C1212 cells isolated from a single bacterial colony expressed pilin-21. Only a small fraction (5%) of strain C1212 cells expressed pilin-17. Most of the latter population simultaneously expressed pilin-21, but a low percentage of cells expressed pili composed of pilin-17 alone. In contrast, almost every E. coli K-12 cell containing multicopy pap-17 expressed pilin-17 at the cell surface. These results indicated that the regulation of pilin-17 expression observed for strain C1212 was lost when pap-17 was in the multicopy state. Transfer of pap-17 to a single copy vector resulted in a pilin-17 expression frequency lower than strain C1212 (1%). Using E. coli K-12 containing single copy pap-17, we found that the frequency of pilin-17 expression increased about 15-fold when pap-21 was present in multiple copies in trans. Subcloning of pap-21 showed that a 2.2 kilobase-pair DNA sequence adjacent to, but not including, the pilin-21 structural gene was sufficient for activation of pilin-17 expression.
从泌尿道分离出的大肠杆菌C1212含有两个与肾盂肾炎相关的菌毛（pap）DNA序列，这里命名为pap - 17和pap - 21。这些pap序列各自编码抗原性不同的菌毛蛋白单体，分别为菌毛蛋白 - 17和菌毛蛋白 - 21。从单个菌落分离出的大多数C1212菌株细胞表达菌毛蛋白 - 21。只有一小部分（5%）的C1212菌株细胞表达菌毛蛋白 - 17。后一组中的大多数细胞同时表达菌毛蛋白 - 21，但有一小部分细胞仅表达由菌毛蛋白 - 17组成的菌毛。相比之下，几乎每个含有多拷贝pap - 17的大肠杆菌K - 12细胞在细胞表面都表达菌毛蛋白 - 17。这些结果表明，当pap - 17处于多拷贝状态时，在C1212菌株中观察到的菌毛蛋白 - 17表达调控丧失。将pap - 17转移到单拷贝载体中导致菌毛蛋白 - 17的表达频率低于C1212菌株（1%）。使用含有单拷贝pap - 17的大肠杆菌K - 12，我们发现当pap - 21以反式多拷贝存在时，菌毛蛋白 - 17的表达频率增加了约15倍。pap - 21的亚克隆表明，与菌毛蛋白 - 21结构基因相邻但不包括该基因的一个2.2千碱基对的DNA序列足以激活菌毛蛋白 - 17的表达。
