Russo T A, Guenther J E, Wenderoth S, Frank M M
Bacterial Pathogenesis Unit, National Institute of Allergy and Infectious Disease, National Institutes of Health, Bethesda, Maryland 20892.
Mol Microbiol. 1993 Jul;9(2):357-64. doi: 10.1111/j.1365-2958.1993.tb01696.x.
Transposon mutagenesis, using IS50L::phoA(Tn-phoA), was performed in a K54/O4/H5 blood isolate of Escherichia coli (CP9), to generate a library of random mutants. Five hundred and twenty-six independent CP9 TnphoA mutants were isolated with active gene fusions to alkaline phosphatase. From this mutant library, eight capsule-deficient strains were detected and were found to have a single copy of TnphoA. Sixteen additional capsule deficient mutants with TnphoA inserts were subsequently obtained that did not possess active PhoA fusions. In conjunction with the initial eight capsule-deficient isolates we have defined genes on three different XbaI fragments as being involved in capsule production. Generalized transduction with the bacteriophage T4 established that these insertions were responsible for the loss of capsule and that they are linked. These capsule-deficient strains can be used to assess the pathogenic role of the K54 capsular polysaccharide.
利用IS50L::phoA（Tn-phoA）转座子诱变技术，在大肠杆菌（CP9）的K54/O4/H5血液分离株中进行操作，以构建一个随机突变体文库。分离出526个与碱性磷酸酶有活性基因融合的独立CP9 TnphoA突变体。从这个突变体文库中，检测到8株荚膜缺陷型菌株，发现它们含有单拷贝的TnphoA。随后又获得了16个带有TnphoA插入片段的荚膜缺陷型突变体，这些突变体不具有活性的PhoA融合蛋白。结合最初的8株荚膜缺陷型分离株，我们确定了三个不同XbaI片段上的基因与荚膜产生有关。用噬菌体T4进行的普遍性转导证实，这些插入导致了荚膜的丧失，并且它们是连锁的。这些荚膜缺陷型菌株可用于评估K54荚膜多糖的致病作用。
