Dale E M, Binns A N, Ward J E
Department of Biology, University of Pennsylvania, Philadelphia 19104-6018.
J Bacteriol. 1993 Feb;175(3):887-91. doi: 10.1128/jb.175.3.887-891.1993.
Transfer of the T-DNA from the Ti plasmid of Agrobacterium tumefaciens into plant cells involves movement of a single-stranded DNA-protein intermediate across several membrane and cell wall barriers. The 11 VirB proteins encoded by the Ti plasmid are hypothesized to form at least part of a membrane-localized T-DNA transport apparatus. Although available genetic and biochemical analyses support this hypothesis, detailed study of this transport apparatus is hindered by the fact that most available mutations in the virB operon are in the form of transposon insertions that have polar effects. In this study we constructed a transposon, Tn5virB, that can be used to generate nonpolar insertions in operons of A. tumefaciens and used it to demonstrate that virB8 is an essential virulence gene.
根癌土壤杆菌Ti质粒上的T-DNA转移至植物细胞，涉及单链DNA-蛋白质中间体跨越多个膜和细胞壁屏障的移动。Ti质粒编码的11种VirB蛋白被推测至少构成膜定位T-DNA转运装置的一部分。尽管现有的遗传和生化分析支持这一假说，但由于virB操纵子中大多数可用突变都是具有极性效应的转座子插入形式，这一转运装置的详细研究受到阻碍。在本研究中，我们构建了一个转座子Tn5virB，可用于在根癌土壤杆菌操纵子中产生非极性插入，并利用它证明virB8是一个必需的毒力基因。
