Mobilization of Chimeric oriT Plasmids by F and R100-1: Role of Relaxosome Formation in Defining Plasmid Specificity

摘要: Cleavage at the F plasmid nic site within origin of transfer (oriT) requires F-encoded proteins TraY and TraI host-encoded protein integration host factor in vitro. We confirm that TraY, but not TraM, is required for cleavage vivo. Chimeric plasmids were constructed which contained either entire or R100-1 oriT regions various combinations nic, TraM binding sites, addition to traM gene. The efficiency frequency mobilization assayed presence plasmids. ability these chimeric complement an mutant affect via negative dominance was also measured using assays. In cases where detected, sensitive two-base difference sequence immediately downstream while specific sequence. Plasmid detected only when able bind its cognate sites oriT. High-affinity cis allowed detection efficient mobilization. Taken together, our results suggest stable relaxosomes, consisting TraI, -M, -Y bound are preferentially targeted apparatus (transferosome).