Paterson E S, Iyer V N
Department of Biology and Institute of Biochemistry, Carleton University, Ottawa, Ontario, Canada.
J Bacteriol. 1992 Jan;174(2):499-507. doi: 10.1128/jb.174.2.499-507.1992.
The oriT region of the conjugative IncN plasmid pCU1 has been localized to a 669-bp sequence extending from pCU1 coordinates 8.48 to 9.15 kb. The nucleotide sequence of this region was determined. The region is AT-rich (69% AT residues), with one 19-bp and one 81-bp sequence containing 79% or more AT residues. Prominent sequence features include one set of thirteen 11-bp direct repeats, a second set of two 14-bp direct repeats, six different inverted repeat sequences ranging from 6 to 10 bp in size, and two sequences showing 12 of 13 nucleotides identical to the consensus integration host factor binding sequence. Specificity between this oriT and mobilization (mob) functions encoded by the N tra system was demonstrated. This specificity is encoded by the region lying clockwise of the BglII site at coordinate 3.3 on the pCU1 map. Two N tra plasmids isolated in the preantibiotic era were unable to mobilize recombinant plasmids carrying the oriT region of pCU1 or to complement transposon Tn5 mutations in the mob region of the closely related plasmid pKM101.
接合型IncN质粒pCU1的oriT区域已定位到一段669碱基对的序列，该序列从pCU1坐标8.48千碱基延伸至9.15千碱基。测定了该区域的核苷酸序列。该区域富含AT（69%为AT残基），有一个19碱基对和一个81碱基对的序列，其中AT残基含量达79%或更高。显著的序列特征包括一组13个11碱基对的正向重复序列、第二组两个14碱基对的正向重复序列、6个大小从6到10碱基对不等的不同反向重复序列，以及两个与共有整合宿主因子结合序列有13个核苷酸中的12个相同的序列。证明了该oriT与N tra系统编码的转移（mob）功能之间的特异性。这种特异性由pCU1图谱上坐标3.3处BglII位点顺时针方向的区域编码。在抗生素时代之前分离的两个N tra质粒无法转移携带pCU1 oriT区域的重组质粒，也无法互补密切相关质粒pKM101的mob区域中的转座子Tn5突变。
