A self-transmissible, narrow-host-range endogenous plasmid of Rhodobacter sphaeroides 2.4.1: physical structure, incompatibility determinants, origin of replication, and transfer functions.
A self-transmissible, narrow-host-range endogenous plasmid of Rhodobacter sphaeroides 2.4.1: physical structure, incompatibility determinants, origin of replication, and transfer functions.
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球形红细菌 2.4.1 的自传播窄宿主范围内源质粒：物理结构、不相容性决定因素、复制起点和转移功能。
DOI：
10.1128/jb.174.4.1124-1134.1992
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发表时间：
1992
影响因子：
3.2
通讯作者：
Kaplan,S
中科院分区：
文献类型：
--
作者：
Suwanto,A;Kaplan,S
Rhodobacter sphaeroides 2.4.1自然港口五个神秘内生质粒(c·s·佛罗伦·m·沃特金斯和s·卡普兰,质粒11:39-47,1984)。最小的质粒（pRS241e）分子量为42 kb，是一种自传质粒，仅能转移到某些菌株。在无氧的液体介质中，在最佳配合条件下，每个供体的转移频率可高达10（-2）至10（-3）。被称为S因子的pRS241e也被证明具有狭窄的宿主范围，在大肠杆菌、农杆菌和根瘤菌中既不能复制也不能维持。进一步发现，其余4个内源质粒之一pRS241d也具有与s因子相似的传播频率。作为pSUP203的协整基因，S在大肠杆菌中得以维持，为构建S的物理图谱提供了足够的DNA。s因子DNA的逐步亚克隆，结合质粒转移试验，导致oriV (IncA)， IncB和假定的oriT位点的定位和鉴定。含有oriT的427 bp的DNA序列显示出与其他描述的oriT序列的拓扑相似性，包括一个富含a - t的DNA区域，几个直接和反向重复序列，以及推定的整合宿主因子（IHF）结合位点，并被证明具有促进质粒转移的功能。
Rhodobacter sphaeroides 2.4.1 naturally harbors five cryptic endogenous plasmids (C. S. Fornari, M. Watkins, and S. Kaplan, Plasmid 11:39-47, 1984). The smallest plasmid (pRS241e), with a molecular size of 42 kb, was observed to be a self-transmissible plasmid which can transfer only to certain strains of R. sphaeroides. Transfer frequencies can be as high as 10(-2) to 10(-3) per donor under optimal mating conditions in liquid media in the absence of oxygen. pRS241e, designated the S factor, was also shown to possess a narrow host range, failing either to replicate or to be maintained in Escherichia coli, Agrobacterium tumefaciens, and Rhizobium meliloti. It was further revealed that one of the remaining four endogenous plasmids, pRS241d, was also transmissible at a frequency similar to that of the S. factor. As a cointegrate with pSUP203, S was maintained in E. coli, providing sufficient DNA from which a physical map of S could be constructed. Progressive subcloning of S-factor DNA, in conjunction with assays of plasmid transfer, led to the localization and identification of oriV (IncA), IncB, and the putative oriT locus. The DNA sequence of the 427 bp containing oriTs revealed topological similarity to other described oriT sequences, consisting of an A-T-rich DNA region, several direct and inverted repeats, and putative integration host factor (IHF)-binding sites, and was shown to be functional in promoting plasmid transfer.