PARTITIONING OF BROAD-HOST-RANGE PLASMID RP4 IS A COMPLEX SYSTEM INVOLVING SITE-SPECIFIC RECOMBINATION
PARTITIONING OF BROAD-HOST-RANGE PLASMID RP4 IS A COMPLEX SYSTEM INVOLVING SITE-SPECIFIC RECOMBINATION
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DOI：
10.1128/jb.172.11.6194-6203.1990
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发表时间：
1990-11-01
影响因子：
3.2
通讯作者：
SCHWAB, H
中科院分区：
文献类型：
--
作者：
GERLITZ, M;HRABAK, O;SCHWAB, H
广泛的主机范围的质粒RP 4编码一个高效的分区系统（PAR），以前被映射在6.2 kb的PstI C片段。基本功能被分配到fiwA和IS 21（IS 8）之间的2.2kb区域。在整个PAR基因座的核苷酸序列数据和体外和体内表达研究的基础上，鉴定了编码9、18和24 kDa多肽的三个不同的基因座。在基因间区发现了一个趋异启动子，该启动子可能与这些基因的转录有关。发现RP 4 par区包括解析质粒二聚体的功能。24-kDa多肽被认为作为解离酶发挥作用，因为其预测的氨基酸显示与Tn 3家族的解离酶序列同源。此外，回文存在于含有趋异启动子的基因间区域类似于Tn 3相关转座子的res位点特异性的重复结构。然而，人们发现，二聚体分辨率本身是不够的稳定，额外的功能，包括其他两个多肽，似乎发挥了重要作用。这些结果表明，RP 4含有一个复杂的稳定系统，涉及在细胞分裂过程中的质粒二聚体的分辨率，从而确保至少一个拷贝的每个子细胞的交付。
The broad-host-range plasmid RP4 encodes a highly efficient partitioning system (par) that was previously mapped within the 6.2-kb PstI C fragment. The essential functions were assigned to a region of 2.2 kb between fiwA and IS21 (IS8). On the basis of the nucleotide sequence data of the entire par locus and of in vitro and in vivo expression studies, three distinct loci encoding polypeptides of 9, 18, and 24 kDa were identified. Evidence for the expression of another polypeptide was found. A putative divergent promoter was localized in an intergenic region and is suggested to be responsible for transcription of these genes. It was found that the RP4 par region includes a function resolving plasmid dimers. The 24-kDa polypeptide is considered to function as a resolvase, since its predicted amino acid shows homology to sequences of resolvases of the Tn3 family. Furthermore, palindromes present in the intergenic region containing the divergent promoter resemble repeat structures specific for res sites of Tn3-related transposons. However, it was found that dimer resolution itself was not sufficient for stabilization; additional functions, including the other two polypeptides, seemed to play an important role. These results suggested that RP4 contains a complex stabilization system involving resolution of plasmid dimers during cell division, thus ensuring the delivery of at least one copy to each daughter cell.