ParI, an orphan ParA family protein from Pseudomonas putida KT2440-specific genomic island, interferes with the partition system of IncP-7 plasmids.
ParI, an orphan ParA family protein from Pseudomonas putida KT2440-specific genomic island, interferes with the partition system of IncP-7 plasmids.
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DOI：
10.1111/j.1462-2920.2012.02861.x
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发表时间：
2012-11
影响因子：
5.1
通讯作者：
M. Miyakoshi;M. Shintani;K. Inoue;Tsuguno Terabayashi;Fumiya Sai;M. Ohkuma;H. Nojiri;Y. Nagata;M. Tsuda
中科院分区：
文献类型：
--
作者：
M. Miyakoshi;M. Shintani;K. Inoue;Tsuguno Terabayashi;Fumiya Sai;M. Ohkuma;H. Nojiri;Y. Nagata;M. Tsuda
恶臭假单胞菌KT2440是一种理想的土壤细菌，通过招募各种分解代谢质粒来扩大可降解化合物的范围。在我们对IncP-7分解代谢质粒pCAR1、pDK1和pWW53宿主范围的研究过程中，我们发现由复制和分裂位点组成的IncP-7微型质粒在原型IncP-9质粒pWW0的真实宿主KT2440中异常不稳定。本研究发现，ParI是kt2440特异性隐性基因组岛编码的质粒分配蛋白ParA家族的同源物，是维持IncP-7质粒的负宿主因子。ParI的异位表达使微质粒失稳，失稳率与ParB在着丝性parS区结合位点的拷贝数有关。ParI保守的atp酶结构域的突变消除了微质粒的不稳定性。此外，ParI破坏了携带分割缺陷parA突变的小质粒衍生物的稳定性，但未能影响在假定的精氨酸指中携带parB突变的小质粒衍生物的稳定性。总之，这些结果表明ParI干扰了IncP-7质粒分割系统。本研究将典型分割介导的质粒不亲和性扩展到异质性移动遗传元件之外，即质粒和基因组岛之间的不亲和性。
Pseudomonas putida KT2440 is an ideal soil bacterium for expanding the range of degradable compounds via the recruitment of various catabolic plasmids. In the course of our investigation of the host range of IncP-7 catabolic plasmids pCAR1, pDK1 and pWW53, we found that the IncP-7 miniplasmids composed of replication and partition loci were exceptionally unstable in KT2440, which is the authentic host of the archetypal IncP-9 plasmid pWW0. This study identified ParI, a homologue of ParA family of plasmid partitioning proteins encoded on the KT2440-specific cryptic genomic island, as a negative host factor for the maintenance of IncP-7 plasmids. The miniplasmids were destabilized by ectopic expression of ParI, and the loss rate correlated with the copy number of ParB binding sites in the centromeric parS region. Mutations in the conserved ATPase domains of ParI abolished destabilization of miniplasmids. Furthermore, ParI destabilized miniplasmid derivatives carrying the partition-deficient parA mutations but failed to impact the stability of miniplasmid derivatives with parB mutations in the putative arginine finger. Altogether, these results indicate that ParI interferes with the IncP-7 plasmid partition system. This study extends canonical partition-mediated incompatibility of plasmids beyond heterogeneous mobile genetic elements, namely incompatibility between plasmid and genomic island.