Agrobacterium ParA/MinD-like VirC1 spatially coordinates early conjugative DNA transfer reactions
Agrobacterium ParA/MinD-like VirC1 spatially coordinates early conjugative DNA transfer reactions
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DOI：
10.1038/sj.emboj.7601696
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发表时间：
2007-05-16
期刊：
影响因子：
11.4
通讯作者：
Christie, Peter J.
中科院分区：
文献类型：
--
作者：
Atmakuri, Krishnamohan;Cascales, Eric;Christie, Peter J.
根癌农杆菌通过极性VirB/D4 IV型分泌（T4 S）系统易位T-DNA。VirC 1是有效的T-DNA转移所需的因子，具有异常的步行者A和帕拉和MinD ATP酶特征的其他序列基序。在这里，我们表明，VirC 1促进接合T-DNA转移刺激产生多个拷贝每个细胞的T-DNA底物（T-复合物），通过成对的相互作用与加工因子VirD 2松弛酶，VirC 2，和VirD 1。VirC 1还与极性膜相关联，并将T复合物募集到细胞极，这是VirB/D4 T4 S机器组装的位点。VirC 1步行者A突变消除了T-复合物的产生和极性募集，而天然蛋白质募集T-复合物到细胞极独立于其他极性加工因子（VirC 2，VirD 1）或T4 S组分（VirD 4底物受体，VirB通道亚基）。我们建议A.根癌农杆菌已经利用祖细胞帕拉/MinD样ATP酶通过以下方式促进接合DNA转移：（i）在oriT样T-DNA边界序列处成核松弛体组装和（ii）将转移中间体空间定位在细胞极以协调底物-T4 S通道对接。
Agrobacterium tumefaciens translocates T-DNA through a polar VirB/D4 type IV secretion (T4S) system. VirC1, a factor required for efficient T-DNA transfer, bears a deviant Walker A and other sequence motifs characteristic of ParA and MinD ATPases. Here, we show that VirC1 promotes conjugative T-DNA transfer by stimulating generation of multiple copies per cell of the T-DNA substrate (T-complex) through pairwise interactions with the processing factors VirD2 relaxase, VirC2, and VirD1. VirC1 also associates with the polar membrane and recruits T-complexes to cell poles, the site of VirB/D4 T4S machine assembly. VirC1 Walker A mutations abrogate T-complex generation and polar recruitment, whereas the native protein recruits T-complexes to cell poles independently of other polar processing factors (VirC2, VirD1) or T4S components (VirD4 substrate receptor, VirB channel subunits). We propose that A. tumefaciens has appropriated a progenitor ParA/MinD-like ATPase to promote conjugative DNA transfer by: (i) nucleating relaxosome assembly at oriT-like T-DNA border sequences and (ii) spatially positioning the transfer intermediate at the cell pole to coordinate substrate -T4S channel docking.