Genetic evidence of a coupling role for the TraG protein family in bacterial conjugation
Genetic evidence of a coupling role for the TraG protein family in bacterial conjugation
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DOI：
10.1007/s004380050432
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发表时间：
1997-04-28
期刊：
影响因子：
--
通讯作者：
delaCruz, F
中科院分区：
文献类型：
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作者：
Cabezon, E;Sastre, JI;delaCruz, F
检查了来自六个不同不相容组的接合质粒动员一组可动员质粒的能力。质粒RSF1010、ColE1、ColE3和CloDF13的动员频率变化超过7个数量级，这取决于所使用的辅助接合质粒。CloDF13的动员是独特的，因为它不需要TrwB、TraG或TraD（TraG家族的所有成员）分别通过R388、RP4或F进行动员。CloDF13本身编码一种必需的动员蛋白（MobB），它也是TraG同源物，只需要菌毛形成的基因来源。此外，CloDF13被所有接合质粒有效地动员，表明TraG同源物是质粒动员效率的主要决定因素，与各种松弛体差异地相互作用。先前的结果表明，TraG和TrwB是可互换的动员RSF1010和ColE1的PILW（菌毛系统的IncW质粒），但TraG不能补充的trwB突变体的接合，这表明额外的相互作用之间发生的TrwB和oriT（R388），这不是必不可少的动员。为了进一步验证这一假设，我们分析了在存在替代TraG同系物的情况下，P、W和F药丸对ColE1和RSF1010的动员频率。所获得的结果表明，动员的频率由所使用的特定TraG样蛋白和菌毛系统决定。因此，TraG样蛋白通常不能互换用于动员。因此，我们认为决定不同MOB区域转移频率的因素是TrwB与菌毛和松弛体的差异相互作用。
The ability of conjugative plasmids from six different incompatibility groups to mobilize a set of mobilizable plasmids was examined. The mobilization frequencies of plasmids RSF1010, ColE1, ColE3, and CloDF13 varied over seven orders of magnitude, depending on the helper conjugative plasmid used. Mobilization of CloDF13 was unique in that it did not require TrwB, TraG or TraD (all members of the TraG family) for mobilization by R388, RP4 or F, respectively. CloDF13 itself codes for an essential mobilization protein (MobB) which is also a TraG homolog, only requiring a source of the genes for pilus formation. Besides, CloDF13 was mobilized efficiently by all conjugative plasmids, suggesting that TraG homologs are the primary determinants of the mobilization efficiency of a plasmid, interacting differentially with the various relaxosomes. Previous results indicated that TraG and TrwB were interchangeable for mobilization of RSF1010 and ColE1 by PILW (the pilus system of IncW plasmids) but TraG could not complement conjugation of trwB mutants, suggesting that additional interactions were taking place between TrwB and oriT(R388) that were not essential for mobilization. To further test this hypothesis, we analyzed the mobilization frequencies of ColE1 and RSF1010 by the P, W, and F pill in the presence of alternative TraG homologs. The results obtained indicated that the frequency of mobilization was determined both by the particular TraG-like protein used and by the pilus system. Thus, TraG-like proteins are not generally interchangeable for mobilization. Therefore we suggest that the factors that determine the frequencies of transfer of different MOB regions are the differential interactions of TrwB with pilus and relaxosome.