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首页> 外文期刊>Journal of bacteriology >Molecular Mechanism of Peptide-Specific Pheromone Signaling in Enterococcus faecalis: Functions of Pheromone Receptor TraA and Pheromone-Binding Protein TraC Encoded by Plasmid pPD1
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Molecular Mechanism of Peptide-Specific Pheromone Signaling in Enterococcus faecalis: Functions of Pheromone Receptor TraA and Pheromone-Binding Protein TraC Encoded by Plasmid pPD1

机译：粪肠球菌中肽特异性信息素信号传导的分子机制：质粒pPD1编码的信息素受体TraA和信息素结合蛋白TraC的功能。

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Conjugative transfer of the Enterococcus faecalisplasmid pPD1 is activated by cPD1, one of several peptide sex pheromones secreted by plasmid-free recipient cells, and is blocked by a donor-produced peptide inhibitor, iPD1. Using a tritiated pheromone, [3H]cPD1, we investigated how pPD1-harboring donor cells receive these peptide signals. Donor cells rapidly incorporated [3H]cPD1. The cell extract but not the membrane fraction of the donor strain exhibited significant [3H]cPD1-binding activity. On the basis of these data and those of tracer studies, it was demonstrated that cPD1 was internalized, where it bound to a high-molecular-weight compound. The cell extract of a strain carrying thetraA-bearing multicopy plasmid (pDLHH21) also exhibited high [3H]cPD1-binding activity. A recombinant TraA exhibited a dissociation constant of 0.49 ± 0.08 nM against [3H]cPD1. iPD1 competitively inhibited [3H]cPD1 binding to TraA, whereas pheromones and inhibitors relating to other plasmid systems did not. These results show that TraA is a specific intracellular receptor for cPD1 and that iPD1 acts as an antagonist for TraA. A strain carrying thetraC-bearing multicopy plasmid (pDLES23) exhibited significant [3H]cPD1-binding activity. A strain carryingtraC-disrupted pPD1 (pAM351CM) exhibited lower [3H]cPD1-binding activity as well as lower sensitivity to cPD1 than a wild-type donor strain. Some of the other pheromones and inhibitors inhibited [3H]cPD1 binding to thetraC transformant like cPD1 and iPD1 did. These results show that TraC, as an extracellular less-specific pheromone-binding protein, supports donor cells to receive cPD1.
机译：粪肠球菌质粒pPD1的共转移被cPD1激活，cPD1是无质粒受体细胞分泌的几种肽性信息素之一，并被供体产生的肽抑制剂iPD1阻断。我们使用ti化的信息素[ 3 H] cPD1，研究了携带pPD1的供体细胞如何接收这些肽信号。供体细胞迅速掺入[ 3 H] cPD1。供体菌株的细胞提取物而不是膜部分表现出显着的[ 3 H] cPD1结合活性。根据这些数据和示踪剂研究，证明了cPD1被内在化，并与高分子量化合物结合。携带带有 traA 的多拷贝质粒（pDLHH21）的菌株的细胞提取物也具有高[[sup> 3 H] cPD1结合活性。重组TraA对[ 3 H] cPD1的解离常数为0.49±0.08nM。 iPD1竞争性抑制[ 3 H] cPD1与TraA的结合，而与其他质粒系统有关的信息素和抑制剂则没有。这些结果表明，TraA是cPD1的特定细胞内受体，而iPD1充当TraA的拮抗剂。携带带有 traC 的多拷贝质粒（pDLES23）的菌株表现出显着的[ 3 H] cPD1结合活性。携带 traC 破坏的pPD1（pAM351CM）的菌株与野生型供体菌株相比，显示出较低的[ 3 H] cPD1结合活性以及对cPD1的敏感性。其他一些信息素和抑制剂也像cPD1和iPD1一样抑制[ 3 H] cPD1与 traC 转化子的结合。这些结果表明，TraC作为一种细胞外特异性较低的信息素结合蛋白，支持供体细胞接受cPD1。

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