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首页> 外文期刊>Journal of bacteriology >Regulation of transfer of the Enterococcus faecalis pheromone-responding plasmid pAD1: temperature-sensitive transfer mutants and identification of a new regulatory determinant, traD.
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Regulation of transfer of the Enterococcus faecalis pheromone-responding plasmid pAD1: temperature-sensitive transfer mutants and identification of a new regulatory determinant, traD.

机译：粪肠球菌信息素响应质粒pAD1的转移调控：温度敏感的转移突变体和新的调控决定因子traD的鉴定。

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The enterococcal, conjugative, cytolysin plasmid pAD1 confers a mating response to the peptide sex pheromone cAD1 secreted by plasmid-free strains of Enterococcus faecalis. Cells carrying pAM714, a pAD1::Tn917 derivative with wild-type conjugation properties, were mutagenized with ethyl methanesulfonate to obtain variants that were induced (in the absence of pheromone) to transfer plasmid DNA upon shifting from 32 to 42 degrees C. Of 31 such mutants generated, the results of analyses of 7 are presented in detail. All seven strains were thermosensitive in the E. faecalis host FA2-2; colony morphology, clumping, and DNA transfer correlated well with each other at the two temperatures. In the nonisogenic host E. faecalis OG1X, however, only one derivative (pAM2725) exhibited correlation of all three traits at both temperatures. Three (pAM2700, pAM2703, and pAM2717) clumped and had colonies characteristic of pheromone-induced cells at 32 degrees C but transferred plasmid DNA at a higher frequency only at the elevated temperature. The other three (pAM2708, pAM2709, and pAM2712) were derepressed at both temperatures for all three characteristics. Four of the mutations, including that of pAM2725, mapped within the traA determinant, whereas two mapped identically in a previously unnoted open reading frame (designated traD) putatively encoding a short (23-amino-acid) peptide downstream of the inhibitor peptide determinant iad and in the opposite orientation. One mutant could not be located in the regions sequenced. Studies showed that the traA and traD mutations could be complemented in trans with a DNA fragment carrying the corresponding regions.
机译：肠球菌结合型溶血素质粒pAD1赋予对粪肠球菌无质粒菌株分泌的肽性信息素cAD1的交配反应。用甲磺酸乙酯诱变携带pAM714（具有野生型缀合特性的pAD1 :: Tn917衍生物）的细胞，将其诱变（在不存在信息素的情况下），将其从32℃转变为42℃后转移质粒DNA。31产生此类突变体后，将详细介绍7种分析结果。在粪肠球菌宿主FA2-2中，所有七个菌株都是热敏感的。在这两个温度下，菌落的形态，结块和DNA转移相互之间具有很好的相关性。然而，在非等基因宿主粪肠球菌OG1X中，只有一个衍生物（pAM2725）在两个温度下都表现出所有三个性状的相关性。三个（pAM2700，pAM2703和pAM2717）结块，在32摄氏度时具有信息素诱导的细胞的集落特征，但仅在升高的温度下才以较高的频率转移质粒DNA。对于这三个特性，在这两个温度下都将其他三个（pAM2708，pAM2709和pAM2712）降压。四个突变（包括pAM2725的突变）在traA决定簇内定位，而两个突变在以前未发现的开放阅读框（指定为traD）中相同地定位，假定编码下游抑制肽决定簇iad的短（23个氨基酸）肽段方向相反。一个突变体不能位于测序区域中。研究表明，traA和traD突变可通过带有相应区域的DNA片段反式互补。

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