Quorum sensing and multidrug transporters in Escherichia coli
Quorum sensing and multidrug transporters in Escherichia coli
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DOI：
10.1073/pnas.0502890102
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发表时间：
2006-02-14
影响因子：
11.1
通讯作者：
Zechiedrich, EL
中科院分区：
文献类型：
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作者：
Yang, S;Lopez, CR;Zechiedrich, EL
以前，我们发现，群体感应转录因子SdiA上调AcrAB。其他人发现4-喹诺酮是铜绿假单胞菌中的群体感应信号。在大肠杆菌中，至少有三种多药转运蛋白（AcrAB/ToIC、MdfA和NorE）分泌氟喹诺酮类药物。在这里，我们表明，Δ acrAB，toIC 210，或Δ norE突变体具有相同的生长速率WT细胞在指数期，但生长到更高的细胞密度在稳定期。任一泵的过度生产导致细胞达到较低的密度。mdfA没有效果。来自过表达acrAB的细胞的条件培养基（CM）比来自WT细胞的CM更抑制细胞生长。来自泵突变细胞的CM抑制细胞生长的程度低于来自WT细胞的CM。这些结果不受合成群体感应信号自诱导物2（AI-2）的luxS的缺失的影响。编码稳定期σ因子的rpoS基因的表达在过表达acrAB的细胞中诱导较早，在acrAB突变细胞中诱导较晚。这些结果支持一个模型，其中AcrAB/ToIC和NorE的自然功能是输出细胞间通信的信号。通过泵输出的药物可能类似于正常分泌的通讯分子。
Previously, we found that the quorum sensing transcription factor SdiA up-regulates AcrAB. Others found that a 4-quinolone was a quorum-sensing signal in Pseudomonas aeruginosa. In Escherichia coli, there are at least three multidrug transporters (AcrAB/ToIC, MdfA, and NorE) that exude fluoroquinolones. Here, we show that Delta acrAB, toIC210, or Delta norE mutants have the same growth rate as WT cells in exponential phase but grow to higher cell density in stationary phase. Overproduction of either pump caused cells to reach lower density. mdfA had no effect. Conditioned medium (CM) from cells overexpressing acrAB represses cell growth more than CM from WT cells. CM from pump mutant cells represses cell growth less than CM from WT cells. These results were not affected by the deletion of luxS, which synthesizes the quorum-sensing signal autoinducer 2 (AI-2). Expression of the rpoS gene encoding the stationary phase sigma factor is induced earlier in cells overexpressing acrAB and later in acrAB mutant cells. These results support a model in which a natural function of AcrAB/ToIC and NorE is to export signals for cell-cell communication. Drugs exported by pumps may resemble communication molecules normally exuded.