Multidrug efflux pumps of a periodontopathogenic bacterium. Porphyromonas gingivalis

牙龈卟啉单胞菌是一种革兰氏阴性厌氧菌，是牙周病原菌之一。牙龈假单胞菌有两个多药(异物)转运蛋白，属于耐药结瘤细胞分裂(RND)家族，它是通过BLAST搜索与大肠杆菌AcrAB-TolC外排泵基因同源的开放阅读序列而在牙龈假单胞菌W83基因组中发现的。其中一种，命名为XEP(用于卟啉单胞菌的异源输出物)CAB。排出各种结构无关的药物(阿克利黄素、嘌呤霉素、十二烷基硫酸钠、诺氟沙星、米诺环素等)。在牙龈假单胞菌细胞中，因为这些基因因插入耐药盒而被扰乱的突变体对各种药物更敏感，并在细胞内积累了比亲本菌株ATCC33277更多的吖黄素。主动外排依赖于质子的电化学势，因为在细胞…中积累的吖啶黄素的量在相同程度上加入质子导体(CCCP)后，亲本菌株和突变菌株的产量增加。这表明XepCAB也输出银离子。这是对专性厌氧菌的RND型多药出口菌的第一份报告。这些结果表明，牙龈假单胞菌的多药耐药变异株，例如泵的过度表达，可能会在未来出现。通过对牙龈假单胞菌基因组的计算机分析，推测该细菌具有六个双组分调控系统。其中，fims/fimR和gppX突变对所考察的药物和重金属离子的耐药性没有影响，表明xepCAB的表达不受这两个双组分系统的调控。其中两个副体型(多药和毒药挤出型)泵(PG1117和PG0636)不输出任何药物和所检测的金属离子。RND类出口酶抑制剂MC-207,110似乎能抑制XepCAB的活性。较少

Porphyromonas gingivalis, a gram-negative, obligatery anaerobic rod, is one of the periodontopathogenic bacteria. P.gingivalis has two multidrug (xenobiotic) transporters belonging to the resistance-nodulation-cell division (RND) family, which was found by BLAST search for open reading fames homologous to the AcrAB-TolC efflux pump of Escherichia coli in die P.gingivalis W83 genome (TIGR). One of them, designated as Xep (for xenobiotic exporter of Porphyromonas) CAB. Pumps out various kinds of structurally-unrelated drugs (acriflavine, puromycin, sodium dodecyl sulfate, norfloxacin, minocycline etc.) in P.gingivalis cells, because the mutants in which these genes had been disrupted by the insertion of a drug-resistant cassette were more sensitive to various drugs, and accumulated a larger amount of acriflavine inside the cell, than the parent strain, ATCC33277. The active efflux depends upon an electrochemical potential of proton because the amount of acriflavine accumulated in the cel … More ls of the parent and mutant strains increased by the addition of a proton conductor (CCCP) to the same extent. It is suggested that XepCAB also exports silver ions. This is the first report for the RND-type multidrug exporter of obligate anaerobes. These results suggest that multidrug-resistant variants of P.gingivalis, e.g. with the overexpression of the pump, may appear in the future. It is assumed by computer analysis on the P.gingivalis genome that this bacterium has six two-component regulatory systems. Among them, fimS/fimR and gppX mutations had no effect on the resistance against the drugs and heavy metal ions examined, which indicates that the expression of xepCAB is not regulated by these two-component systems. Two of the MATE (multidrug and toxic coumpound extrusion)-type pumps of P.gingivalis (PG1117 and PG0636) did not export any drugs and metal ions examined. MC-207,110, an inhibitor for RND-type exporters of Pseuclomonas aeniginosa, seems to inhibit the activity of XepCAB. Less