β-Lactam Selectivity of Multidrug Transporters AcrB and AcrD Resides in the Proximal Binding Pocket
β-Lactam Selectivity of Multidrug Transporters AcrB and AcrD Resides in the Proximal Binding Pocket
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DOI：
10.1074/jbc.m114.547794
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发表时间：
2014-04-11
影响因子：
4.8
通讯作者：
Murakami, Satoshi
中科院分区：
文献类型：
--
作者：
Kobayashi, Naoki;Tamura, Norihisa;Murakami, Satoshi
背景：细菌多药转运蛋白AcrB和AcrD输出内酰胺类抗生素。结果：近端结合口袋中的带电残基在β-内酰胺选择性中起着至关重要的作用。结论：近端囊袋在进入底物转运途径的位点处充当底物选择过滤器。意义：我们对抗生素识别的分子机制的理解对于克服耐药性至关重要。内酰胺类抗生素是预防和治疗细菌感染的主流抗生素。AcrA-AcrD-TolC多药外排系统比同源AcrA-AcrB-TolC系统赋予大肠杆菌对临床相关阴离子内酰胺抗生素更强的抗性。使用广泛的嵌合分析和定点诱变的组合，我们寻找的残基，确定的差异-内酰胺特异性之间的AcrB和AcrD。我们确定了三个关键的残基在近端（或访问）底物结合口袋。AcrD（Q569 R，I626 R和E673 G）中的这些残基在AcrB中的同时替换将AcrD的β-内酰胺特异性转移到AcrB。我们的研究结果表明，第一次在-内酰胺特异性AcrB和AcrD之间的差异涉及到近端结合口袋中的残留物的抗生素的相互作用。
Background: Bacterial multidrug transporters AcrB and AcrD export -lactam antibiotics. Results: Charged residues in the proximal binding pocket play a crucial role in -lactam selectivity. Conclusion: Proximal pocket acts as a substrate selection filter at the site of entry into the substrate translocation pathway. Significance: Our understanding of molecular mechanisms of antibiotic recognition is essential for overcoming drug resistance.-Lactams are mainstream antibiotics that are indicated for the prophylaxis and treatment of bacterial infections. The AcrA-AcrD-TolC multidrug efflux system confers much stronger resistance on Escherichia coli to clinically relevant anionic -lactam antibiotics than the homologous AcrA-AcrB-TolC system. Using an extensive combination of chimeric analysis and site-directed mutagenesis, we searched for residues that determine the difference in -lactam specificity between AcrB and AcrD. We identified three crucial residues at the proximal (or access) substrate binding pocket. The simultaneous replacement of these residues in AcrB by those in AcrD (Q569R, I626R, and E673G) transferred the -lactam specificity of AcrD to AcrB. Our findings indicate for the first time that the difference in -lactam specificity between AcrB and AcrD relates to interactions of the antibiotic with residues in the proximal binding pocket.