Novel macrolide-specific ABC-type efflux transporter in Escherichia coli
Novel macrolide-specific ABC-type efflux transporter in Escherichia coli
复制标题
DOI：
10.1128/jb.183.19.5639-5644.2001
复制
发表时间：
2001-10-01
影响因子：
3.2
通讯作者：
Yamaguchi, A
中科院分区：
文献类型：
--
作者：
Kobayashi, N;Nishino, K;Yamaguchi, A
在大肠杆菌基因组中，5个推定的开放阅读框（ORF）簇mdlAB、ybjYZ、yddA、yojHI和yhiH已被假定为ABC药物外排转运蛋白的可能基因（I. T. Paulsen，M. K. Sliwinski和M. H.小赛尔，J. Mol. 277：573-592，1998）。我们！我们！将所有这些ORF克隆到多拷贝质粒中，并研究了缺乏组成型多药外排转运蛋白基因acrAB的药物超敏宿主细胞的耐药性。其中只有ybjYZ产生了显著的红霉素抗性，并显著降低了[C-14]红霉素的积累。因此，ybjYZ更名为macAB（大环内酯特异性ABC型外排载体）。同时携带macA和-B基因的原生质体对由14-和15-元内酯组成的大环内酯类药物具有抗性，但对16-元内酯没有抗性或抗性较弱。这两个基因都不能单独产生抗性。DNA序列表明MacB是一个完整的膜蛋白，具有四个跨膜片段和一个核苷酸结合结构域，而MacA属于膜融合蛋白（MFP）家族，在其N末端具有信号样序列。组氨酸标记的蛋白的表达证实，MacB是一个完整的膜蛋白和MacA是一个外周膜蛋白。此外，MacAB的功能需要TolC，其方式类似于大肠杆菌中大多数MFP-dependent转运蛋白的功能。杆菌因此，MacB是一种新的ABC型大环内酯外排转运蛋白，其通过与MFP MacA和多功能外膜通道TolC合作发挥作用。这是第一例实验确定的ABC抗生素外排转运蛋白在革兰氏阴性菌。
In the Escherichia coli genome, five putative open reading frame (ORF) clusters, mdlAB, ybjYZ, yddA, yojHI, and yhiH, have been assumed to be possible genes for ABC drug efflux transporters (I. T. Paulsen, M. K. Sliwinski, and M. H. Saier, Jr., J. Mol. Biol. 277:573-592, 1998). We! cloned all of these ORFs in multicopy plasmids and investigated the drug resistance of drug-supersensitive host cells lacking constitutive multidrug efflux transporter genes acrAB. Among them, only ybjYZ gave significant erythromycin resistance and significantly decreased the accumulation of [C-14] erythromycin. Therefore, ybjYZ was renamed macAB (macrolide-specific ABC-type efflux carrier). Plasmids carrying both the macA and -B genes conferred resistance against macrolides composed of 14- and 15-membered lactones but no or weak resistance against 16-membered ones. Neither of the two genes produced resistance alone. The DNA sequence suggests that MacB is an integral membrane protein with four transmembrane segments and one nucleotide-binding domain, while MacA belongs to a membrane fusion protein (MFP) family with a signal-like sequence at its N terminus. The expression of the histidine-tagged proteins confirmed that MacB is an integral membrane protein and MacA is a peripheral membrane protein. In addition, MacAB required TolC for its function in a way similar to that of most of the MFP-dependent transporters in E. coli. MacB is thus a novel ABC-type macrolide efflux transporter which functions by cooperating with the MFP MacA and the multifunctional outer membrane channel TolC. This is the first case of an experimentally identified ABC antibiotic efflux transporter in gram-negative organisms.