Undecaprenyl pyrophosphate phosphatase confers low-level resistance to bacitracin in Enterococcus faecalis
Undecaprenyl pyrophosphate phosphatase confers low-level resistance to bacitracin in Enterococcus faecalis
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DOI：
10.1093/jac/dkt048
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发表时间：
2013-07-01
影响因子：
5.2
通讯作者：
Cook, Gregory M.
中科院分区：
文献类型：
--
作者：
Shaaly, Aishath;Kalamorz, Falk;Cook, Gregory M.
十一异戊二烯焦磷酸磷酸酶（UppPs）与细菌对杆菌肽的耐药性密切相关，本研究旨在探讨UppPs在粪肠球菌（Enterococcus faecalis）对杆菌肽的低水平耐药性中的作用。粪便基因融合（uppP-lacZ）和5-RACE用于研究uppP表达。将两株菌株的uppP基因失活，并研究突变体的抗菌药物敏感性及其对各种胁迫因子的敏感性。faecalis与大肠杆菌BacA型UppP具有很高的序列同源性，并被预测为具有8个跨膜螺旋的疏水蛋白。uppP-lacZ的表达是组成性的，不受杆菌肽或细胞壁活性抗菌剂的影响。e. faecalis uppP突变体在生长速率、菌落形态和生物膜形成方面没有显著变化。uppP突变体对杆菌肽的敏感性（MIC 36 mg/L）高于同基因野生型（MIC 3248 mg/L）。当uppP在野生型背景下表达时，杆菌肽的MIC增加到128256 mg/L。与野生型相比，uppP突变株对头孢西丁、替考拉宁、万古霉素、庆大霉素、恩诺沙星和d-环丝氨酸的MIC没有改变，对其他应激因子（甘氨酸、溶菌酶、NaCl、SDS、低pH和高pH、氧化应激和乙醇）的敏感性也没有改变。faecalis由BacA型UppP介导。
Undecaprenyl pyrophosphate phosphatases (UppPs) have been implicated in bacitracin resistance in some bacterial genera and the aim of this study was to determine the role of UppPs in mediating low-level bacitracin resistance in Enterococcus faecalis.The uppP gene was identified in the genomes of laboratory (JH2-2) and clinical (V583) strains of E. faecalis. Gene fusions (uppP-lacZ) and 5-RACE were used to study uppP expression. The uppP gene in both strains was inactivated and mutants were studied for antimicrobial susceptibility and their susceptibilities to various stress agents.The UppP protein from E. faecalis showed high sequence identity to the Escherichia coli BacA-type UppP and was predicted to be a hydrophobic protein with eight transmembrane helices. The expression of uppP-lacZ was constitutive and not affected by bacitracin or cell wall-active antimicrobials. E. faecalis uppP mutants showed no significant changes in growth rate, colony morphology and biofilm formation. The uppP mutants exhibited increased susceptibility to bacitracin (MICs36 mg/L) relative to the isogenic wild-type (MICs3248 mg/L). When uppP was expressed in a wild-type background, the MIC of bacitracin increased to 128256 mg/L. The MICs of cefoxitin, teicoplanin, vancomycin, gentamicin, enrofloxacin and d-cycloserine were unaltered in the uppP mutant relative to the wild-type, as were susceptibilities to other stress agents (glycine, lysozyme, NaCl, SDS, low and high pH, oxidative stress and ethanol).The results demonstrate that low-level bacitracin resistance in E. faecalis is mediated by a BacA-type UppP.