Calvez Ségolène, Rincé Alain, Auffray Yanick, Prévost Hervé, Drider Djamel
UMR-INRA 1014 SECALIM, ENITIAA, Rue de la Géraudière, BP 82225, Nantes Cedex 3, France.
Laboratoire de Microbiologie de l'Environnement, EA 956, USC INRA 2017, IRBA, Université de Caen, Caen Cedex, France.
Microbiology (Reading). 2007 May;153(Pt 5):1609-1618. doi: 10.1099/mic.0.2006/004812-0.
It has been suggested that resistance to class IIa bacteriocins occurs at either a low or a high level. In listerial strains, low-level resistance (2-4-fold) to class IIa bacteriocins is attributed to alterations in membrane lipid composition. In Listeria monocytogenes and Enterococcus faecalis, high-level resistance (1000-fold) correlates with inactivation of the mptACD operon, which encodes the EII(Man)(t) mannose permease of the phosphotransferase system (PTS). Previous studies reported that in L. monocytogenes, high-level resistance involved the sigma(54) factor and the ManR activator. In this investigation, three genes associated with the resistance of Ent. faecalis JH2-2 to divercin V41, a pediocin-like bacteriocin from Carnobacterium divergens V41, were clearly identified by screening an insertional mutant library of Ent. faecalis JH2-2. These genes correspond to the well-known rpoN gene, which encodes sigma(54) factor, and to genes encoding a glycerophosphoryl diester phosphodiesterase (GlpQ) and a protein with a putative phosphodiesterase function (PDE). Resistance of the three mutants defective in the aforementioned genes appeared to be graduated: the rpoN mutant was more resistant than the glpQ mutant, which was more resistant than the pde mutant. Moreover, this resistance was specific to class IIa bacteriocins.
有人提出，对IIa类细菌素的抗性存在低水平或高水平两种情况。在李斯特菌菌株中，对IIa类细菌素的低水平抗性（2 - 4倍）归因于膜脂质组成的改变。在单核细胞增生李斯特菌和粪肠球菌中，高水平抗性（1000倍）与mptACD操纵子的失活相关，该操纵子编码磷酸转移酶系统（PTS）的EII(Man)(t)甘露糖通透酶。先前的研究报道，在单核细胞增生李斯特菌中，高水平抗性涉及sigma(54)因子和ManR激活剂。在本研究中，通过筛选粪肠球菌JH2 - 2的插入突变体文库，明确鉴定出了与粪肠球菌JH2 - 2对来自分歧肉杆菌V41的一种类片球菌素——双歧菌素V41的抗性相关的三个基因。这些基因对应于著名的rpoN基因，其编码sigma(54)因子，以及编码甘油磷酸二酯磷酸二酯酶（GlpQ）和具有推定磷酸二酯酶功能的蛋白质（PDE）的基因。上述基因有缺陷的三个突变体的抗性似乎呈梯度变化：rpoN突变体比glpQ突变体更具抗性，而glpQ突变体比pde突变体更具抗性。此外，这种抗性对IIa类细菌素具有特异性。
