Laboratory of Microbial Gene Technology and Food Microbiology, Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Norway.
BMC Microbiol. 2010 Aug 25;10:224. doi: 10.1186/1471-2180-10-224.
The class IIa bacteriocin, pediocin PA-1, has clear potential as food preservative and in the medical field to be used against Gram negative pathogen species as Enterococcus faecalis and Listeria monocytogenes. Resistance towards class IIa bacteriocins appear in laboratory and characterization of these phenotypes is important for their application. To gain insight into bacteriocin resistance we studied mutants of E. faecalis V583 resistant to pediocin PA-1 by use of transcriptomic analyses.
Mutants of E. faecalis V583 resistant to pediocin PA-1 were isolated, and their gene expression profiles were analyzed and compared to the wild type using whole-genome microarray. Significantly altered transcription was detected from about 200 genes; most of them encoding proteins involved in energy metabolism and transport. Glycolytic genes were down-regulated in the mutants, but most of the genes showing differential expression were up-regulated. The data indicate that the mutants were relieved from glucose repression and putative catabolic responsive elements (cre) could be identified in the upstream regions of 70% of the differentially expressed genes. Bacteriocin resistance was caused by reduced expression of the mpt operon encoding the mannose-specific phosphoenolpyruvate:carbohydrate phosphotransferase system (PTS), and the same transcriptional changes were seen in a mptD-inactivated mutant. This mutant also had decreased transcription of the whole mpt operon, showing that the PTS is involved in its own transcriptional regulation.
Our data confirm the important role of mannose PTS in class IIa bacteriocin sensitivity and we demonstrate its importance involving global carbon catabolite control.
IIa 型细菌素肠球菌素 PA-1 具有明显的作为食品防腐剂的潜力，并且可以在医学领域中用于对抗革兰氏阴性病原体物种，如粪肠球菌和李斯特菌单核细胞增生症。在实验室中出现了对 IIa 型细菌素的抗性，对这些表型进行特征描述对于它们的应用非常重要。为了深入了解细菌素抗性，我们使用转录组分析研究了对肠球菌素 PA-1 具有抗性的粪肠球菌 V583 的突变体。
分离出对肠球菌素 PA-1 具有抗性的粪肠球菌 V583 突变体，并使用全基因组微阵列分析比较其与野生型的基因表达谱。检测到约 200 个基因的转录发生显著变化；其中大多数编码涉及能量代谢和运输的蛋白质。突变体中的糖酵解基因下调，但显示差异表达的大多数基因上调。数据表明，突变体摆脱了葡萄糖抑制，并且可以在 70%的差异表达基因的上游区域识别出假定的分解代谢响应元件（cre）。细菌素抗性是由编码甘露糖特异性磷酸烯醇丙酮酸：碳水化合物磷酸转移酶系统（PTS）的 mpt 操纵子表达减少引起的，在 mptD 失活突变体中也观察到相同的转录变化。该突变体还表现出整个 mpt 操纵子的转录减少，表明 PTS 参与其自身的转录调控。
我们的数据证实了 mannose PTS 在 IIa 型细菌素敏感性中的重要作用，并且我们证明了其在全局碳分解代谢物控制中的重要性。
