Enterococcus faecium NKR-5-3 produces multiple-bacteriocins, enterocins NKR-5-3A, B, C, D, and Z (Ent53A, Ent53B, Ent53C, Ent53D, and Ent53Z). However, the biosynthetic mechanisms on how their productions are regulated are yet to be fully understood. In silico analysis revealed putative promoters and terminators in the enterocin NKR-5-3ACDZ gene cluster, and the putative direct repeats (5′-ATTTTAGGATA-3′) were conserved upstream of each promoter. Transcriptional analysis by quantitative real-time polymerase chain reaction (PCR) of the biosynthetic genes for the enterocins NKR-5-3 suggested that an inducing peptide (Ent53D) regulates the transcription of the structure genes and corresponding biosynthetic genes of enterocins NKR-5-3, except for Ent53B (a circular bacteriocin), thus consequently regulating their production. Moreover, transcriptional analysis of some knock-out mutants showed that the production of Ent53A, C, D and Z is controlled by a three-component regulatory system (TCS) consisting of Ent53D, EnkR (response regulator), and EnkK (histidine kinase). The production of the circular bacteriocin Ent53B appeared to be independent from this TCS. Nevertheless, disrupting the TCS by deletion of a single component (enkD, enkR and enkK) resulted in a slight increase of enkB transcription and consequently the production of Ent53B, presumably, as an indirect consequence of the increase of available energy to the strain NKR-5-3. Here, we demonstrate the regulatory control of the multiple bacteriocin production of strain NKR-5-3 likely through the TCS consisting of Ent53D, EnkR, and EnkK. The information of the sharing of the regulatory machinery between bacteriocins in strain NKR-5-3 can be useful in its future application such as designing strategies to effectively dispense its multiple bacteriocin arsenal.

屎肠球菌NKR-5-3 产生多种细菌素，肠菌素 NKR-5-3A、B、C、D 和 Z（Ent53A、Ent53B、Ent53C、Ent53D 和 Ent53Z）。然而，其产生如何调节的生物合成机制尚未完全了解。计算机分析揭示了肠素 NKR-5-3ACDZ 基因簇中推定的启动子和终止子，并且推定的同向重复序列 (5'-ATTTTAGGATA-3') 在每个启动子的上游都是保守的。通过实时定量聚合酶链反应 (PCR) 对肠菌素 NKR-5-3 的生物合成基因进行转录分析表明，诱导肽 (Ent53D) 调节肠菌素 NKR-5- 的结构基因和相应的生物合成基因的转录3，除了Ent53B（一种环状细菌素），从而调节它们的产生。此外，一些敲除突变体的转录分析表明，Ent53A、C、D和Z的产生受到由Ent53D、EnkR（反应调节剂）和EnkK（组氨酸激酶）组成的三组分调节系统（TCS）的控制。环状细菌素 Ent53B 的产生似乎独立于该 TCS。然而，通过删除单个组件（ enkD 、 enkR和enkK ）来破坏 TCS 会导致enkB转录略有增加，从而产生 Ent53B，这可能是菌株 NKR 可用能量增加的间接结果。 5-3.在这里，我们证明了菌株 NKR-5-3 的多种细菌素生产的调节控制可能是通过由 Ent53D、EnkR 和 EnkK 组成的 TCS。 NKR-5-3菌株中细菌素之间的调控机制共享的信息对其未来的应用非常有用，例如设计有效分配其多种细菌素库的策略。