Autoregulation of Lantibiotic Bovicin HJ50 Biosynthesis by the BovK-BovR Two-Component Signal Transduction System in Streptococcus bovis HJ50
Autoregulation of Lantibiotic Bovicin HJ50 Biosynthesis by the BovK-BovR Two-Component Signal Transduction System in Streptococcus bovis HJ50
复制标题
DOI：
10.1128/aem.01278-10
复制
发表时间：
2010-11
影响因子：
4.4
通讯作者：
Jianqiang Ni;Kunling Teng;Gang Liu;C. Qiao;Liandong Huan;Jin Zhong
中科院分区：
文献类型：
--
作者：
Jianqiang Ni;Kunling Teng;Gang Liu;C. Qiao;Liandong Huan;Jin Zhong
摘要牛链球菌HJ50产生一种类似乳糖素481的33个氨基酸残基的抗生素，命名为Bovicin HJ50。Bovicin HJ50生物合成基因簇中的bovK-bovR被预测为一个双组分信号转导系统，参与感知信号和调节基因表达。BovK或bovR基因的缺失导致了bovicin HJ50产量的减少，表明这两个基因在bovicin HJ50的生物合成中起着重要作用。将外源bovicin HJ50多肽加入到失去bovicin HJ50生产能力的bovM突变体的培养中，并在牛链霉菌HJ50中转录结构基因bova，诱导了bova基因的剂量依赖性转录，表明bovicin HJ50的合成通常是自动调节的。在bovK和bovR突变株中，bovicin HJ50不再诱导Bova的转录，提示BovK-BovR在调控bovicin HJ50生物合成的信号转导中起重要作用。磷酸化实验表明BovK具有自我磷酸化的能力，随后将磷酸化基团转移到下游的BovR蛋白上进行信号转导。电迁移率改变分析(EMSA)和绿色荧光蛋白(GFP)报告基因表达分析表明，BovR与Bova启动子特异结合，表明BovR通过直接结合Bova启动子来调节Bova的表达。综上所述，bovicin HJ50的生物合成是由bovicin HJ50本身诱导的，并受BovK-BovR双组分信号转导系统的调控。
ABSTRACT Streptococcus bovis HJ50 produces a lacticin 481-like 33-amino-acid-residue lantibiotic, designated bovicin HJ50. bovK-bovR in the bovicin HJ50 biosynthetic gene cluster is predicted to be a two-component signal transduction system involved in sensing signals and regulating gene expression. Disruption of bovK or bovR resulted in the abrogation of bovicin HJ50 production, suggesting both genes play important roles in bovicin HJ50 biosynthesis. Addition of exogenous bovicin HJ50 peptide to cultures of a bovM mutant that lost the capability for bovicin HJ50 production and structural gene bovA transcription in S. bovis HJ50 induced dose-dependent transcription of the bovA gene, demonstrating that bovicin HJ50 production was normally autoregulated. The transcription of bovA was no longer induced by bovicin HJ50 in bovK and bovR disruption mutants, suggesting that BovK-BovR plays an essential role in the signal transduction regulating bovicin HJ50 biosynthesis. A phosphorylation assay indicated that BovK has the ability to autophosphorylate and subsequently transfer the phosphoryl group to the downstream BovR protein to carry on signal transduction. Electromobility shift assays (EMSA) and green fluorescent protein (GFP) reporter gene expression assays showed the specific binding of BovR to the bovA promoter, indicating that BovR regulates bovA expression by direct binding between them. Taken together, bovicin HJ50 biosynthesis is induced by bovicin HJ50 itself and regulated via the two-component signal transduction system BovK-BovR.