Xiao Haijie, Chen Xiuzhu, Chen Meiling, Tang Sha, Zhao Xin, Huan Liandong
Molecular Microbiology Research Center, Institute of Microbiology, Chinese Academy of Sciences, PO Box 2714, Beijing, PR China.
Department of Microbiology, University of California, Riverside, CA 92521, USA.
Microbiology (Reading). 2004 Jan;150(Pt 1):103-108. doi: 10.1099/mic.0.26437-0.
A bacteriocin-producing strain was isolated from raw milk and named Streptococcus bovis HJ50. Like most bacteriocins produced by lactic acid bacteria, bovicin HJ50 showed a narrow range of inhibiting activity. It was sensitive to trypsin, subtilisin and proteinase K. Bovicin HJ50 was extracted by n-propanol and purified by SP Sepharose Fast Flow, followed by Phenyl Superose and Sephadex G-50. Treatment of Micrococcus flavus NCIB8166 with bovicin HJ50 revealed potassium efflux from inside the cell in a concentration-dependent manner. The molecular mass of bovicin HJ50 was determined to be 3428.3 Da. MS analysis of DTT-treated bovicin HJ50 suggested that bovicin HJ50 contains a disulfide bridge. The structural gene of bovicin HJ50 was cloned by nested PCR based on its N-terminal amino acid sequence. Sequence analysis showed that it encodes a 58 aa prepeptide consisting of an N-terminal leader sequence of 25 aa and a C-terminal propeptide domain of 33 aa. Bovicin HJ50 shows similarity to type AII lantibiotics. Chemical modification using an ethanethiol-containing reaction mixture showed that two Thr residues are modified.
从生牛奶中分离出一株产细菌素的菌株，命名为牛链球菌HJ50。与大多数乳酸菌产生的细菌素一样，牛链菌素HJ50的抑制活性范围较窄。它对胰蛋白酶、枯草杆菌蛋白酶和蛋白酶K敏感。牛链菌素HJ50用正丙醇提取，经SP Sepharose Fast Flow纯化，再经Phenyl Superose和Sephadex G - 50纯化。用牛链菌素HJ50处理微黄微球菌NCIB8166后，发现细胞内钾离子以浓度依赖的方式外流。牛链菌素HJ50的分子量测定为3428.3 Da。对用二硫苏糖醇处理的牛链菌素HJ50进行质谱分析表明，牛链菌素HJ50含有一个二硫键。基于其N端氨基酸序列，通过巢式PCR克隆了牛链菌素HJ50的结构基因。序列分析表明，它编码一个由25个氨基酸的N端前导序列和33个氨基酸的C端前肽结构域组成的58个氨基酸的前肽。牛链菌素HJ50与AII型羊毛硫抗生素相似。使用含乙硫醇的反应混合物进行化学修饰表明，有两个苏氨酸残基被修饰。
