Qiao M, Immonen T, Koponen O, Saris P E
Institute of Biotechnology, University of Helsinki, Finland.
FEMS Microbiol Lett. 1995 Aug 15;131(1):75-80. doi: 10.1016/0378-1097(95)00238-z.
Lactococcus lactis cells secreting the lantibiotic nisin, commercially used for food preservation, must protect their cell membrane against the pore-forming activity of extracellular nisin. The nisI gene product has been suggested to be a lipoprotein, which due to the location on the extracellular surface would be an ideal candidate for an immunity protein. In vivo labelling of NisI from L. lactis N8 expressed in Escherichia coli proved that NisI is a lipoprotein. Expression of nisI in the nisin-sensitive L. lactis MG1614 strain resulted in immunologically active protein on the cytoplasmic membrane in comparable amounts to the immune strain L. lactis N8, but only to slightly increased nisin immunity, suggesting that additional proteins are needed for full immunity.
分泌用于食品保鲜的乳链菌肽的乳酸乳球菌细胞，必须保护其细胞膜免受细胞外乳链菌肽的成孔活性影响。nisI基因产物被认为是一种脂蛋白，由于其位于细胞外表面，将是免疫蛋白的理想候选者。对在大肠杆菌中表达的乳酸乳球菌N8的NisI进行体内标记，证明NisI是一种脂蛋白。在对乳链菌肽敏感的乳酸乳球菌MG1614菌株中表达nisI，导致细胞质膜上出现具有免疫活性的蛋白质，其含量与免疫菌株乳酸乳球菌N8相当，但仅使乳链菌肽免疫力略有增加，这表明完全免疫还需要其他蛋白质。
