CHARACTERIZATION OF THE CELL WALL-BOUND PROTEINASE OF LACTOBACILLUS-CASEI HN14
CHARACTERIZATION OF THE CELL WALL-BOUND PROTEINASE OF LACTOBACILLUS-CASEI HN14
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DOI：
10.1128/aem.57.6.1753-1757.1991
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发表时间：
1991-06-01
影响因子：
4.4
通讯作者：
TOPISIROVIC, L
中科院分区：
文献类型：
--
作者：
KOJIC, M;FIRA, D;TOPISIROVIC, L
干酪乳杆菌HN 14是从自制奶酪中分离出来的，它产生一种细胞外的、细胞壁结合的蛋白酶。HN 14蛋白酶可通过在无Ca 2+缓冲液中洗涤细胞而从细胞包膜中除去。粗蛋白酶提取物的活性被苯甲基磺酰氟抑制，表明该酶是丝氨酸型蛋白酶。考虑到底物特异性，HN 14蛋白酶类似于乳球菌PI型酶，因为它仅水解β-酪蛋白。干酪乳杆菌HN 14似乎是无质粒的，这表明蛋白酶基因位于染色体上。该菌株的染色体DNA与DNA探针Q1（其含有prtM基因的片段）和Q6和Q92（其含有prtP基因的片段）杂交;所有三种探针均源自乳酸乳球菌乳酸亚种的蛋白酶基因区域。Cremoris Wg2.在杂交实验的基础上，构建了干酪乳杆菌HN 14蛋白酶区的限制性内切酶图谱。比较干酪乳杆菌HN 14蛋白酶基因区和迄今为止研究的乳球菌蛋白酶基因区的限制性内切酶图谱，表明它们高度相似。
Lactobacillus casei HN14, which was isolated from homemade cheese, produces an extracellular, cell wall-bound proteinase. The HN14 proteinase can be removed from the cell envelope by washing the cells in a Ca2+-free buffer. The activity of the crude proteinase extract is inhibited by phenylmethylsulfonyl fluoride, showing that the enzyme is a serine-type proteinase. Considering the substrate specificity, the HN14 proteinase is similar to the lactococcal PI-type enzyme, since it hydrolyzes beta-casein only. Lactobacillus casei HN14 appeared to be plasmid free, which suggests that the proteinase gene is chromosomally located. Chromosomal DNA of this strain hybridizes with DNA probes Q1 (which contains a fragment of the prtM gene) and Q6 and Q92 (which contain fragments of the prtP gene); all three probes originated from the proteinase gene region of Lactococcus lactis subsp. cremoris Wg2. A restriction enzyme map of the proteinase region of Lactobacillus casei HN14 was constructed on the basis of hybridization experiments. Comparison of the restriction enzyme maps of the Lactobacillus casei HN14 proteinase gene region and those of lactococcal proteinase gene regions studied so far indicates that they are highly similar.