l'Anson K J, Movahedi S, Griffin H G, Gasson M J, Mulholland F
Institute of Food Research, Norwich Laboratory, Colney, UK.
Microbiology (Reading). 1995 Nov;141 ( Pt 11):2873-81. doi: 10.1099/13500872-141-11-2873.
Degenerate PCR primers were designed from the N-terminal amino acid sequence of a glutamyl aminopeptidase (PepA) from Lactococcus lactis. These primers were used to screen a lambda library for clones containing the gene (pepA) encoding PepA. The DNA sequence of a 2.1 kb fragment containing pepA was determined. The sequence revealed the presence of one complete and two incomplete open reading frames (ORFs). The complete ORF encodes a putative protein of 353 amino acids with a predicted N-terminal sequence identical to that determined for purified PepA. The pepA gene was subcloned on an Escherichia coli plasmid vector and production of active PepA was confirmed by means of a zymogram. Mutants of L. lactis in which the pepA gene was inactivated grew to normal cell densities in milk but exhibited a reduced growth rate during the exponential phase. Thus whilst PepA is required for optimal growth it is not essential.
根据乳酸乳球菌谷氨酰胺氨基肽酶（PepA）的N端氨基酸序列设计了简并PCR引物。这些引物用于筛选λ文库，以寻找含有编码PepA的基因（pepA）的克隆。测定了包含pepA的2.1 kb片段的DNA序列。该序列显示存在一个完整的和两个不完整的开放阅读框（ORF）。完整的ORF编码一个推定的由353个氨基酸组成的蛋白质，其预测的N端序列与纯化的PepA的N端序列相同。将pepA基因亚克隆到大肠杆菌质粒载体上，并通过酶谱法证实了活性PepA的产生。pepA基因失活的乳酸乳球菌突变体在牛奶中生长至正常细胞密度，但在指数生长期生长速率降低。因此，虽然PepA是最佳生长所必需的，但不是必不可少的。
