Atlan D, Gilbert C, Blanc B, Portalier R
Laboratoire de Microbiologie et Génétique Moléculaire, Université Claude Bernard-Lyon I, Villeurbanne, France.
Microbiology (Reading). 1994 Mar;140 ( Pt 3):527-35. doi: 10.1099/00221287-140-3-527.
The proline iminopeptidase (PepIP) of Lactobacillus delbrueckii subsp. bulgaricus is a major peptidase located in the cell envelope. Its structural gene (pepIP) has been cloned into pUC18 and expressed at a very high level in Escherichia coli to give a PepIP activity 15,000-fold higher than that found in L. delbrueckii subsp. bulgaricus. The nucleotide sequence of the pepIP gene revealed an open reading frame of 295 codons encoding a protein with a predicted M(r) of 33,006, which is consistent with the apparent size of the gene product. The amino acid sequence of PepIP shows significant homology with those of other hydrolases involved in the degradation of cyclic compounds. In particular, there is a region which includes an identified catalytic site containing a serine residue and a motif specific for the active sites of prolyloligopeptidases (Gly-X-Ser-X-Gly-Gly). The PepIP opens a new way for supplying cells with proline using the peptides resulting from the proteolytic degradation of caseins.
德氏乳杆菌保加利亚亚种的脯氨酸亚氨基肽酶（PepIP）是一种位于细胞包膜中的主要肽酶。其结构基因（pepIP）已被克隆到pUC18中，并在大肠杆菌中高水平表达，产生的PepIP活性比德氏乳杆菌保加利亚亚种中发现的活性高15000倍。pepIP基因的核苷酸序列揭示了一个295个密码子的开放阅读框，编码一种预测相对分子质量为33006的蛋白质，这与基因产物的表观大小一致。PepIP的氨基酸序列与其他参与环状化合物降解的水解酶的序列具有显著同源性。特别是，有一个区域包含一个已确定的催化位点，该位点含有一个丝氨酸残基和一个脯氨酰寡肽酶活性位点特有的基序（甘氨酸- X -丝氨酸- X -甘氨酸-甘氨酸）。PepIP为利用酪蛋白蛋白水解降解产生的肽为细胞提供脯氨酸开辟了一条新途径。
