Shen_1999_Sheng.Wu.Hua.Xue.Yu.Sheng.Wu.Wu.Li.Xue.Bao.(Shanghai)_31_567

Prolyl endopeptidase activity was found in Aeromonas punctata subsp. Punctata. The genomic DNA was partially digested with EcoRI and the recovered 8-16 kb DNA fragments were inserted into the EcoRI site of plasmid pUC19, and were transformated into Escherichia coli DH5alpha. The resulted clones were screened by using Benzyloxycarbonyl-Gly-Pro-beta-naphthylamide, the specific substrate of prolyl endopeptidase and a positive clone was obtained. The 12 kb insertion fragment of recombinant plasmid was digested with HincII and subcloned. The PEP gene was found in the 3.5 kb HincII/EcoRI fragment. Nucleotide sequence of the gene was completely sequenced by Auto Sequencer. The complete gene consisted of 2 073 bp corresponding to 690 amino acid residues with a calculated molecular weight of 76 467 Da. The amino acid sequence was 92.3% 53.2% 33.5% 33.2% and 20.5% homologous to those of Aeromonas hydrophila, Flavobacterium meningosepticum, porcine brain, human lymphocytes and Pyrococcus furiosus respectively. From a survey of sequence homology with other members of the prolyl endopeptidase family, the amino acid residues involved in the catalytic triad were deduced to be Ser(538) Asp(622) and His(657).