유구낭미충의 cathepsin L cDNA 유전자 클로닝과 과발현에 대한 연구

초록

Taenia solium cysticercosis comprised an important neurological disease. Proteolytic enzymes of the helminth parasites play crucial roles in invasion, nutrition and immune evasion in the hosts. We have isolated and sequenced an 1,216-base-pair full-length cDNA coding for a cysteine proteinase(CP) of T. solium metacestode. The cDNA encodes 339 amino acid residues with a calculated molecular weights of 37,573 Da showing a typical domain organization including a signal peptide sequence (18 residues), a pro-peptide(106 residues), and a mature enzyme(215 residues). Sequence alignments revealed that the mature enzyme displayed sequence similarity with cathepsin L of Hydra(59% identity), sparganum(55%), human (58%), rat(57%), F. hepatica(57%) and lobster (54%), and has much less similarities to various types of C. sinensis CP(31-40%), P. westermani CP (41%) and cathepsin B-like CP, such as that of human(25% identity) and rat(28%). Recombinant proteins of the putative mature domain were bacterially expressed and purified by an affinity chromatography. Western blotting results showed that the CP gave significant cross-reactions against sera of patients with fascioliasis, sparganosis, and low levels against those from paragonimiasis and clonorchiasis. Our result suggested strongly that T. solium metacestode cysteine proteinase might play roles in protein metabolism of the parasite itself while showed minimal reactivity with the infection sera.