Molecular characterization of a partial sequence encoding a novel Schistosoma mansoni serine protease

• Published in: Parasitology 1997-10, Vol.115 (4), p.395-402
• Main Authors: COCUDE, C., PIERROT, C., CETRE, C., GODIN, C., CAPRON, A., KHALIFE, J.
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; Antibodies, Helminth; Base Sequence; Biochemistry. Physiology. Immunology. Molecular biology; Biological and medical sciences; Cloning, Molecular; Fundamental and applied biological sciences. Psychology; Helminth Proteins - genetics; Immunoblotting; Invertebrates; kallikrein-like protease; Kallikreins - genetics; Molecular Sequence Data; Nemathelminthia. Plathelmintha; Physiology. Development; Polymerase Chain Reaction; Precipitin Tests; RNA, Helminth - isolation & purification; RNA, Messenger - isolation & purification; Schistosoma mansoni; Schistosoma mansoni - enzymology; Schistosoma mansoni - genetics; Sequence Analysis, DNA; Sequence Homology, Amino Acid; Serine Endopeptidases - genetics; Serine Endopeptidases - immunology; serine protease
• ISSN: 0031-1820; 1469-8161
• DOI: 10.1017/S0031182097001546

A PCR strategy using degenerate oligonucleotide primers based upon consensus sequences of the active site of serine proteases yielded a 467 bp fragment from genomic DNA from Schistosoma mansoni cercariae. The sequence presented a continuous open reading frame and the deduced amino acid sequence (156 aa) presented homologies with various serine proteases, in particular the highest percentage identity was observed with a mammalian plasma kallikrein. The expression of this serine protease was studied first at the mRNA level and it was only detected by RT-PCR in cercariae and in adult worms. At the protein level we were able to detect it by Western blotting and by using antigen extracts from metabolically radio-isotope labelled worms. The absence of any positive signal in Northern blot and the detection of the protein suggest that the mRNA has a very short half-life, however the protein may be accumulated in the parasite. The significance of identity with mammalian kallikrein was confirmed by cross-immunoreactivity with a native porcine pancreatic kallikrein. However, no cross-reactivity was observed with S. mansoni elastase, another serine protease. Thus, we suggest that the serine protease described in this paper is a kallikrein-like protease.