Cloning and homology modeling of a serine protease gene (PrC) from the nematophagous fungus Clonostachys rosea

Abstract

The nematophagous fungus Clonostachys rosea can parasitize nematodes as well as insects and several fungi. Proteases play critical roles during infection and are considered important virulence factors in these fungi. In this study, a cuticle-degrading serine protease gene (PrC) was cloned for the first time from C. rosea. The gene contained three introns and four exons and encodes a polypeptide of 386 amino acid residues. The mature protein is 277 amino acid residues long and contains a conserved motif shared by peptidase S8 family members. Its N-terminal amino acid residues showed a high degree of sequence similarity with serine proteases from nematophagous and entomopathogenic fungi. Based on the PrC amino acid sequence, the three-dimensional structure has been predicted and compared with that of protease K. Our results provide a basis for further understanding the molecular mechanism of C. rosea infection of nematodes. Such knowledge could be explored for improving by genetic engineering the effectiveness of the use of fungal infections to control parasitic nematodes.