Characterization of intestinally active proteinases of cystnematodes

Abstract

SUMMARY: Cryostat sections of juvenile and adult female stages of the soybean cyst-nematode,Heterodera glycines, were incubated with 4 different naphthylamide-linked peptide substrates to localize and characterize proteinase activity within the animal. Detected activity was restricted to the intestine and 2 distinct classes of proteinase were identified on the basis of substrate specificity and sensitivity to plant proteinase inhibitors. A cathepsin L-like cysteine proteinase activity capable of hydrolysing the synthetic substrates Z-Ala-Arg-Arg-MNA and Z-Phe-Arg-MNA but not Z-Arg-Arg-MNA or L-Arg-NA was inhibited by an engineered variant of a cysteine proteinase inhibitor from rice (Oc-IδD86). The cleavage of Z-Phe-Arg-MNA was sensitive to inhibition by a combination of Oc-IδD86 and cowpea trypsin inhibitor (CpTI). Degenerate oligonucleotide primers were used to amplify fragments of cysteine proteinase genes from 2 cyst-nematodes,H. glycinesandGlobodera pallida. Comparison of theH. glycinesfragment with known genes established highest homology to cathepsin L-like genes. In contrast, the amplifiedG. pallidafragment displayed greatest homology to cathepsin B-like genes fromCaenorhabditis elegans.