Submitted to: Journal of Federation of American Societies for Experimental Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 21, 2002
Publication Date: N/A
Interpretive Summary: Plant-parasitic nematodes attack all crops of agricultural importance, causing over $10 billion in losses annually to U.S. farmers. One problem facing growers is that environmental concerns will result in the elimination of the most extensively used chemical nematicide from the United States within the next few years. This makes the discovery of environmentally and economically sound replacement control agents critical. One approach is to identify natural targets in nematodes that can provide the basis for development of novel control approaches. In this paper we report the discovery of an important gene called the proconvertase gene in the soybean cyst nematode, a serious pest in the United States. The proconvertase enzyme is essential for nematode development and survival, and may be associated with egg-laying, growth and molting in this pest. This discovery is significant because it is the first report of this gene and enzyme in any plant-parasitic nematode, and the importance of the gene makes it a prime natural target at which to focus development of a variety of natural control startegies. This information will be used by researchers in the agrochemical and agricultural biotechnology industries who are developing safe, selective and cutting-edge methods for nematode control.
Technical Abstract: Proprotein convertases (PCs) are evolutionarily conserved enzymes responsible for processing the precursors of many bioactive peptides in mammals. The invertebrate homologues of PC2 play important roles during development that makes the enzyme a good target for practical applications in pest management. Screening of a plant nematode Heterodera glycines cDNA library resulted in isolation of a full-length clone encoding a PC2-like precursor. The deduced protein (MW = 74.2 kD) exhibits strong amino acid homology to all known PC2s, including human, and shares the main structural characteristics: signal peptide; prosegment; catalytic domain, with D/H/S catalytic triad, PC2-specific residues and 7B2 binding sites; P domain (with RRGDT pentapeptide); and carboxyl terminus. Comparative analysis of PC2s from15 species discloses the presence of an insert in the catalytic domain unique to nematodes. Expression of PC2-like mRNA found in eggs and juveniles was undetectable in adult stages of H. glycines. Nucleotide analysis reveals distinctive differences in base composition and codon usage between H. glycines and other invertebrate PC2s. The H. glycines cDNA clone encoding PC2 is the first one isolated from plant- parasitic nematodes.