Submitted to: American Society of Cell Biology Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: December 5, 2000
Publication Date: N/A
Technical Abstract: Aminopeptidase activity is described for the plant parasitic nematode, Heterodera glycines. H. glycines spends a portion of its life cycle in a free-living stage similar to Caenorhabditis elegans, but undergoes dramatic changes in behavior and development upon parasitizing the host plant. Results obtained from colorimetric enzyme assays, chromatographic and electrophoretic fractionations, and differential centrifugation show that H. glycines aminopeptidase differs from that of C. elegans in subcellular distribution and number of active components. Activity detected with the substrate alanine p-nitroanilide (Ala pNA) is associated primarily with membranes in H. glycines. Depending upon developmental stage, this accounts for 53 to 75 percent of total aminopeptidase activity. C. elegans preparations have over 95 percent of activity present in the cytosolic fraction. The apparent molecular weight of soluble C. elegans enzyme is 70-80 kDa, and there is also activity at 70-80 kDa in H. glycines. However, most (>80 percent) of the soluble activity in this parasite is present as a high molecular weight component (>240 kDa). Affinity of the enzyme for Ala pNA is similar in the two species, but differences appear with other AApNA substrates. Preliminary experiments with two additional nematodes, the free-living Panagrellus redivivus and the plant parasite Meloidogyne incognita suggest that subcellular distribution and substrate preferences are consistent with C. elegans and H. glycines, respectively. Discovery of basic biochemical differences between parasitic and non-parasitic species provides opportunities for the design of novel controls such as narrowly targeted enzyme inhibitors.