L-Canavanine and protein synthesis in the tobacco hornworm Manduca sexta.
L-Canavanine, a nonprotein amino acid of certain leguminous plants, manifests potent insecticidal properties in a canavanine-sensitive insect such as the tobacco hornworm Manduca sexta (L.) (Sphingidae). This arginine analog is activated and aminoacylated by arginyl-tRNA synthetase and incorporated into nascent polypeptide chains to create structurally aberrant, canavanine-containing proteins. Analysis of incorporation of [3H]leucine into protein in M. sexta larvae that had been injected with canavanine revealed that this arginine analog stimulates protein synthesis. During the first 3 hr after injection of canavanine, canavanine-mediated net stimulation of protein formation was readily discerned. Thereafter, the stimulation of protein synthesis appeared to be offset by the preferential degradation of anomalous proteins. Double-label protein-turnover experiments with larvae injected with [14C]canavanine- and [3H]arginine-containing hemolymph proteins showed that canavanine-containing proteins were degraded preferentially.
Rosenthal
G A
GA
Dahlman
D L
DL
D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D001120:Arginine / Q000378:metabolism; D002172:Canavanine / Q000378:metabolism / Q000494:pharmacology*; D005216:Fat Body / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000096:biosynthesis; D006458:Hemolymph / Q000378:metabolism; D007700:Kinetics; D007814:Larva / Q000378:metabolism; D007915:Lepidoptera / Q000378:metabolism*; D007930:Leucine / Q000378:metabolism; D009036:Moths / Q000187:drug effects / Q000378:metabolism*; D009132:Muscles / Q000378:metabolism; D014176:Protein Biosynthesis
D000596:Amino Acids; D006360:Heat-Shock Proteins; D002172:Canavanine; D001120:Arginine; D007930:Leucine