Rosenthal G A, Dahlman D L
Proc Natl Acad Sci U S A. 1986 Jan;83(1):14-8. doi: 10.1073/pnas.83.1.14.
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.
L-刀豆氨酸是某些豆科植物中的一种非蛋白质氨基酸,在对刀豆氨酸敏感的昆虫(如烟草天蛾烟草天蛾(L.)(天蛾科))中表现出强大的杀虫特性。这种精氨酸类似物被精氨酰-tRNA合成酶激活并氨酰化,并入新生的多肽链中,形成结构异常的含刀豆氨酸的蛋白质。对注射了刀豆氨酸的烟草天蛾幼虫中[3H]亮氨酸掺入蛋白质的分析表明,这种精氨酸类似物刺激蛋白质合成。在注射刀豆氨酸后的最初3小时内,可以很容易地看出刀豆氨酸介导的蛋白质形成的净刺激作用。此后,蛋白质合成的刺激作用似乎被异常蛋白质的优先降解所抵消。对注射了含[14C]刀豆氨酸和[3H]精氨酸的血淋巴蛋白的幼虫进行的双标记蛋白质周转实验表明,含刀豆氨酸的蛋白质被优先降解。