Amy N K, Garrett R H
J Bacteriol. 1980 Oct;144(1):232-7. doi: 10.1128/jb.144.1.232-237.1980.
Experiments were performed to determine whether conditions which cause the rapid loss of nitrate reductase activity in Neurospora crassa mycelia were accompanied by the loss of antigenically detectable nitrate reductase protein. When mycelia with nitrate reductase activity were transferred to ammonia media, there was a rapid loss in the reduced nicotinamide adenine dinucleotide-nitrate reductase activity plus the parallel loss of the reduced nicotinamide adenine dinucleotide-diaphorase and the reduced methyl viologen-nitrate reductase activities associated with the nitrate reductase. In addition, there was the loss of cross-reacting material to anti-nitrate reductase antisera that was concomitant with the loss of nitrate reductase activity. When mycelia were exposed to either ammonia plus cycloheximide, nitrate plus cycloheximide, or nitrogen-free media, or to media which lacked an assimilable carbon source, the amount of cross-reacting material declined in concert with the nitrate reductase activity. The mutant nit-6, which lacks nitrite reductase activity, was exposed to ammonia or nitrate plus cycloheximide media. The nitrate reductase and the amount of cross-reacting material declined together as in the wild-type mycelia. We conclude that the loss of nitrate reductase activity was accompanied by the specific loss of this protein and that no pool of inactivated nitrate reductase molecules existed.
开展实验以确定在粗糙脉孢菌菌丝体中导致硝酸还原酶活性快速丧失的条件是否伴随着抗原可检测的硝酸还原酶蛋白的丧失。当具有硝酸还原酶活性的菌丝体转移至氨培养基时，还原型烟酰胺腺嘌呤二核苷酸 - 硝酸还原酶活性迅速丧失，同时与硝酸还原酶相关的还原型烟酰胺腺嘌呤二核苷酸 - 黄递酶和还原型甲基紫精 - 硝酸还原酶活性也平行丧失。此外，与抗硝酸还原酶抗血清发生交叉反应的物质也丧失，且与硝酸还原酶活性的丧失同步。当菌丝体暴露于氨加放线菌酮、硝酸盐加放线菌酮、无氮培养基或缺乏可同化碳源的培养基时，交叉反应物质的量与硝酸还原酶活性同步下降。缺乏亚硝酸还原酶活性的突变体nit - 6暴露于氨或硝酸盐加放线菌酮培养基中。与野生型菌丝体一样，硝酸还原酶和交叉反应物质的量一起下降。我们得出结论，硝酸还原酶活性的丧失伴随着该蛋白的特异性丧失，并且不存在失活的硝酸还原酶分子池。
