Whitlow K J, Polglase W J
J Bacteriol. 1975 Jan;121(1):9-12. doi: 10.1128/jb.121.1.9-12.1975.
Growth of streptomycin-dependent mutants of Escherichia coli K-12 was insensitive to valine when dihydrostreptomycin was present in a nonlimiting concentration in glucose-salts medium. Acetohydroxy acid synthase was derepressed under these conditions, owing to relaxation of catabolite repression. Valine sensitivity and catabolite repression were restored when streptomycin-dependent E. coli K-12 mutants were grown with limiting dihydrostreptomycin. End product repression of acetohydroxy acid synthase under conditions of relaxed catabolite repression was effected by any two (or more) end products except the combination valine plus isoleucine, which caused derepression. Single end products had no detectable effect on acetohydroxy acid synthase formation.
当二氢链霉素在葡萄糖盐培养基中以非限制浓度存在时，大肠杆菌K - 12链霉素依赖型突变体的生长对缬氨酸不敏感。在这些条件下，由于分解代谢物阻遏的松弛，乙酰羟酸合酶被去阻遏。当链霉素依赖型大肠杆菌K - 12突变体在有限的二氢链霉素存在下生长时，缬氨酸敏感性和分解代谢物阻遏得以恢复。在分解代谢物阻遏松弛的条件下，除缬氨酸加异亮氨酸的组合会导致去阻遏外，任何两种（或更多）终产物都会对乙酰羟酸合酶产生终产物阻遏作用。单一终产物对乙酰羟酸合酶的形成没有可检测到的影响。
