Kawamukai M, Kishimoto J, Utsumi R, Himeno M, Komano T, Aiba H
J Bacteriol. 1985 Nov;164(2):872-7. doi: 10.1128/jb.164.2.872-877.1985.
We constructed cya-lac protein and operon fusion plasmids in vitro. The effect of cyclic AMP (cAMP) on cya expression was examined by measuring the synthesis of beta-galactosidase in Escherichia coli cells containing fused plasmids. In the cya-lacZ fused protein system, cya expression was strongly repressed by exogenous cAMP. Functional cAMP receptor protein (CRP) was necessary for this effect. On the other hand, in a tet-lacZ fused protein as a control system, tet expression was not affected by cAMP. The inhibition of cya expression by cAMP was also observed in the cya-lac fused operon system, although it was necessary to increase the amount of cAMP or CRP in the cells to detect the effect. The results indicate that cAMP-CRP is a negative regulator of cya expression at the level of transcription.
我们在体外构建了cya-lac蛋白和操纵子融合质粒。通过测量含有融合质粒的大肠杆菌细胞中β-半乳糖苷酶的合成，研究了环磷酸腺苷（cAMP）对cya表达的影响。在cya-lacZ融合蛋白系统中，外源性cAMP强烈抑制cya表达。这种效应需要功能性的cAMP受体蛋白（CRP）。另一方面，在作为对照系统的tet-lacZ融合蛋白中，tet表达不受cAMP影响。在cya-lac融合操纵子系统中也观察到cAMP对cya表达的抑制作用，尽管需要增加细胞中cAMP或CRP的量才能检测到这种效应。结果表明，cAMP-CRP在转录水平上是cya表达的负调节因子。
