Chattopadhyay Rima, Parrack Pradeep
Department of Biochemistry, Bose Institute, P-1/12 CIT Scheme VII M, Kolkata 700054, India.
Arch Biochem Biophys. 2006 Mar 1;447(1):80-6. doi: 10.1016/j.abb.2006.01.001. Epub 2006 Jan 23.
The cyclic AMP receptor protein (CRP) from Escherichia coli, involved in the transcriptional regulation of a number of genes and operons, works by binding to specific sites upstream of promoters. CRP also binds cyclic AMP (cAMP), and this binding, which causes conformational changes in CRP, is mandatory for its activity. A cAMP-dependent variation in the conformation as well as biological activity of E. coli CRP has been reported, with the cAMP-CRP complex formed at high cAMP concentrations resembling the uncomplexed apoprotein CRP. CRP from Vibrio cholerae, which plays an important role in the regulation of virulence gene expression, has a 95% sequence identity with the E. coli protein. We have purified and characterized V. cholerae CRP and studied its transcription activation properties as a function of increasing cAMP concentrations. A biphasic dependence on cAMP levels was observed, similar to that found for E. coli CRP. The implications of these results on regulation of cAMP-CRP dependent promoters in V. cholerae has been discussed.
来自大肠杆菌的环磷酸腺苷受体蛋白（CRP）参与许多基因和操纵子的转录调控，其作用方式是与启动子上游的特定位点结合。CRP还结合环磷酸腺苷（cAMP），这种结合会导致CRP构象发生变化，是其发挥活性所必需的。据报道，大肠杆菌CRP的构象和生物活性存在cAMP依赖性变化，在高cAMP浓度下形成的cAMP-CRP复合物类似于未复合的载脂蛋白CRP。霍乱弧菌的CRP在毒力基因表达调控中起重要作用，与大肠杆菌蛋白的序列同一性为95%。我们已纯化并鉴定了霍乱弧菌CRP，并研究了其作为cAMP浓度增加函数的转录激活特性。观察到对cAMP水平呈双相依赖性，类似于在大肠杆菌CRP中发现的情况。已讨论了这些结果对霍乱弧菌中cAMP-CRP依赖性启动子调控的影响。
