CONSENSUS DNA SITE FOR THE ESCHERICHIA-COLI CATABOLITE GENE ACTIVATOR PROTEIN (CAP) - CAP EXHIBITS A 450-FOLD HIGHER AFFINITY FOR THE CONSENSUS DNA SITE THAN FOR THE ESCHERICHIA-COLI LAC DNA SITE
CONSENSUS DNA SITE FOR THE ESCHERICHIA-COLI CATABOLITE GENE ACTIVATOR PROTEIN (CAP) - CAP EXHIBITS A 450-FOLD HIGHER AFFINITY FOR THE CONSENSUS DNA SITE THAN FOR THE ESCHERICHIA-COLI LAC DNA SITE
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DOI：
10.1093/nar/17.24.10295
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发表时间：
1989-12-25
影响因子：
14.9
通讯作者：
GUNASEKERA, A
中科院分区：
文献类型：
--
作者：
EBRIGHT, RH;EBRIGHT, YW;GUNASEKERA, A
我们合成了两个40碱基对的DNA片段，一个片段含有CAP的共有DNA位点（片段“ICP”），另一个片段含有E. CAP的大肠杆菌lac启动子DNA位点（片段“LCAP”）。我们已经研究了CAP的两个DNA片段的结合使用硝酸纤维素过滤结合试验。在标准条件下（[NaCl] = 200 mM，pH = 7.3），CAP对ICAP的亲和力比对LCAP的亲和力高450倍。结合平衡的盐依赖性表明CAP与ICAP形成8个离子对，而与LCAP形成6个离子对。CAP与ICAP相对于LCAP的相互作用的结合自由能的差异的大约一半可归因于离子对形成的这种差异。结合平衡的pH依赖性表明，8个CAP-ICAP离子对和6个CAP-LCAP离子对不涉及CAP的His残基。
We have synthesized two 40 base pair DNA fragments; one fragments contains the consensus DNA site for CAP (fragment ''ICP''); the other fragment contains the E. coli lac promoter DNA site for CAP (fragment ''LCAP''). We have investigated the binding of CAP to the two DNA fragments using the nitrocellulose filter binding assay. Under standard conditions ([NaCl] = 200 mM, pH = 7.3), CAP exhibits a 450-fold higher affinity for ICAP than for LCAP. The salt dependence of the binding equilibrium indicates that CAP makes eight ion pairs with ICAP, but only six ion pairs with LCAP. Approximately half of the difference in binding free energy for interaction of CAP with ICAP vs. LCAP is attributable to this difference in ion-pair formation. The pH dependence of the binding equilibrium indicates that the eight CAP-ICAP ion pairs and the six CAP-LCAP ion pairs do not involve His residues of CAP.