The Mechanism of CAP-lacRepressor Binding Cooperativity at theE. coliLactose Promoter

摘要: The cyclic AMP receptor protein (CAP) and lactose repressor bind their regulatory sites in the promoter with moderate cooperativity (omega C101 = 11.8(+/- 3.7)). This is significantly reduced by removal of DNA located upstream CAP binding site or substitution dimeric lacI-18 mutant for wild-type tetrameric protein. These results are consistent a mechanism interaction which bends lac binds simultaneously to its operator promoter-distal sequences. Similar values omega were obtained truncation containing O3 pseudooperator one destroyed, suggesting that contacts distal necessary cooperative binding.