Stenzel T T, Patel P, Bastia D
Cell. 1987 Jun 5;49(5):709-17. doi: 10.1016/0092-8674(87)90547-2.
The integration host factor (IHF) of Escherichia coli is necessary for maintenance of pSC101. The protein binds specifically to the replication origin of the plasmid, in the AT-rich region located immediately adjacent to the left, weak binding site for the plasmid-encoded initiator protein. DNAase I and OH- radical footprinting experiments showed that IHF protects 49 bp of the DNA at the origin region. Methylation protection analyses revealed that IHF contacts purine residues in both the major and minor grooves of the DNA. Electrophoretic analyses showed that IHF binds to bent DNA, and the protein binding further enhances the degree of DNA bending. Site-directed mutagenesis of three of the contact points not only abolished binding of the protein to the DNA but also inactivated the replication origin. Therefore, binding of IHF to the ori sequence most probably is necessary for initiation of plasmid replication.
大肠杆菌的整合宿主因子（IHF）是维持pSC101所必需的。该蛋白特异性结合质粒的复制起点，位于富含AT的区域，紧邻质粒编码的起始蛋白的左侧弱结合位点。DNA酶I和羟基自由基足迹实验表明，IHF保护起点区域49bp的DNA。甲基化保护分析显示，IHF与DNA大沟和小沟中的嘌呤残基接触。电泳分析表明，IHF与弯曲的DNA结合，并且该蛋白的结合进一步增强了DNA的弯曲程度。三个接触点的定点诱变不仅消除了该蛋白与DNA的结合，还使复制起点失活。因此，IHF与ori序列的结合很可能是质粒复制起始所必需的。
