Single base-pair precision and structural rigidity in a small IHF-induced DNA loop.
Single base-pair precision and structural rigidity in a small IHF-induced DNA loop.
复制标题
IHF 诱导的小 DNA 环中的单碱基对精度和结构刚性。
DOI：
10.1006/jmbi.1995.0548
复制
发表时间：
1995
期刊：
影响因子：
--
通讯作者：
Landy,A
中科院分区：
文献类型：
--
作者：
Nunes-Duby,SE;Smith-Mungo,LI;Landy,A
The prokaryotic integration host factor (IHF) is a DNA-binding protein that binds to specific DNA sites as a heterodimer. Genetic and mutational analyses have previously identified asymmetric protein-DNA contacts by the individual subunits. By exploiting the unique sequence and positional context of one IHF binding site, H′ in Lambda attachment sites (attsites), we have identified a symmetry element of binding and have localized the functional bend center to the center of this symmetry. A shift of the H′ bend center by a single base-pair to the right or to the left within the very tight loop formed with Lambda integrase (int) and IHF inatt-site “intrasomes” severely reduces recombination. This suggests that a precise, but wrongly positioned, DNA bend within a loop constant length negatively influences the juxtaposition or “phasing” of the core-type and arm-type Int binding sites by differentially affecting the length of each leg of the loop. Furthermore, ten base-pair insertions within this loop that should not interfere with correct helical phasing are sensed in a position-dependent manner. Distal insertions abolish recombination, whereas proximal or double insertions (in both legs of the loop) are well tolerated.
