Kosturko L D, Daub E, Murialdo H
Department of Molecular Biology and Biochemistry, Hall-Atwater Laboratory, Wesleyan University, Middletown, CT 06457.
Nucleic Acids Res. 1989 Jan 11;17(1):317-34. doi: 10.1093/nar/17.1.317.
The interaction of E. coli's integration Host Factor (IHF) with fragments of lambda DNA containing the cos site has been studied by gel-mobility retardation and electron microscopy. The cos fragment used in the mobility assays is 398 bp and spans a region from 48,298 to 194 on the lambda chromosome. Several different complexes of IHF with this fragment can be distinguished by their differential mobility on polyacrylamide gels. Relative band intensities indicate that the formation of a complex between IHF and this DNA fragment has an equilibrium binding constant of the same magnitude as DNA fragments containing lambda's attP site. Gel-mobility retardation and electron microscopy have been employed to show that IHF sharply bends DNA near cos and to map the bending site. The protein-induced bend is near an intrinsic bend due to DNA sequence. The position of the bend suggests that IHF's role in lambda DNA packaging may be the enhancement of terminase binding/cos cutting by manipulating DNA structure.
通过凝胶迁移率阻滞实验和电子显微镜技术，研究了大肠杆菌整合宿主因子（IHF）与含有粘性末端位点（cos位点）的λ噬菌体DNA片段之间的相互作用。用于迁移率分析的cos片段为398bp，跨越λ染色体上从48,298到194的区域。IHF与该片段形成的几种不同复合物可通过它们在聚丙烯酰胺凝胶上的不同迁移率来区分。相对条带强度表明，IHF与该DNA片段之间形成复合物的平衡结合常数与含有λ噬菌体附着位点（attP位点）的DNA片段的平衡结合常数大小相同。凝胶迁移率阻滞实验和电子显微镜技术已被用于证明IHF使靠近cos位点的DNA急剧弯曲，并确定弯曲位点。蛋白质诱导的弯曲靠近由于DNA序列导致的固有弯曲。弯曲的位置表明，IHF在λ噬菌体DNA包装中的作用可能是通过操纵DNA结构来增强末端酶结合/cos位点切割。
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