Multivalent DNA-binding properties of the HMG-1 proteins.

HMG-I proteins are DNA-binding proteins thought to affect the formation and function of transcription complexes. Each protein contains three DNA-binding motifs, known as AT-hooks, that bind in the minor groove of AT tracts in DNA. Multiple AT-hooks within a polypeptide chain should contact multiple AT tracts, but the rules governing these interactions have not been defined. In this study, we demonstrate that high-affinity binding uses two or three appropriately spaced AT tracts as a single multivalent binding site. These principles have implications for binding to regulatory elements such as the interferon beta enhancer, TATA boxes, and serum response elements. IMAGES:

高迁移率族蛋白I（HMG-I proteins）是一类DNA结合蛋白，被认为可影响转录复合物的形成与功能。每一种该类蛋白均包含三种被称为AT钩子（AT-hooks）的DNA结合基序，这些基序能够结合于DNA中AT序列区段的小沟内。一条多肽链上的多个AT钩子理应能够与多个AT序列区段产生接触，但调控此类相互作用的具体规则尚未明确。本研究证实，高亲和力结合会将两个或三个间距适宜的AT序列区段作为单个多价结合位点。这些结合原则对于干扰素β增强子、TATA盒以及血清反应元件等调控元件的结合具有参考意义。图像：