Saito K, Kikuchi T, Shirakawa H, Yoshida M
Department of Biological Science and Technology Science University of Tokyo, Noda, Chiba, 278-8510, Japan.
J Biochem. 1999 Feb;125(2):399-405. doi: 10.1093/oxfordjournals.jbchem.a022300.
High mobility group (HMG) protein 1 contains two DNA binding motifs, called HMG1/2-boxes, linked with a linker region. The functional relationships between the two boxes and the mechanism of involvement of the linker region for effective binding of HMG1 were examined. The binding analyses of truncated HMG1 peptides with DNA indicated that the structural array of two boxes stabilizes the interaction of HMG1 with DNA. The mutation analyses of the linker region suggested that the region is equipped with tolerance for the deletion of a few amino acid residues to allow appropriate binding of the two boxes with DNA, and that the basic cluster in the linker sequence is in a position to interact with DNA. The existence of tolerance for the linker sequence was found to be conserved during the evolution of HMG1 protein homologues. A structural model for array of two boxes associating with DNA minor groove was constructed on the basis of the experimental results and energy minimization. The model proposes that the DNA binding region in HMG1 covers an 18 bp DNA region and induces its bending by about 140 degrees. The linker region may function to maintain the structural array of two HMG1/2-boxes by direct interaction with DNA.
高迁移率族（HMG）蛋白1包含两个与连接区相连的DNA结合基序，称为HMG1/2框。研究了两个框之间的功能关系以及连接区参与HMG1有效结合的机制。截短的HMG1肽与DNA的结合分析表明，两个框的结构排列稳定了HMG1与DNA的相互作用。连接区的突变分析表明，该区域对少数氨基酸残基的缺失具有耐受性，以允许两个框与DNA进行适当结合，并且连接序列中的碱性簇能够与DNA相互作用。发现连接序列的耐受性在HMG1蛋白同源物的进化过程中是保守的。基于实验结果和能量最小化构建了与DNA小沟结合的两个框排列的结构模型。该模型提出，HMG1中的DNA结合区域覆盖18bp的DNA区域，并使其弯曲约140度。连接区可能通过与DNA直接相互作用来维持两个HMG1/2框的结构排列。
