相互分離且距離較遠(yuǎn)的DNA區(qū)域能夠相互作用是通過一種特異蛋白誘導(dǎo)的突觸蛋白-DNA復(fù)合體作為媒介的,。這種現(xiàn)象普遍存在,，在基因工程中的地位也至關(guān)重要。雖然這種相互作用通常發(fā)生在兩點(diǎn)之間,，而現(xiàn)在已經(jīng)發(fā)現(xiàn)三個(gè)特定DNA 區(qū)域也能夠相互作用,，并且已經(jīng)有相應(yīng)的模式。
用原子力顯微鏡觀測這種模式為EcoRII的限制性內(nèi)切酶,，可以顯示和表征涉及到三個(gè)DNA結(jié)合點(diǎn)的突觸蛋白-DNA復(fù)合體,。該復(fù)合體用圖像顯示出來是雙環(huán)結(jié)構(gòu)，通過環(huán)上的長度測量可以證明特異性蛋白在復(fù)合體中所處的位置,。蛋白質(zhì)的體積測量顯示,，EcoRII二聚體是三點(diǎn)突觸體的核心。蛋白質(zhì)的體積數(shù)據(jù)顯示,，該二聚體形式的蛋白質(zhì)也是形成其它類型突觸復(fù)合體的原因,。
目前，研究人員正在探討應(yīng)用上述結(jié)果去認(rèn)識(shí)蛋白質(zhì)-DNA反應(yīng)的機(jī)制,。
英文原文鏈接：http://pubs.acs.org/cgi-bin/abstract.cgi/bichaw/2007/46/i39/abs/bi701123u.html
Biochemistry, 46 (39), 11128 -11136, 2007. 10.1021/bi701123u S0006-2960(70)01123-6
Web Release Date: September 11, 2007 Copyright © 2007 American Chemical Society
Direct Visualization of the EcoRII-DNA Triple Synaptic Complex by Atomic Force Microscopy
Luda S. Shlyakhtenko, Jamie Gilmore, Alex Portillo, Gintautas Tamulaitis, Virginijus Siksnys, and Yuri L. Lyubchenko*
Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, 986025 Nebraska Medical Center, Omaha, Nebraska 68198-6025, and Institute of Biotechnology, Graiciuno 8, LT-02241 Vilnius, Lithuania
Received June 6, 2007
Revised Manuscript Received August 20, 2007
Abstract
Interactions between distantly separated DNA regions mediated by specialized proteins lead to the formation of synaptic protein-DNA complexes. This is a ubiquitous phenomenon which is critical in various genetic processes. Although such interactions typically occur between two sites, interactions among three specific DNA regions have been identified, and a corresponding model has been proposed. Atomic force microscopy was used to test this model for the EcoRII restriction enzyme and provide direct visualization and characterization of synaptic protein-DNA complexes involving three DNA binding sites. The complex appeared in the images as a two-loop structure, and the length measurements proved the site specificity of the protein in the complex. The protein volume measurements showed that an EcoRII dimer is the core of the three-site synaptosome. Other complexes were identified and analyzed. The protein volume data showed that the dimeric form of the protein is responsible for the formation of other types of synaptic complexes as well. The applications of these results to the mechanisms of the protein-DNA interactions are discussed
