Saikrishnan K, Bidya Sagar M, Ravishankar R, Roy S, Purnapatre K, Handa P, Varshney U, Vijayan M
Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, India.
Acta Crystallogr D Biol Crystallogr. 2002 Aug;58(Pt 8):1269-76. doi: 10.1107/s0907444902009599. Epub 2002 Jul 20.
The structures of a new crystal form of free Escherichia coli uracil DNA glycosylase (UDG), containing four molecules in the asymmetric unit, and two forms of its complex with the proteinaceous inhibitor Ugi, containing two and four crystallographically independent complexes, have been determined. A comparison of these structures and the already known crystal structures containing UDG shows that the enzyme can be considered to be made up of two independently moving structural entities or domains. A detailed study of free and DNA-bound human enzyme strengthens this conclusion. The domains close upon binding to uracil-containing DNA, whereas they do not appear to do so upon binding to Ugi. The comparative study also shows that the mobility of the molecule involves the rigid-body movement of the domains superposed on flexibility within domains.
已确定游离的大肠杆菌尿嘧啶DNA糖基化酶（UDG）的一种新晶体形式的结构，其不对称单元中包含四个分子，以及它与蛋白质抑制剂Ugi形成的两种复合物形式的结构，其中包含两个和四个晶体学独立的复合物。对这些结构与已有的含UDG晶体结构进行比较表明，该酶可被视为由两个独立移动的结构实体或结构域组成。对游离的和与DNA结合的人源酶的详细研究强化了这一结论。这些结构域在与含尿嘧啶的DNA结合时会靠近，而在与Ugi结合时似乎不会。比较研究还表明，分子的移动性涉及结构域的刚体运动叠加在结构域内的灵活性之上。
