Studying the interaction between gyrase and DNA using magnetic tweezers  

作　　者：ZHANG ZhiQiang LIU YuRu XIE Ping LI Wei DOU ShuoXing WANG PengYe 

机构地区：[1]Key Laboratory of Soft Matter Physics,Beijing National Laborartory for Condensed Matter Physics,Institute of Physics,Chinese Academy of Sciences,Beijing 100190,China

出　　处：《Chinese Science Bulletin》2012年第27期3560-3566,共7页

基　　金：supported by the National Natural Science Foundation of China (10834014,10974248);the National Basic Research Program of China (2009CB930704)

摘　　要：The DNA gyrase of Escherichia coli plays an essential role in the life of this microorganism.It is unique among all topoisomerases because of its ability to introduce negative supercoils into DNA.This study investigated the single molecular interaction of E.coli gyrase with DNA using magnetic tweezers.The results showed that,in the absence of ATP,gyrase weakly binds the G and T segments.The stretched force of 0.7 pN can gradually destroy the binding,whereas that of 5.9 pN directly destroys it.Addition of high concentrations of norfloxacin enhances gyrase binding to both segments,making them adapt to 5.9 pN.DNA gyrase reduces the plectonemic dimension,which was determined by the bacterial enzyme and not by the pull force.Moreover,it has different affinities for positive supercoils,which it prefers,and negative supercoils.The time distribution of the dissociation of gyrase from DNA has a double-exponential form.We herein propose a model to explain this distribution and compare the results with those of other models.The DNA gyrase of Escherichia coli plays an essential role in the life of this microorganism. It is unique among all topoisomer- ases because of its ability to introduce negative supercoils into DNA. This study investigated the single molecular interaction of E. coli gyrase with DNA using magnetic tweezers. The results showed that, in the absence of ATP, gyrase weakly binds the G and T segments. The stretched force of 0.7 pN can gradually destroy the binding, whereas that of 5.9 pN directly destroys it. Addition of high concentrations of norfloxacin enhances gyrase binding to both segments, making them adapt to 5.9 pN. DNA gyrase reduces the plectonemic dimension, which was determined by the bacterial enzyme and not by the pull force. Moreover, it has different affinities for positive supercoils, which it prefers, and negative supercoils. The time distribution of the dissociation of gyrase from DNA has a double-exponential form. We herein propose a model to explain this distribution and compare the results with those of other models.

关 键 词：DNA解旋酶 分子间相互作用 旋转酶 磁性 超螺旋DNA 大肠埃希氏菌 大肠杆菌 诺氟沙星 

分 类 号：Q504[生物学—生物化学]