Backbone Dynamics of the C-Terminal Domain of Escherichia coli Topoisomerase I in the Absence and Presence of Single-Stranded DNA
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- 作者：Liping Yu ; Chang-Xi Zhu ; Yuk-Ching Tse-Dinh ; and Stephen W. Fesik
- 刊名：Biochemistry
- 出版年：1996
- 出版时间：July 30, 1996
- 年：1996
- 卷：35
- 期：30
- 页码：9661 - 9666
- 全文大小：356K
- 年卷期：v.35,no.30(July 30, 1996)
- ISSN：1520-4995
文摘
The backbone dynamics of the C-terminal DNA-binding domain ofEscherichia colitopoisomerase I has been characterized in the absence and presence ofsingle-stranded DNA by NMRspectroscopy. 15N spin-lattice relaxation times(T1), spin-spin relaxation times(T2), and heteronuclearNOEs were determined for the uniformly 15N-labeled protein.These data were analyzed by using themodel-free formalism to derive the model-free parameters(S2, 
e, andRex) for each backbone N-H bondvector and the overall molecular rotational correlation time(m). The molecular rotationalcorrelationtime m was determined to be 7.49 ± 0.36 ns for thefree and 12.7 ± 1.07 ns for the complexed protein.Several residues were found to be much more mobile than theaverage, including 11 residues at theN-terminus, 2 residues at the C-terminus, and residues 25 and 31-35which are located in a region of theprotein that binds to DNA. The binding of ssDNA to the freeprotein causes a slight increase in the orderparameters (S2) for a small number of residuesand a slight decrease in the order parameters(S2) for themajority of the residues. In particular, upon binding to ssDNA,the mobility of the first 
-helix and thetwo 
-sheets was slightly increased, and the mobility of a fewspecific residues in the loops/turns wasrestricted. These results differ from the previous studies on thebackbone dynamics of molecular complexesin which reduced mobilities were typically observed upon ligandbinding.
e, andRex) for each backbone N-H bondvector and the overall molecular rotational correlation time(m). The molecular rotationalcorrelationtime m was determined to be 7.49 ± 0.36 ns for thefree and 12.7 ± 1.07 ns for the complexed protein.Several residues were found to be much more mobile than theaverage, including 11 residues at theN-terminus, 2 residues at the C-terminus, and residues 25 and 31-35which are located in a region of theprotein that binds to DNA. The binding of ssDNA to the freeprotein causes a slight increase in the orderparameters (S2) for a small number of residuesand a slight decrease in the order parameters(S2) for themajority of the residues. In particular, upon binding to ssDNA,the mobility of the first -helix and thetwo -sheets was slightly increased, and the mobility of a fewspecific residues in the loops/turns wasrestricted. These results differ from the previous studies on thebackbone dynamics of molecular complexesin which reduced mobilities were typically observed upon ligandbinding.© 2004-2018 中国地质图书馆版权所有 京ICP备05064691号 京公网安备11010802017129号 地址：北京市海淀区学院路29号 邮编：100083 电话：办公室：(+86 10)66554848；文献借阅、咨询服务、科技查新：66554700 |