The critical role of hinge-region expulsion in the induced-fit heparin binding mechanism of antithrombin.
The critical role of hinge-region expulsion in the induced-fit heparin binding mechanism of antithrombin.
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DOI：
10.1016/j.jmb.2009.01.028
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发表时间：
2009-03-13
影响因子：
5.6
通讯作者：
Huntington, James A.
中科院分区：
文献类型：
--
作者：
Langdown, Jonathan;Belzar, Klara J.;Savory, Wendy J.;Baglin, Trevor P.;Huntington, James A.
Antithrombin (AT) is the most important inhibitor of the coagulation proteases. Its activity is stimulated by glycosaminoglycans such as heparin, through allosteric and template mechanisms. AT utilises an induced-fit mechanism to bind with high affinity to a pentasaccharide sequence found in about one-third of heparin chains. The conformational changes behind this mechanism have been characterised by several crystal structures of AT in the absence and presence of the pentasaccharide. Pentasaccharide binding ultimately results in a conformational change that improves affinity by about 1000-fold. Crystal structures show several differences, including the expulsion of the hinge region of the reactive centre loop from β-sheet A, known to be critical for the allosteric activation of AT. Here we present data that reveals an energetically distinct intermediate on the path to full activation, where the majority of conformational changes have already occurred. A crystal structure of this intermediate shows that the hinge region is in a native like state, in spite of having the pentasaccharide bound in the normal fashion. We engineered a disulphide bond to lock the hinge in its native position to determine the energetic contributions of the initial and final conformational events. Approximately 60% of the free energy contribution of conformational change is provided by the final step of hinge region expulsion and subsequent closure of the main β-sheet A. A new analysis of the individual structural changes provides a plausible mechanism for propagation of conformational change from the heparin binding site to the remote hinge region in β-sheet A.
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影响因子：
15.9
作者：
Ishiguro, K;Kojima, T;Saito, H
通讯作者：
Saito, H
影响因子：
10.4
作者：
Rau, J. C.;Beaulieu, L. M.;Church, F. C.
通讯作者：
Church, F. C.
影响因子：
4.8
作者：
Johnson, DJD;Huntington, JA
通讯作者：
Huntington, JA
影响因子：
2.9
作者：
Huntington, JA;Olson, ST;Gettins, PGW
通讯作者：
Gettins, PGW
DOI：
10.1107/s0907444995016477
发表时间：
1996-07-01
期刊：
ACTA CRYSTALLOGRAPHICA SECTION D-BIOLOGICAL CRYSTALLOGRAPHY
影响因子：
--
作者：
Kleywegt, GJ
通讯作者：
Kleywegt, GJ