Abstract
The native serpin state is kinetically trapped. However, under mildly destabilizing conditions, the conformational landscape changes, and a number of nonnative conformations with increased stability can be readily formed. The ability to undergo structural change is due to intrinsic strain within the serpin's tertiary fold, which is utilized for proteinase inhibition but renders the protein susceptible to aberrant folding and self-association. The relationship between these various conformations is poorly understood. Antichymotrypsin (ACT) is an inhibitory serpin that readily forms a number of inactive conformations, induced via either environmental stress or interaction with proteinases. Here we have used a variety of biophysical and structural techniques to characterize the relationship between some of these conformations. Incubation of ACT at physiological temperature results in the formation of a range of conformations, including both polymer and misfolded monomer. The ability to populate these nonnative states and the native conformation reflects an energy landscape that is very sensitive to the solution conditions. X-ray crystallography reveals that the misfolded monomeric conformation is in the delta conformation. Further polymerization and seeding experiments show that the delta conformation is an end point in the misfolding pathway of ACT and not an on-pathway intermediate formed during polymerization. The observation that ACT readily forms this inactive conformation at physiological temperature and pH suggests that it may have a role in both health and disease.
| Original language | English |
|---|---|
| Journal | Journal of Molecular Biology |
| Volume | 403 |
| Issue number | 3 |
| Pages (from-to) | 459-467 |
| Number of pages | 9 |
| ISSN | 0022-2836 |
| DOIs | |
| Publication status | Published - 29.10.2010 |
Funding
This work was supported by the Australian Synchrotron Research Program , which is funded by the Commonwealth of Australia under the Major National Research Facilities Program. Use of the Advanced Photon Source was supported by the US Department of Energy, Basic Energy Sciences, Office of Energy Research. GM/CA CAT has been funded, in whole or in part, with US Federal funds from the National Cancer Institute ( Y1-CO-1020 ) and the National Institute of General Medical Science ( Y1-GM-1104 ). S.C.F. was supported by a National Health and Medical Research Council of Australia (NHMRC) Industry Fellowship. M.W.P. is an Australian Research Council Federation Fellow and NHMRC Honorary Fellow. S.P.B. is an NHMRC Research Fellow. This work was supported, in part, by a program grant from the NHMRC. We would like to thank Dr. J. Huntington for providing the model structures for the intermediate and polymer structures seen in Fig. 1 . We would also like to thank Dr. S. McGowan for critical appraisal of the manuscript.
Research Areas and Centers
- Academic Focus: Center for Infection and Inflammation Research (ZIEL)
