| Regional Biophysics Meeting 2005, March 16-20, Zreče, Slovenia | [ProtBiophys] |
Small heat-shock proteins are low molecular mass proteins, abundant in all kingdoms of life. Their role is to maintain substrate proteins in folding-competent state [1, 2]. These small heat-shock proteins generally form large multimeric complexes; the oligomers usually have a dynamic quaternary structure [3]. The oligomerization is a prerequisite for the chaperone function [4], but the relationship between the oligomer size and the chaperone activity is not well understood. In this work, we examined two members of this family: bovine alpha-crystallin, and a prokaryotic protein, HSP 16.5 from Methanococcus jannaschii (MjHSP 16.5). Pressure is an adequate tool for studying this question, because moderate pressure generate elastic changes in the protein, and affects mostly the quaternary structure. Both cases we observed, that the chaperone activity of these proteins can be enhanced by short pressure treatment at 100-400 MPa. We studied by various spectroscopic methods the underlying structural changes. The results showed, that mostly the quaternary structure altered during this treatment, and it should be the key factor in the chaperone activity. Our results showed that the enhancement of the chaperone activity does not require the increase of the oligomer size [5] as was assumed earlier [6], and that the pressure is a very powerful tool studying the function of oligomeric proteins. [1] Lee, G.J. et al., EMBO J. 1997, 16, 659-671. [2] Ehrnsperger M. et. al., EMBO J. 1997, 16, 221-229. [3] Bova, M. P. et. al. J. Biol. Chem. 1997, 272, 29511-29517. [4] Sonja Studer et al., Eur. J. Biochem. 2002, 269, 3578-3586. [5] Böde, Cs. et. al. Biochem. J. 2003, 370, 859-866 [6] Burgio, M.R. et al. Biochem. Biophys. Res. Comm. 2000, 268, 426-432
Email: csabi@puskin.sote.hu
Address: Csaba Bode, Semmelweis University Department for Biophysics and Radiation Biology, H-1444 Budapest P.O.B 263.