Open AccessInteraction of the small heat shock protein with molecular mass 25 kDa (hsp25) with actin
Author(s) -
Panasenko Olesya O.,
Kim Maria V.,
Marston Steven B.,
Gusev Nikolai B.
Publication year - 2003
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1046/j.1432-1033.2003.03449.x
Subject(s) - heat shock protein , molecular mass , shock (circulatory) , actin , chemistry , microbiology and biotechnology , biophysics , biology , biochemistry , medicine , gene , enzyme
The interaction of heat shock protein with molecular mass 25 kDa (HSP25) and its point mutants S77D + S81D (2D mutant) and S15D + S77D + S81D (3D mutant) with intact and thermally denatured actin was analyzed by means of fluorescence spectroscopy and ultracentrifugation. Wild type HSP25 did not affect the polymerization of intact actin. The HSP25 3D mutant decreased the initial rate without affecting the maximal extent of intact actin polymerization. G‐actin heated at 40–45 °C was partially denatured, but retained its ability to polymerize. The wild type HSP25 did not affect polymerization of this partially denatured actin. The 3D mutant of HSP25 increased the initial rate of polymerization of partially denatured actin. Heating at more than 55 °C induced complete denaturation of G‐actin. Completely denatured G‐actin cannot polymerize, but it aggregates at increased ionic strength. HSP25 and especially its 2D and 3D mutants effectively prevent salt‐induced aggregation of completely denatured actin. It is concluded that the interaction of HSP25 with actin depends on the state of both actin and HSP25. HSP25 predominantly acts as a chaperone and preferentially interacts with thermally unfolded actin, preventing the formation of insoluble aggregates.