Archives of Biochemistry and Biophysics 454 (2006) 32–41 www.elsevier.com/locate/yabbi 0003-9861/$ - see front matter © 2006 Elsevier Inc. All rights reserved. doi:10.1016/j.abb.2006.07.014 Structure and properties of K141E mutant of small heat shock protein HSP22 (HspB8, H11) that is expressed in human neuromuscular disorders Maria V. Kim a,1 , Alexei S. Kasakov a,1 , Alim S. Seit-Nebi a , Steven B. Marston b , Nikolai B. Gusev a,¤ a Department of Biochemistry, School of Biology, Moscow State University, Moscow 119992, Russia b Imperial College, School of Medicine at National Heart and Lung Institute, Dovehouse Street, London SW3 6LY, UK Received 22 June 2006, and in revised form 24 July 2006 Available online 11 August 2006 Abstract Some properties of the K141E mutant of human HSP22 that is expressed in distal hereditary motor neuropathy were investigated. This mutation slightly decreased intrinsic Xuorescence of HSP22 and induced changes in the far UV CD spectra that correlate with increase of disordered structure. Destabilized K141E mutant was more susceptible to trypsinolysis than the wild type protein. Mutation K141E did not signiWcantly aVect the hydrophobic properties measured by bis-ANS binding and did not aVect the quaternary structure of HSP22. With insulin as a substrate the chaperone-like activity of K141E mutant and the wild type protein were similar. However with alcohol dehydrogenase and rhodanese the chaperone-like activity of K141E mutant was remarkably lower than the corresponding activ- ity of the wild type protein. It is concluded that K141E mutation induces destabilization of HSP22 structure and probably by this means diminish the chaperone-like activity of HSP22 with certain protein substrates. © 2006 Elsevier Inc. All rights reserved. Keywords: Small heat shock proteins; Oligomeric structure; Chaperone-like activity; Distal motor neuropathy Small heat shock proteins (sHsp) 2 form a ubiquitous and very diverse family of proteins [1]. All members of this fam- ily contain a conservative -crystallin domain consisting of 80–100 residues and several members of this family possess chaperone-like activity [2,3]. Ten members of this family are encoded in the human genome and some are expressed in tissues-dependent manner [4,5]. The protein with apparent molecular mass 22 kDa, belonging to the family of sHsp, is denoted as HSP22, HspB8 or H11 kinase [4–7]. Initially HSP22 was identiWed as an oncogene serine/threonine protein kinase [6,8], but later this suggestion was questioned [9–11]. Expression of HSP22 is increased in response to unfavorable conditions [12] and it possesses chaperone-like activity both in vitro [10,12] and in vivo [13,14]. It is supposed that HSP22 is involved in regu- lation of proliferation [15], myocardium hypertrophy [8], pro- tection of hibernating myocardium [16] and in the regulation of apoptosis [17]. Detailed mechanisms of HSP22 action remain unknown. However, as already mentioned, HSP22 possesses chaperone-like activity [10,12–14] and is able to interact with diVerent target proteins preventing their aggre- gation induced by misfolding or denaturation. Therefore depending on conditions HSP22 might reveal multiple eVects on diVerent processes in the cell. * Corresponding author. Fax: +7 495 939 2747. E-mail address: NBGusev@mail.ru (N.B. Gusev). 1 These authors equally contributed to this investigation. 2 Abbreviations used: ADH, yeast alcohol dehydrogenase; CD, circular dichroism; GuCl, guanidine hydrochloride; HSP22, human small heat shock protein with apparent molecular mass 22 kDa; K141E mutant of HSP22, mutant with replacement of Lys141 with glutamic acid; PMSF, phenylmethanesulfonyl Xuoride; sHsp, small heat shock protein(s); TPCK, tosyl-L-phenylalanine chloromethyl ketone.