TAILIEUCHUNG - Báo cáo khoa học: Effect of mutations in the b5–b7 loop on the structure and properties of human small heat shock protein HSP22 (HspB8, H11)

The human genome encodes ten different small heat shock proteins, each of which contains the so-called a-crystallin domain consisting of 80– 100 residues and located in the C-terminal part of the molecule. The a-crystallin domain consists of six or sevenb-strands connected by different size loops and combined in twob-sheets. | ễFEBS Journal Effect of mutations in the p5-p7 loop on the structure and properties of human small heat shock protein HSP22 HspB8 H11 Alexei S. Kasakov1 z Olesya V. Bukach1 z Alim S. Seit-Nebi1 Steven B. Marston2 and Nikolai B. Gusev1 1 Department of Biochemistry Schoolof Biology Moscow State University Russia 2 NationalHeart and Lung Institute ImperialCollege London UK Keywords chaperone-like activity intrinsically disordered regions oligomeric structure small heat shock proteins Correspondence N. B. Gusev Department of Biochemistry Schoolof Biology Moscow State University Moscow 119991 Russia Fax Tel 7 495 939 2747 E-mail nbgusev@ These authors contributed equally to this work Received 17 June 2007 revised 30 July 2007 accepted 3 September 2007 doi The human genome encodes ten different small heat shock proteins each of which contains the so-called a-crystallin domain consisting of 80100 residues and located in the C-terminal part of the molecule. The a-crystallin domain consists of six or seven b-strands connected by different size loops and combined in two b-sheets. Mutations in the loop connecting the b5 and b7 strands and conservative residues of b7 in aA- aB-crystallin and HSP27 correlate with the development of different congenital diseases. To understand the role of this part of molecule in the structure and function of small heat shock proteins we mutated two highly conservative residues K137 and K141 of human HSP22 and investigated the properties of the K137E and K137 141E mutants. These mutations lead to a decrease in intrinsic Trp fluorescence and the double mutation decreased fluorescence resonance energy transfer from Trp to bis-ANS bound to HSP22. Mutations K137E and especially K137 141E lead to an increase in unordered structure in HSP22 and increased susceptibility to trypsinolysis. Both mutations decreased the probability of dissociation of small oligomers of HSP22 and mutation K137E increased the .

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