The pivotal role of the beta 7 strand in the intersubunit contacts of different human small heat shock proteins.
Human alpha B-crystallin and small heat shock proteins HspB6 and HspB8 were mutated so that all endogenous Cys residues were replaced by Ser and the single Cys residue was inserted in a position homologous to that of Cys137 of human HspB1, i.e. in a position presumably located in the central part of beta 7 strand of the alpha-crystallin domain. The secondary, tertiary, and quaternary structures of thus obtained Cys-mutants as well as their chaperone-like activity were similar to those of their wild-type counterparts. Mild oxidation of Cys-mutants leads to formation of disulfide bond crosslinking neighboring monomers thus indicating participation of the beta 7 strand in intersubunit interaction. Oxidation weakly affects the secondary and tertiary structure, does not affect the quaternary structure of alpha B-crystallin and HspB6, and shifts equilibrium between monomer and dimer of HspB8 towards dimer formation. It is concluded that the beta 7 strand participates in the intersubunit interaction of four human small heat shock proteins (alpha B-crystallin, HspB1, HspB6, HspB8) having different structure of beta2 strand of alpha-crystallin domain and different length and composition of variable N- and C-terminal tails.
Mymrikov
Evgeny V
EV
Department of Biochemistry, School of Biology, Moscow State University, Moscow, 119991, Russian Federation.
Bukach
Olesya V
OV
Seit-Nebi
Alim S
AS
Gusev
Nikolai B
NB
D019943:Amino Acid Substitution; D002942:Circular Dichroism; D003545:Cysteine / Q000737:chemistry; D050886:HSP20 Heat-Shock Proteins / Q000737:chemistry; D055551:HSP27 Heat-Shock Proteins / Q000737:chemistry; D006360:Heat-Shock Proteins / Q000737:chemistry; D050888:Heat-Shock Proteins, Small / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D018832:Molecular Chaperones; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry; D020836:Protein Structure, Quaternary; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D038203:alpha-Crystallin B Chain / Q000737:chemistry
D050886:HSP20 Heat-Shock Proteins; D055551:HSP27 Heat-Shock Proteins; C057725:HSPB1 protein, human; C494382:HSPB6 protein, human; C413214:HSPB8 protein, human; D006360:Heat-Shock Proteins; D050888:Heat-Shock Proteins, Small; D018832:Molecular Chaperones; D011994:Recombinant Proteins; D038203:alpha-Crystallin B Chain; D017346:Protein Serine-Threonine Kinases; D003545:Cysteine