title: Quaternary structure of human small heat shock protein HSPB6 (Hsp20) in crowded media modeled by trimethylamine N-oxide (TMAO): Effect of protein phosphorylation.
abstract: Effect of trimethylamine N-oxide (TMAO), well-known osmolyte, widely used to imitate crowded intracellular conditions, on the quaternary structure of recombinant human small heat shock protein HspB6 (Hsp20) was analyzed by means of size-exclusion chromatography, chemical crosslinking and analytical ultracentrifugation. Consistent with previous reports, in the absence of TMAO unphosphorylated, pseudophosphorylated (S16D mutant) and phosphorylated HspB6 form only small oligomers (presumably dimers). Addition of TMAO to unphosphorylated HspB6 leads to formation of different large oligomers being in equilibrium with dimers. Pseudophosphorylation (S16D mutation) or phosphorylation partially or completely prevent TMAO-induced oligomerization of HspB6. Pseudophosphorylation affects bis-ANS binding suggesting decreased hydrophobicity of HspB6. According to size-exclusion chromatography, TMAO-induced changes of HspB6 oligomerization result in its altered interaction with HspB1 and this effect can be reversed by HspB6 phosphorylation. It is concluded that under conditions of molecular crowding, characteristic for intracellular environment, HspB6 undergoes reversible changes of its oligomeric state which can affect its physiologically important properties and can be delicately regulated by phosphorylation.
authors.affiliation: A. N. Bach Institute of Biochemistry, Russian Academy of Sciences, Leninsky Prospect 33, Moscow 119071, Russian Federation.
authors.forename: Nikolai N
authors.initials: NN
authors.lastname: Sluchanko
authors.affiliation: A. N. Bach Institute of Biochemistry, Russian Academy of Sciences, Leninsky Prospect 33, Moscow 119071, Russian Federation.
authors.forename: Natalia A
authors.initials: NA
authors.lastname: Chebotareva
authors.affiliation: Department of Biochemistry, School of Biology, Moscow State University, Moscow 119991, Russian Federation. Electronic address: NBGusev@mail.ru.
authors.forename: Nikolai B
authors.initials: NB
authors.lastname: Gusev
mesh_terms: D050886:HSP20 Heat-Shock Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D055551:HSP27 Heat-Shock Proteins / Q000378:metabolism; D006360:Heat-Shock Proteins; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D008744:Methylamines / Q000737:chemistry / Q000494:pharmacology*; D018832:Molecular Chaperones; D009154:Mutation; D010766:Phosphorylation; D020836:Protein Structure, Quaternary / Q000187:drug effects
chemical_list: D050886:HSP20 Heat-Shock Proteins; D055551:HSP27 Heat-Shock Proteins; C057725:HSPB1 protein, human; C494382:HSPB6 protein, human; D006360:Heat-Shock Proteins; D008744:Methylamines; D018832:Molecular Chaperones; C005855:trimethyloxamine
keywords: Crowding agents; Heterooligomeric complexes; Phosphorylation; Quaternary structure; Self-association; Small heat shock proteins