title: Pressure activation of the chaperone function of small heat shock proteins.
abstract: Small heat shock proteins play an important role in the stress response of cells and in several other cellular functions. They possess chaperone-like activity; i.e. they can bind and protect damaged proteins from aggregation and maintain them in a folding-competent state. Two members of this family were investigated in this work: bovine alpha-crystallin and heat shock protein (HSP)16.5 from the thermophilic archaebacteria Methanococcus jannaschii. We reported earlier the enhancement of chaperone potency of alpha-crystallin by high pressure. We now report the completion of the work with results on HSP16.5. The chaperone potency of both proteins can be enhanced significantly by applying high pressure. Evidence by light scattering, Fourier transform infrared (FT-IR) and tryptophan fluorescence experiments show that while the secondary and tertiary structure of these proteins are not influenced by high pressure, their quatemary structure becomes affected: H bonds between subunits are weakened or broken, tryptophan environments become more polar, oligomers dissociate to some extent. We conclude that the oligomeric structure of both proteins is loosened, resulting in stronger dynamics and in more accessible hydrophobic surfaces. These properties lead to increased chaperone potency.
authors.affiliation: Institute for Biophysics and Radiation Biology, Semmelweis University, Budapest, Budapest, Hungary. tolgyesi@puskin.sote.hu
authors.forename: E
authors.initials: E
authors.lastname: Tölgyesi
authors.forename: C S
authors.initials: CS
authors.lastname: Böde
authors.forename: L
authors.initials: L
authors.lastname: Smelleri
authors.forename: D R
authors.initials: DR
authors.lastname: Kim
authors.forename: K K
authors.initials: KK
authors.lastname: Kim
authors.forename: K
authors.initials: K
authors.lastname: Heremans
authors.forename: J
authors.initials: J
authors.lastname: Fidy
mesh_terms: D000818:Animals; D019843:Archaeal Proteins / Q000737:chemistry* / Q000502:physiology; D002417:Cattle; D003459:Crystallins; D006360:Heat-Shock Proteins / Q000737:chemistry* / Q000502:physiology; D057927:Hydrophobic and Hydrophilic Interactions; D017017:Methanococcus / Q000737:chemistry; D018832:Molecular Chaperones / Q000737:chemistry / Q000502:physiology; D011312:Pressure; D020836:Protein Structure, Quaternary; D013057:Spectrum Analysis; D038201:alpha-Crystallins / Q000737:chemistry* / Q000502:physiology
chemical_list: D019843:Archaeal Proteins; D003459:Crystallins; C113795:HSP16.5 protein, Methanococcus jannaschii; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; D038201:alpha-Crystallins