The chaperone-like activity of a small heat shock protein is lost after sulfoxidation of conserved methionines in a surface-exposed amphipathic α-helix

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Abstract

The small heat shock proteins (sHsps) possess a chaperone-like activity which prevents aggregation of other proteins during transient heat or oxidative stress. The sHsps bind, onto their surface, molten globule forms of other proteins, thereby keeping them in a refolding competent state. In Hsp21, a chloroplast-located sHsp in all higher plants, there is a highly conserved region forming an amphipathic α-helix with several methionines on the hydrophobic side according to secondary structure prediction. This paper describes how sulfoxidation of the methionines in this amphipathic α-helix caused conformational changes and a reduction in the Hsp21 oligomer size, and a complete loss of the chaperone-like activity. Concomitantly, there was a loss of an outer-surface located α-helix as determined by limited proteolysis and circular dichroism spectroscopy. The present data indicate that the methionine-rich amphipathic α-helix, a motif of unknown physiological significance which evolved during the land plant evolution, is crucial for binding of substrate proteins and has rendered the chaperone-like activity of Hsp21 very dependent on the chloroplast redox state.

Detaljer

Författare
  • Ulrika Härndahl
  • Bas P.A. Kokke
  • Niklas Gustavsson
  • Sara Linse
  • Kristina Berggren
  • Folke Tjerneld
  • Wilbert C. Boelens
  • Cecilia Sundby
Enheter & grupper
Forskningsområden

Ämnesklassifikation (UKÄ) – OBLIGATORISK

  • Biologiska vetenskaper

Nyckelord

Originalspråkengelska
Sidor (från-till)227-237
TidskriftBBA - Protein Structure and Molecular Enzymology
Volym1545
Utgivningsnummer1-2
StatusPublished - 2001
PublikationskategoriForskning
Peer review utfördJa