These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: The chaperone-like activity of a small heat shock protein is lost after sulfoxidation of conserved methionines in a surface-exposed amphipathic alpha-helix.
    Author: Härndahl U, Kokke BP, Gustavsson N, Linse S, Berggren K, Tjerneld F, Boelens WC, Sundby C.
    Journal: Biochim Biophys Acta; 2001 Feb 09; 1545(1-2):227-37. PubMed ID: 11342048.
    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 alpha-helix with several methionines on the hydrophobic side according to secondary structure prediction. This paper describes how sulfoxidation of the methionines in this amphipathic alpha-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 alpha-helix as determined by limited proteolysis and circular dichroism spectroscopy. The present data indicate that the methionine-rich amphipathic alpha-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.
    [Abstract] [Full Text] [Related] [New Search]