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Proceedings Paper

Conformational flexibility of domain III of annexin V: the effect of pH and binding to membrane-water interfaces
Author(s): Jana Sopkova; Michel Vincent; Maza Takahashi; Anita Lewit-Bentley; Jacques Gallay
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Paper Abstract

Steady-state and time-resolved fluorescence of the single tryptophan residue (W187) of annexin V show that the conformation and the dynamics of domain III are strongly modified upon binding of the protein to negatively charged phospholipid vesicles in the presence of calcium, or upon incorporation into reverse micelles of water/sodium bis(2- ethylhexyl) sulfosuccinate (AOT) in iso-octane. In the protein at neutral pH, W187 is slightly mobile and buried in a hydrophobic pocket. It becomes more mobile and is moved in a more polar environment when the protein interacts with the model membranes. In each condition, the heterogeneity of the fluorescence intensity decay of W187 is likely due to the co- existence of local conformers with different dynamics. A similar change of conformation and dynamics can be provoked by mild acidic pH. This suggests that electrostatic interactions are important for the folding of domain III. An interplay of salt bridges implying charged amino-acid side-chains at the protein surface in domain III can be observed in the crystal structure. Local pH modifications at the membrane surface can therefore be responsible for the observed conformational change. The high flexibility of domain III in the membrane- bound protein suggests moreover that this domain may not be crucial for the interaction of the protein with the membrane, in agreement with recent atomic force microscope results (Reviakine et al., 1998, J. Struct. Biol. 121, 356-362).

Paper Details

Date Published: 3 May 1999
PDF: 13 pages
Proc. SPIE 3602, Advances in Fluorescence Sensing Technology IV, (3 May 1999); doi: 10.1117/12.347513
Show Author Affiliations
Jana Sopkova, Univ. de Paris-Sud (France)
Michel Vincent, Univ. de Paris-Sud (France)
Maza Takahashi, Institut Curie and CNRS (France)
Anita Lewit-Bentley, Univ. de Paris-Sud (France)
Jacques Gallay, Univ. de Paris-Sud (France)

Published in SPIE Proceedings Vol. 3602:
Advances in Fluorescence Sensing Technology IV
Joseph R. Lakowicz; Steven A. Soper; Richard B. Thompson, Editor(s)

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