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Etude par Résonance Magnétique Nucléaire de macromolécules biologiques: structure, dynamique et interactions. Application à une protéine de liaison aux odeurs

Abstract : ASP2 is a 123-amino-acid odorant-binding protein (OBP) from the honeybee. The transport of airborne, hydrophobic odorants and pheromones through the sensillum lymph is thought to be accomplished by OBPs. The structure of the complex of ASP2 with TSP (trim�ethylesilylpropionate-d4) was solved by nuclear magnetic resonance. The structure is monomeric and well-defined (rmsd<1A), apart from residues D30 to S45. The overall fold of ASP2 is roughly conical, with four antiparallel helices a1 and a4-6 converging to a point and enclosing a highly hydrophobic and weakly polar pocket, with the opposite side capped by a fifth helix a3. Residues D30 to S45 undergo an original dynamical behavior: segment D30 to A38 is conformationally disordered in millisecond-timescale exchange whereas backbone from A37 to S45 is highly mobile in the pico-nanosecond range. The global correlation time is consistent with a monomeric protein. The ASP2 apoprotein is present under two stable forms whose conformations are very similar to the structure of the complex. Their relative populations are pH-dependent. Upon binding, one conformation is selected. The odorant IBMP (2-isobutyl-3-m�ethoxy-pyrazin) binds to ASP2 hydrophobic pocket with two orientations of similar affinity, in a head-to-foot fashion. Furthermore, the binding cavity adapts to the size of the ligand. Functional considerations are discussed.
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https://tel.archives-ouvertes.fr/tel-00006777
Contributor : Ewen Lescop <>
Submitted on : Tuesday, August 31, 2004 - 6:36:14 AM
Last modification on : Monday, June 22, 2020 - 12:08:07 PM
Long-term archiving on: : Friday, April 2, 2010 - 9:05:41 PM

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  • HAL Id : tel-00006777, version 1

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Ewen Lescop. Etude par Résonance Magnétique Nucléaire de macromolécules biologiques: structure, dynamique et interactions. Application à une protéine de liaison aux odeurs. Biochimie [q-bio.BM]. Université Paris Sud - Paris XI, 2003. Français. ⟨tel-00006777⟩

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