1two
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(New page: 200px<br /><applet load="1two" size="450" color="white" frame="true" align="right" spinBox="true" caption="1two" /> '''NMR structure of the pheromone binding prote...)
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Revision as of 01:32, 21 November 2007
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NMR structure of the pheromone binding protein from Antheraea polyphemus at acidic pH
Overview
Olfaction in moths is one of the most impressive examples of chemical, communication found in nature for its exquisite sensitivity and, selectivity. Pheromone-binding proteins (PBPs), present in the antennae of, male moth and other insect species, bind the hydrophobic pheromone, molecules and transport them to the G protein-coupled olfactory receptor, proteins. The targeted delivery of these non-polar ligands to, membrane-bound receptors involves ligand release on or near the target, cell membranes, the molecular details of which are still not well, understood. The PBP from the giant silk moth Antheraea polyphemus, (ApolPBP) binds acetate pheromone only at pH above 6.0, and its structure, at pH 6.3 has been determined previously. Here we report the solution NMR, structure of ApolPBP at the acidic pH 5.2. Comparison of the present, structure to that at neutral pH reveals the details of the pH-induced, conformational changes and provides mechanistic clues for ligand release, at acidic pH. The ApolPBP pH-induced structural change is quite different, from that observed for alcohol binding Bombyx mori PBP (BmorPBP), where, the C-terminal segment folds into a helix and occupies the ligand binding, cavity. We observe a reorientation of helices alpha1, alpha3, and alpha4, at acidic pH caused by protonation of His69, His70 and His95 in the, interior. This provides the driving force behind the opening of the ligand, binding cavity and the release of the pheromone molecule from its carrier, protein near the membrane.
About this Structure
1TWO is a Single protein structure of sequence from Antheraea polyphemus. Full crystallographic information is available from OCA.
Reference
Structural consequences of the pH-induced conformational switch in A.polyphemus pheromone-binding protein: mechanisms of ligand release., Zubkov S, Gronenborn AM, Byeon IJ, Mohanty S, J Mol Biol. 2005 Dec 16;354(5):1081-90. Epub 2005 Oct 27. PMID:16289114
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