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Proc Natl Acad Sci U S A

Title:		Pheromone discrimination by a pH-tuned polymorphism of the Bombyx mori pheromone-binding protein
Author(s):		Damberger FF; Michel E; Ishida Y; Leal WS; Wuthrich K;
Address:		"Institute of Molecular Biology and Biophysics, Eidgenossische Technische Hochschule Zurich, CH-8093 Zurich, Switzerland"
Journal Title:		Proc Natl Acad Sci U S A
Year:		2013
Volume:		20131024
Issue:		46
Page Number:		18680 - 18685
DOI:		10.1073/pnas.1317706110
ISSN/ISBN:		1091-6490 (Electronic) 0027-8424 (Print) 0027-8424 (Linking)
Abstract:		"The Bombyx mori pheromone-binding protein (BmorPBP) is known to adopt two different conformations. These are BmorPBP(A), where a regular helix formed by the C-terminal dodecapeptide segment, alpha7, occupies the ligand-binding cavity, and BmorPBP(B), where the binding site is free to accept ligands. NMR spectra of delipidated BmorPBP solutions at the physiological pH of the bulk sensillum lymph near pH 6.5 show only BmorPBP(A), and in mixtures, the two species are in slow exchange on the chemical shift frequency scale. This equilibrium has been monitored at variable pH and ligand concentrations, demonstrating that it is an intrinsic property of BmorPBP that is strongly affected by pH variation and ligand binding. This polymorphism tunes BmorPBP for optimal selective pheromone transport: Competition between alpha7 and lipophilic ligands for its binding cavity enables selective uptake of bombykol at the pore endings in the sensillum wall, whereas compounds with lower binding affinity can only be bound in the bulk sensillum lymph. After transport across the bulk sensillum lymph into the lower pH area near the dendritic membrane surface, bombykol is ejected near the receptor, whereas compounds with lower binding affinity are ejected before reaching the olfactory receptor, rendering them susceptible to degradation by enzymes present in the sensillum lymph"
Keywords:		Animals Biological Transport/physiology Bombyx/*metabolism/physiology Carrier Proteins/*chemistry/genetics/*metabolism Fatty Alcohols/metabolism Hydrogen-Ion Concentration Insect Proteins/*chemistry/genetics/*metabolism Intercellular Signaling Peptides an;
Notes:		"MedlineDamberger, Fred F Michel, Erich Ishida, Yuko Leal, Walter S Wuthrich, Kurt eng Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, Non-P.H.S. 2013/10/26 Proc Natl Acad Sci U S A. 2013 Nov 12; 110(46):18680-5. doi: 10.1073/pnas.1317706110. Epub 2013 Oct 24"