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PLoS One

Title:		"Functional evolution of duplicated odorant-binding protein genes, Obp57d and Obp57e, in Drosophila"
Author(s):		Harada E; Nakagawa J; Asano T; Taoka M; Sorimachi H; Ito Y; Aigaki T; Matsuo T;
Address:		"Department of Biological Sciences, Tokyo Metropolitan University, Hachioji, Tokyo, Japan"
Journal Title:		PLoS One
Year:		2012
Volume:		20120106
Issue:		1
Page Number:		e29710 -
DOI:		10.1371/journal.pone.0029710
ISSN/ISBN:		1932-6203 (Electronic) 1932-6203 (Linking)
Abstract:		"Odorant-binding proteins (OBPs) are extracellular proteins found in insect chemosensilla, where they participate in the sensing of odors, tastes, and pheromones. Although a large number of OBP genes have been identified in insect genomes, their molecular functions and biological roles have been clarified in limited cases. Two OBP genes, Obp57d and Obp57e, were involved in the evolution of host-plant preference in Drosophila sechellia. Comparative analyses of the Obp57d/e genomic sequences from 27 closely related species suggested that the two genes arose by tandem gene duplication and functionally diverged from each other. In this study, the functional evolution of Obp57d and Obp57e was examined by in vitro binding assays using recombinant proteins synthesized in a bacterial system. Compared to the ancestral Dpse\OBP57de, Dmel\OBP57d was more specialized to tridecanoic acid while Dmel\OBP57e was generalized regarding their binding affinity, suggesting that the two OBP genes underwent subfunctionalization and neofunctionalization. A behavioral analysis using knockout flies supported that the biological role is different between OBP57d and OBP57e in vivo. Site-directed mutagenesis of the evolutionarily conserved amino acids revealed that these residues play an important role in protein folding. These findings provide a clue to understanding how the repertoire of OBP genes is maintained in a genome under natural selection"
Keywords:		"Amino Acid Sequence Animals Chemotaxis/genetics/physiology Drosophila/*genetics Drosophila Proteins/chemistry/*genetics/isolation & purification/metabolism Escherichia coli/genetics/metabolism *Evolution, Molecular Female Genes, Duplicate Molecular Sequen;"
Notes:		"MedlineHarada, Eriko Nakagawa, Jun Asano, Tsunaki Taoka, Masato Sorimachi, Hiroyuki Ito, Yoshihiro Aigaki, Toshiro Matsuo, Takashi eng Research Support, Non-U.S. Gov't 2012/01/13 PLoS One. 2012; 7(1):e29710. doi: 10.1371/journal.pone.0029710. Epub 2012 Jan 6"