Scientists from the Institute of Organic Chemistry and Biochemistry in Prague, Czech Republic, and from the Max Planck Institute for Chemical Ecology in Jena, Germany, studied the pheromone chemistry of moths and discovered a new evolutionary mechanism: a single amino acid residue in desaturases − enzymes that introduce double bonds, of the tobacco hornworm Manduca sexta (image) − switches the desaturase products from mono- and di-unsaturated to tri-unsaturated sex pheromone precursors. The susceptibility of desaturases to major shifts in their specificities, due to minor mutations, may significantly contribute to the divergence in moth pheromone communication and so lead to the evolution of new insect species. These results were published in the October 13, 2015 issue of PNAS. The article is titled “Evolution of Moth Sex Pheromone Composition by a Single Amino Acid Substitution in a Fatty Acid Desaturase.” Sex pheromones represent a diverse group of chemical compounds that are central to mate-finding behavior in insects and can be found across various life forms. In most moth species, females use species-specific sex pheromones consisting of volatile fatty acid derivatives to attract conspecific males over long distances. These pheromones are predominantly long-chain aliphatic acetates, alcohols, or aldehydes containing up to three carbon-carbon double bonds with variable configurations at various positions along the carbon backbone. Pheromone-biosynthetic fatty acid desaturases, enzymes that introduce double bonds at specific positions and configurations into fatty acyl pheromone precursors of various chain lengths, contribute significantly to the number of possible pheromone structures. To maintain an efficient chemical communication, the signal receiver must stay tuned to the signal producer.
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