Specific Incorporation ofL-Glutamine into Volicitin in the Regurgitant ofSpodoptera litura

Abstract

Volicitin, [N-(17-hydroxylinolenoyl)-L-glutamine], was identified as an elicitor of plant volatiles from a Spodoptera exigua regurgitant. It has been proposed that gut microbes synthesize volicitin from glutamine, a predominant amino acid component in the insect gut. However, we found that glutamine was not a major component in the regurgitant of Spodoptera litura, although L-glutamine was exclusively incorporated into volicitin by S. litura fed on diets enriched with various amino acids. This selectivity of glutamine as a substrate was not due to a dominant occurrence in the insect gut.

Absolute Configuration of Volicitin from the Regurgitant of Lepidopteran Caterpillars and Biological Activity of Volicitin-Related Compounds

“…The conjugation of glutamine with fatty acids was demonstrated in vitro with S. litura gut tissues, 19) M. sexta gut enzyme, 20) and S. exigua gut microbes. 21) Yoshinaga et al have also reported that glutamine was exclusively incorporated into volicitin-related compounds in vivo 22) and suggested that the hydroxyl group was introduced after the conjugation of glutamine and fatty acids. Spiteller et al have implied that the hydroxylation on the 17th carbon chain might be carried out by the bacterial cytochrome P450 enzyme.…”

Generalist and specialist lepidopteran larvae elicit different transcriptional responses in Nicotiana attenuata, which correlate with larval FAC profiles

“…A recent analysis of S. litura regurgitate suggests that caterpillars can influence its FAC composition through the selective incorporation of glutamine independently of its dietary concentration (Yoshinaga et al. 2003).…”

Active role of fatty acid amino acid conjugates in nitrogen metabolism in Spodoptera litura larvae

“…The amino acid components of FACs appear to be restricted to glutamine and glutamic acid. Specific incorporation of glutamine into FACs was reported in Spodoptera litura (20), and a coupling enzyme for the glutamine conjugates has been isolated as a membrane-bound protein in gut tissues of M. sexta larvae (21) and in S. litura midgut tissues (22). Surprisingly, it is still not clear what benefit insects gain from FACs that outweighs the elicitation of strong defensive reactions in plants.…”