Gustatory receptor 22e is essential for sensing chloroquine and strychnine in Drosophila melanogaster.

Chloroquine, an amino quinolone derivative commonly used as an anti-malarial drug, is known to impart an unpleasant taste. Little research has been done to study chloroquine taste in insects, therefore, we examined both the deterrant properties and mechanisms underlying chloroquine perception in fruit flies. We identified the antifeedant effect of chloroquine by screening 21 gustatory receptor (Grs) mutants through behavioral feeding assays and electrophysiology experiments. We discovered that two molecular sensors, GR22e and GR33a, act as chloroquine receptors, and found that chloroquine-mediated activation of GRNs occurs through S-type sensilla. At the same time, we successfully recapitulated the chloroquine receptor by expressing GR22e in ectopic gustatory receptor neurons. We also found that GR22e forms a part of the strychnine receptor. We suggest that the Drosophila strychnine receptor might have a very complex structure since five different GRs are required for strychnine-induced action potentials.

Continuous supply of glucose and glycerol enhances biotransformation of ricinoleic acid to (E)-11-(heptanoyloxy) undec-9-enoic acid in recombinant Escherichia coli.

This study aimed at the development of biotransformation strategies with feeding of energy sources for bioconversion of ricinoleic acid to (E)-11-(heptanoyloxy) undec-9-enoic acid (11-HOUA), a key intermediate of brassylic acid, by recombinant Escherichia coli overexpressing an alcohol dehydrogenase from Micrococcus luteus and a Baeyer-Villiger monooxygenase from Pseudomonas putida KT2440. Feeding of glucose or glycerol facilitated both the preparation of high-density cell biocatalyst and supply of the NAD+ and NADPH cofactors. By the glucose feeding strategy, 30.8g/L of the engineered E. coli cells produced 29.7mM of 11-HOUA with 1.9mM/h of productivity, which were 1.8 and 1.6 times higher than the same biotransformation without the glucose feeding, respectively. Intermittent addition of glycerol increased 11-HOUA productivity by 16% compared to that by the glucose feeding. Finally, 34.5mM of 11-HOUA concentration, 77% conversion and 2.2mM/h productivity were obtained using 31.6g/L of cell biocatalyst along with the glycerol addition. It was concluded that supplementation of additional carbon sources in biotransformation process would be a potent strategy to increase the performance of fatty acid conversion.