Lack of single amino acids transcriptionally tunes sensory systems to enhance microbiota intake

Maintaining sufficient levels of Amino acids (AAs) from the diet is essential for the organism to maintain protein translation and other metabolic processes. Amazingly, the removal of even a single eAA from the diet is sufficient to induce an increase of proteinaceous food intake in Drosophila melanogaster. This process of turning a physiological “need” for any eAA into a psychological “want” driving proteinaceous-food search and consumption still remains poorly understood. Moreover, dietary manipulations of different eAAs have varying effects on metabolism and physiology which depend on the specific eAA depleted. Thus, a systemic analysis of single eAAs effects on the organism is needed. To achieve that, we sequenced RNA from fly heads following exposure to diets depleted of single AAs. We found that depletion of eAAs had different impacts on transcription, however a significant number of regulated transcripts were shared across deprivations, indicating common mechanisms of response to deprivation. Surprisingly chemosensory receptor genes were found amongst the consistently diet-modulated genes, in spite of minimal, if any, change in sensory environment. Genetic manipulations of Or92a confirm its importance for the acceptance of the appropriate food sources, namely , yeast. While Ir76a governs approaches to specific gut bacteria. These results expand the idea that metabolic-internal state can alter sensory processing already at the transcriptional level, regardless of the sensory environment. Our work uncovers common and unique transcriptional changes induced by all eAA deprivations and reveals novel mechanisms underlying the organism's behavioral and physiological response to dietary challenges. Overall design: Each sample is obtained from 10 fly-heads following 3 days on full holidic medium diet or a diet lacking a single eAA