Deficiency in pyruvate kinase disrupts glucose and nitrogen metabolism in Aedes aegypti females

Recently, the three-dimensional structure and kinetic properties of recombinant Aedes aegypti pyruvate kinase 1 (AaPK1) were reported. The unique regulatory property of AaPK1 observed in in vitro assays encouraged us to study the enzyme in vivo, using several techniques including RNA interference (RNAi), high-resolution, accurate-mass (HRAM) liquid chromatography-mass spectrometry (HRAM-LC/MS) and HRAM ion chromatography-mass spectrometry (HRAM-IC/MS) methods. We found that survival of PK-deficient mosquitoes is dependent on whether females are maintained on sucrose, water, blood/sucrose or blood/water diets. Depletion of PK by RNAi increased transcript levels of several genes that encode enzymes involved in both glucose and nitrogen metabolism. Furthermore, PK deficiency affected the abundance of the majority of the metabolites monitored in dsRNA-injected females fed a blood meal supplemented with [1,2-¹³C₂]-glucose. The metabolites of glycolysis and pentose phosphate pathway exhibited the most pronounced decrease compared to the control, more than 5-fold for glucose-6-phosphate and fructose-6-phosphate, and about 3-fold for pyruvate and lactate, all of them mainly in the [¹³C₂]-isotopologs. In all the other groups examined, amino acids, Krebs cycle and uric acid, the [¹³C₁]-isotopolog declines (approximately 2-fold) were also observed usually together with a decline in the [¹³C₂]-isotopolog. These data reveal how genetic knockdown of PK significantly impacts both carbon and nitrogen metabolism in mosquitoes. Taken together, our findings contribute to uncover a regulatory role of PK in the carbon and nitrogen metabolism of the arbovirus vector A. aegypti.