PR002285 (Project)

Description:We have previously demonstrated that the C. elegans pnp-1 gene encodes a purine nucleoside phosphorylase that catalyzes the conversion of inosine to hypoxanthine. We hypothesize that the C. elegans adah-1 gene encodes the adenosine deaminase that acts upstream of PNP-1 to produce inosine from adenosine. To investigate the hypothesis that ADAH-1 functions as a canonical adenosine deaminase, we used RNAi to knockdown expression of ADAH-1, and used LC-MS to compare relative levels of adenosine, inosine, and hypoxanthine in the knockdown animals and an RNAi control (L4440). As a control we also confirmed the activity of pnp-1, by comparing levels of adenosine, inosine, and hypoxanthine in control (N2) and the loss of function mutant pnp-1(jy90). As expected we found that levels of hypoxanthine were reduced and levels of inosine were increased in pnp-1 mutants relative to control. In contrast, RNAi against adah-1 led to significantly increased levels of adenosine, and decreased levels of inosine and the downstream metabolite hypoxanthine. We conclude that ADAH-1 is a bona fide adenosine deaminase.