Polypharmacology translates between species and phylogenetic distance: A functional, bioinformatic, and structural study on organic anion transporting polypeptides.

Recently, we postulated the existence of 'multitarget binding sites', reoccurring structural motifs that interconnect otherwise structurally, functionally, and/or phylogenetically distant proteins. In this study, we functionally assessed a selection of 23 multitarget ATP-binding cassette (pan-ABC) transporter modulators against zebrafish (Danio rerio) organic anion transporting polypeptide (drOatp1d1), a transport protein of the solute carrier (SLC) superfamily. The zebrafish embryo is an important in vivo model in drug development to evaluate drug pharmacokinetics and pharmacodynamics. In total, 87.0 % of the compounds were identified as drOatp1d1 transport inhibitors, and the observed effects resembled the ones observed for human OATP1A2, OATP1B1, OATP1B3, and OATP2B1 despite the relative phylogenetic distance of drOatp1d1 to human OATPs. Potent hit molecules appeared to bind to a potential drOatp1d1 binding site derived from an OATP1B1 cryo-EM structure - strengthening the notion of common structural motifs between membrane transporters. The bioactivity of pranlukast (PRA) on human OATPs could be accurately predicted based on its activity on drOatp1d1. The collection of pan-ABC transporter modulators also showed activity against other zebrafish (i.e., drAbcb4) and non-zebrafish [i.e., murine Abca1 (mumAbca1)] membrane transporters, ultimately rendering it a suitable tool to translate between species to tackle the undruggability of membrane transporters and potentially other proteins by addressing conserved structural motifs.