Factor Inhibiting HIF catalyses two asparaginyl-hydroxylations in VNVN motifs of ankyrin proteins

The aspariginyl-hydroxylase activity of Factor Inhibiting HIF (FIH) is a key regulator of the transcriptional activity of the hypoxia inducible factor. FIH also catalyses the hydroxylation of asparaginyl- and other-residues in ankyrin repeat domain (ARD) containing proteins, including Apoptosis stimulating of p53 (ASPP) protein family members. ASPP2 is reported to undergo a single FIH catalysed hydroxylation at Asn-986. We report biochemical and crystallographic evidence showing FIH can catalyse the unprecedented post-translational hydroxylation of both asparaginyl-residues in “VNVN” and related motifs of ankyrin repeat domains in apoptosis-stimulating of p53 (ASPP) proteins (i.e. ASPP1, ASPP2 and iASPP) and the related ASB11 and p18-INK4C proteins. The results extend the substrate scope of FIH catalysis and may have implications for its role in the hypoxic response and, ASPP protein function.