Cookies on this website

We use cookies to ensure that we give you the best experience on our website. If you click 'Accept all cookies' we'll assume that you are happy to receive all cookies and you won't see this message again. If you click 'Reject all non-essential cookies' only necessary cookies providing core functionality such as security, network management, and accessibility will be enabled. Click 'Find out more' for information on how to change your cookie settings.

Hypoxia-inducible factor (HIF) is a transcriptional complex that mediates a broad range of cellular and systemic responses to hypoxia. Analysis of HIF-alpha subunits has demonstrated that its activity is regulated by a series of oxygen-dependent enzymatic hydroxylations at specific prolyl and asparaginyl residues. Combined structural/genetic approaches have identified the relevant enzymes as members of the 2-oxoglutarate-dependent dioxygenase superfamily, possessing a beta-barrel 'jelly-roll' conformation that aligns a 2-histidine/1-carboxylate iron co-ordination motif at the catalytic centre. HIF prolyl hydroxylation is performed by a closely related set of isoenzymes (PHD1-3) that differ in abundance and subcellular localisation. Hydroxylation of either human HIF-1alpha Pro402 or Pro564 promotes interaction with the von Hippel-Lindau tumour suppressor protein (pVHL). In oxygenated cells this process targets HIF-alpha for rapid proteasomal destruction. HIF asparaginyl hydroxylation is performed by a protein termed factor inhibiting HIF (FIH). In oxygenated cells hydroxylation of human HIF-1alpha Asn803 prevents interaction with the p300 transcriptional co-activator, providing a second mechanism by which HIF-mediated transcription is inactivated. Genetic studies demonstrate a critical function for both types of enzyme in regulating the HIF transcriptional cascade. Limitation of activity in hypoxia supports a central role of these hydroxylases in cellular oxygen sensing. Regulation of the amount of hydroxylase protein, and the supply of other co-substrates and co-factors, particularly the cellular availability of iron, also contribute to tuning the physiological response to hypoxia.

Original publication




Conference paper

Publication Date





223 - 230


Animals, Cell Hypoxia, DNA-Binding Proteins, Humans, Hydroxylation, Hypoxia-Inducible Factor 1, Hypoxia-Inducible Factor 1, alpha Subunit, Nuclear Proteins, Oxygen, Transcription Factors