Asparagine Hydroxylation of the HIF Transactivation Domain: A Hypoxic Switch
David Lando,1
Daniel J. Peet,1
Dean A. Whelan,2
Jeffrey J. Gorman,2
Murray L. Whitelaw1*
The hypoxia-inducible factors (HIFs) 1
and 2 are key
mammalian transcription factors that exhibit dramatic increases in both
protein stability and intrinsic transcriptional potency during low-oxygen stress. This increased stability is due to the absence of
proline hydroxylation, which in normoxia promotes binding of HIF to the
von Hippel-Lindau (VHL tumor suppressor) ubiquitin ligase. We
now show that hypoxic induction of the COOH-terminal transactivation
domain (CAD) of HIF occurs through abrogation of hydroxylation of a
conserved asparagine in the CAD. Inhibitors of Fe(II)- and
2-oxoglutarate-dependent dioxygenases prevented hydroxylation of the
Asn, thus allowing the CAD to interact with the p300 transcription
coactivator. Replacement of the conserved Asn by Ala resulted in
constitutive p300 interaction and strong transcriptional activity. Full
induction of HIF-1 and -2, therefore, relies on the abrogation of
both Pro and Asn hydroxylation, which during normoxia occur at the
degradation and COOH-terminal transactivation domains, respectively.
1 Department of Molecular Biosciences
(Biochemistry), Adelaide University, SA 5005, Australia.
2 CSIRO Health Sciences and Nutrition, 343 Royal
Parade, Parkville, VIC 3052, Australia.
*
To whom correspondence should be addressed. E-mail:
murray.whitelaw{at}adelaide.edu.au
