Structure of proline 3-hydroxylase. Evolution of the family of 2-oxoglutarate
dependent oxygenases.
Eur J Biochem, 268 (24):
6625--6636 (December 2001)Abstract
Iron (II)/2-oxoglutarate (2-OG)-dependent oxygenases catalyse oxidative
reactions in a range of metabolic processes including the hydroxylation
of proline and lysine residues during the post-translational modification
of collagen. 2-OG oxygenases commonly require ascorbate for full
activity. In the vitamin C deficient disease, scurvy, reduced activity
of 2-OG oxygenases results in impaired formation of collagen. Here
we report the crystal structure of bacterial proline 3-hydroxylase
from Streptomyces sp., an enzyme which hydroxylates proline at position
3, the first of a 2-OG oxygenase catalysing oxidation of a free
alpha-amino acid. Structures were obtained for the enzyme in the
absence of iron (to 2.3A resolution, R=20.2%, Rfree=25.3%) and that
complexed to iron (II) (to 2.4A resolution, R=19.8%, Rfree=22.6%).
The structure contains conserved motifs present in other 2-OG oxygenases
including a 'jelly roll' beta strand core and residues binding iron
and 2-oxoglutarate, consistent with divergent evolution within the
extended family. The structure differs significantly from many other
2-OG oxygenases in possessing a discrete C-terminal helical domain.
Analysis of the structure suggests a model for proline binding and
a mechanism for uncoupling of proline and 2-OG turnover.