4Y8W

Crystal Structure of Human Cytochrome P450 21A2 Progesterone Complex

Summary for 4Y8W

• Entry DOI: 10.2210/pdb4y8w/pdb
• Descriptor: Cytochrome P450 21-hydroxylase, SULFATE ION, PROTOPORPHYRIN IX CONTAINING FE, ... (5 entities in total)
• Functional Keywords: steroid hydroxylation, monooxygenases, adrenal steroidogenesis, congenital adrenal hyperplasia, addison's disease, kinetic isotope effects, oxidoreductase
• Biological source: Homo sapiens (Human)
• Total number of polymer chains: 3
• Total formula weight: 166794.58

Authors

Pallan, P.S.,Lei, L.,Egli, M. (deposition date: 2015-02-16, release date: 2015-04-15, Last modification date: 2023-09-27)

Primary citation

Pallan, P.S.,Wang, C.,Lei, L.,Yoshimoto, F.K.,Auchus, R.J.,Waterman, M.R.,Guengerich, F.P.,Egli, M.
Human Cytochrome P450 21A2, the Major Steroid 21-Hydroxylase: STRUCTURE OF THE ENZYMEPROGESTERONE SUBSTRATE COMPLEX AND RATE-LIMITING C-H BOND CLEAVAGE.
J.Biol.Chem., 290:13128-13143, 2015

PubMed Abstract: Cytochrome P450 (P450) 21A2 is the major steroid 21-hydroxylase, and deficiency of this enzyme is involved in ∼95% of cases of human congenital adrenal hyperplasia, a disorder of adrenal steroidogenesis. A structure of the bovine enzyme that we published previously (Zhao, B., Lei, L., Kagawa, N., Sundaramoorthy, M., Banerjee, S., Nagy, L. D., Guengerich, F. P., and Waterman, M. R. (2012) Three-dimensional structure of steroid 21-hydroxylase (cytochrome P450 21A2) with two substrates reveals locations of disease-associated variants. J. Biol. Chem. 287, 10613-10622), containing two molecules of the substrate 17α-hydroxyprogesterone, has been used as a template for understanding genetic deficiencies. We have now obtained a crystal structure of human P450 21A2 in complex with progesterone, a substrate in adrenal 21-hydroxylation. Substrate binding and release were fast for human P450 21A2 with both substrates, and pre-steady-state kinetics showed a partial burst but only with progesterone as substrate and not 17α-hydroxyprogesterone. High intermolecular non-competitive kinetic deuterium isotope effects on both kcat and kcat/Km, from 5 to 11, were observed with both substrates, indicative of rate-limiting C-H bond cleavage and suggesting that the juxtaposition of the C21 carbon in the active site is critical for efficient oxidation. The estimated rate of binding of the substrate progesterone (kon 2.4 × 10(7) M(-1) s(-1)) is only ∼2-fold greater than the catalytic efficiency (kcat/Km = 1.3 × 10(7) M(-1) s(-1)) with this substrate, suggesting that the rate of substrate binding may also be partially rate-limiting. The structure of the human P450 21A2-substrate complex provides direct insight into mechanistic effects of genetic variants.

PubMed: 25855791
DOI: 10.1074/jbc.M115.646307

Experimental method

X-RAY DIFFRACTION (2.64 Å)