4NKY

Human steroidogenic cytochrome P450 17A1 mutant A105L with substrate 17alpha-hydroxyprogesterone

Summary for 4NKY

• Entry DOI: 10.2210/pdb4nky/pdb
• Related: 3RUK 3SWZ 4NKV 4NKW 4NKX 4NKZ
• Descriptor: Steroid 17-alpha-hydroxylase/17,20 lyase, PROTOPORPHYRIN IX CONTAINING FE, (9beta)-17-hydroxypregn-4-ene-3,20-dione, ... (4 entities in total)
• Functional Keywords: heme protein, monooxygenase, steroid 17alpha-hydroxylase, steroid c17, 20 lyase, nadph-cytochrome p450 reductase, cytochrome b5, endoplasmic reticulum membrane, oxidoreductase, lyase
• Biological source: Homo sapiens (human)
• Cellular location: Membrane : P05093
• Total number of polymer chains: 4
• Total formula weight: 226916.68

Authors

Scott, E.E.,Petrunak, E.M. (deposition date: 2013-11-13, release date: 2014-10-22, Last modification date: 2023-09-20)

Primary citation

Petrunak, E.M.,DeVore, N.M.,Porubsky, P.R.,Scott, E.E.
Structures of Human Steroidogenic Cytochrome P450 17A1 with Substrates.
J.Biol.Chem., 289:32952-32964, 2014

PubMed Abstract: The human cytochrome P450 17A1 (CYP17A1) enzyme operates at a key juncture of human steroidogenesis, controlling the levels of mineralocorticoids influencing blood pressure, glucocorticoids involved in immune and stress responses, and androgens and estrogens involved in development and homeostasis of reproductive tissues. Understanding CYP17A1 multifunctional biochemistry is thus integral to treating prostate and breast cancer, subfertility, blood pressure, and other diseases. CYP17A1 structures with all four physiologically relevant steroid substrates suggest answers to four fundamental aspects of CYP17A1 function. First, all substrates bind in a similar overall orientation, rising ∼60° with respect to the heme. Second, both hydroxylase substrates pregnenolone and progesterone hydrogen bond to Asn(202) in orientations consistent with production of 17α-hydroxy major metabolites, but functional and structural evidence for an A105L mutation suggests that a minor conformation may yield the minor 16α-hydroxyprogesterone metabolite. Third, substrate specificity of the subsequent 17,20-lyase reaction may be explained by variation in substrate height above the heme. Although 17α-hydroxyprogesterone is only observed farther from the catalytic iron, 17α-hydroxypregnenolone is also observed closer to the heme. In conjunction with spectroscopic evidence, this suggests that only 17α-hydroxypregnenolone approaches and interacts with the proximal oxygen of the catalytic iron-peroxy intermediate, yielding efficient production of dehydroepiandrosterone as the key intermediate in human testosterone and estrogen synthesis. Fourth, differential positioning of 17α-hydroxypregnenolone offers a mechanism whereby allosteric binding of cytochrome b5 might selectively enhance the lyase reaction. In aggregate, these structures provide a structural basis for understanding multiple key reactions at the heart of human steroidogenesis.

PubMed: 25301938
DOI: 10.1074/jbc.M114.610998

Experimental method

X-RAY DIFFRACTION (2.55 Å)