Structures of Human Steroidogenic Cytochrome P450 17A1 with Substrates

Petrunak, E.M.; DeVore, Natasha M.; Porubsky, Patrick; Scott, Emily E.

doi:10.1074/jbc.m114.610998

Cited by 112 publications

(190 citation statements)

References 53 publications

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“…One possibility is that the ⌬ 5 substrate (17␣-hydroxypregnenolone) 3-hydroxy group exchanges with deuterium and that this has an effect on the juxtaposition of the substrate in the active site. The hydroxyl moiety has been shown by Scott and coworkers (73,76) to be in hydrogen bonding distance to Asn-202 of human P450 17A1. A substitution of the 3-hydroxyl group by deuteration (i.e.…”

Section: B Ring Hydroxylation Of 16␣17␣-dihydroxyprogesterone By P45mentioning

confidence: 99%

“…Additionally, the 17-oxygen of 17␣-hydroxyprogesterone was directed at the ␤-face of 16␣,17␣-dihydroxyprogesterone. The 3-oxo group of 17␣-hydroxyprogesterone has been shown to hydrogen bond to Asn-202 of P450 17A1 in the crystal structure (73). Based on our observations with 6␤-hydroxylation of 16␣,17␣-dihydroxyprogesterone by P450 17A1 and the overlay of the two different substrates, we reason that the 16␣-hydroxy group of 16␣,17␣-dihydroxyprogesterone hydrogen bonds to Asn-202 of P450 17A1, which in turn directs the 6␤-hydrogen to the active iron center of the enzyme.…”

Section: B Ring Hydroxylation Of 16␣17␣-dihydroxyprogesterone By P45mentioning

confidence: 99%

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Mechanism of 17α,20-Lyase and New Hydroxylation Reactions of Human Cytochrome P450 17A1

Yoshimoto

Gonzalez

Auchus

et al. 2016

Journal of Biological Chemistry

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We propose three mechanisms that can involve the FeO 3؉ entity and that explain the 18 O label in the acetic acid, two involving the intermediacy of an acetyl radical and one a steroid 17,20-dioxetane. P450 17A1 was found to perform 16-hydroxylation reactions on its 17␣-hydroxylated products to yield 16,17␣-dihydroxypregnenolone and progesterone, suggesting the presence of an active perferryloxo active species of P450 17A1 when its lyase substrate is bound. The 6␤-hydroxylation of 16␣,17␣-dihydroxyprogesterone and the oxidation of both 16␣,17␣-dihydroxyprogesterone and 16␣,17␣-dihydroxypregnenolone to 16-hydroxy lyase products were also observed. We provide evidence for the contribution of a compound I mechanism, although contribution of a ferric peroxide pathway in the 17␣,20-lyase reaction cannot be excluded. Cytochrome P450 (P450)3 enzymes catalyze oxidations of more chemicals than any other group of proteins (1). The list of reactions includes aliphatic and aromatic hydroxylations, heteroatom oxidations, epoxidations, and reactions involving both ring formation and cleavage (2-4). Many P450 reactions are important in the biosynthesis and degradation of steroids and sterols (4, 5), including several critical C-C bond cleavage reactions, i.e. those catalyzed by P450s 11A1, 17A1 (Fig. 1), 19A1, and 51A1 (6, 7).The mechanisms of the C-C cleavage reactions have been the subject of considerable interest and debate. One of the questions with P450s 17A1, 19A1, and 51A1 has been whether the active oxidant is a ferric peroxide (FeO 2 Ϫ ), which is an early intermediate following oxygen addition to the iron (Fig. 2, step 4) or the FeO 3ϩ species (Fig. 2, step 6), often referred to as compound I (4, 10, 11). With P450s 17A1 and 19A1, a variety of approaches has been applied, including theoretical calculations, biomimetic models, spectroscopy, substrate atom labeling, and kinetics (12-32).These C-C bond cleavage reactions are complex, and many of the results are ambiguous; also, a "mixed" mechanism would not be discerned in many of these experiments. One powerful approach originally used by Akhtar and co-workers (27-31) analyzes the actual reaction and can provide discrimination between the nucleophilic FeO 2 Ϫ and electrophilic FeO 3ϩ reactions (Fig. 2), based on the incorporation of 18 O label from O 2 into the carboxylic acid products (Fig. 3) (7). However, these experiments are complicated due to the ubiquitous presence of formic acid (P450 19A1 and 51A1 reactions) and acetic acid (P450 17A1) in laboratory settings. Thus, the data from such experiments are interpreted with the most confidence when the steroid substrates are labeled with 2 H or 13 C isotopes to facilitate analysis (15,33). Even then, the mass spectrometry results can be problematic, particularly if a shift of only one atomic mass unit is introduced and isotopologues derived from 18 O incorporation are not discriminated from molecules containing natural abundance 13 C atoms (33). The incorporation of one atom of 18 O label from O 2 into formic acid (F...

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Section: B Ring Hydroxylation Of 16␣17␣-dihydroxyprogesterone By P45mentioning

confidence: 99%

Section: B Ring Hydroxylation Of 16␣17␣-dihydroxyprogesterone By P45mentioning

confidence: 99%

Mechanism of 17α,20-Lyase and New Hydroxylation Reactions of Human Cytochrome P450 17A1

Yoshimoto

Gonzalez

Auchus

et al. 2016

Journal of Biological Chemistry

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“…13). Interestingly, in the crystal structures of human P450 17A1 with 17␣-OH pregnenolone and 17␣-OH progesterone, the latter substrate still forms the H-bond to Asn-202, whereas 17␣-OH pregnenolone was found in two orientations (8). In one orientation, the H-bond between the hydroxyl group at C3 and Asn-202 is maintained, but in the other orientation the contact is severed, and the substrate for the lyase moved closer to the iron and the (putative) catalytic peroxy intermediate.…”

Section: Discussionmentioning

confidence: 99%

“…Crystal structures of human P450 17A1 have been published with the inhibitor abiraterone bound (5) and, more recently, with the steroid substrates (8). However, the biochemical basis of the second oxidation step remains enigmatic.…”

mentioning

confidence: 99%

Structural and Kinetic Basis of Steroid 17α,20-Lyase Activity in Teleost Fish Cytochrome P450 17A1 and Its Absence in Cytochrome P450 17A2

Pallan

Nagy

Lei

et al. 2015

Journal of Biological Chemistry

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Background: Fish (and human) P450 17A1 catalyze both steroid 17␣-hydroxylation and 17␣,20-lyase reactions. A second fish P450, 17A2 (51% identical), catalyzes only 17␣-hydroxylation. Results: Crystal structures of zebrafish P450 17A1 and 17A2 and human P450 17A1 are very similar. Conclusion: In kinetic analysis, the two-step oxidation of progesterone is more distributive than for pregnenolone. Significance: Small structural differences are associated with activities of the two fish P450s.

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“…Each substrate is aligned in a position that allows the formation of a hydrogen bond with the Asn202 side chain. The 17α-hydroxypregnenolone, a substrate of lyase activity, could also assume a second pose, that is closer to the catalytic iron and further away for Asn202, hence preventing the formation of a hydrogen bond as observed in the first position [33] . This observation could explain the substrate selectivity of the lyase reaction and the increased 17,20-lyase activity after the allosteric binding of cytochrome b5.…”

Section: Cyp17a1mentioning

confidence: 99%

Androgen-AR axis in primary and metastatic prostate cancer: chasing steroidogenic enzymes for therapeutic intervention

Pippione¹,

Boschi²,

Pors³

et al. 2017

JCMT

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Androgens play an important role in prostate cancer (PCa) development and progression. Although androgen deprivation therapy remains the front-line treatment for advanced prostate cancer, patients eventually relapse with the lethal form of the disease. The prostate tumor microenvironment is characterised by elevated tissue androgens that are capable of activating the androgen receptor (AR). Inhibiting the steroidogenic enzymes that play vital roles in the biosynthesis of testosterone (T) and dihydrotestosterone (DHT) seems to be an attractive strategy for PCa therapies. Emerging data suggest a role for the enzymes mediating pre-receptor control of T and DHT biosynthesis by alternative pathways in controlling intratumoral androgen levels, and thereby influencing PCa progression. This supports the idea for the development of multi-targeting strategies, involving both dual and multiple inhibitors of androgen-metabolising enzymes that are able to affect androgen synthesis and signalling at different points in the biosynthesis. In this review, we will focus on CYP17A1, AKR1C3, HSD17B3 and SRD5A, as these enzymes play essential roles in all the three androgenic pathways. We will review also the AR as an additional target for the design of bifunctional drugs. Targeting intracrine androgens and AKR1C3 have potential to overcome enzalutamide and abiraterone resistance and improve survival of advanced prostate cancer patients.

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Structures of Human Steroidogenic Cytochrome P450 17A1 with Substrates

Cited by 112 publications

References 53 publications

Mechanism of 17α,20-Lyase and New Hydroxylation Reactions of Human Cytochrome P450 17A1

Mechanism of 17α,20-Lyase and New Hydroxylation Reactions of Human Cytochrome P450 17A1

Structural and Kinetic Basis of Steroid 17α,20-Lyase Activity in Teleost Fish Cytochrome P450 17A1 and Its Absence in Cytochrome P450 17A2

Androgen-AR axis in primary and metastatic prostate cancer: chasing steroidogenic enzymes for therapeutic intervention

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