ReviewStructural control of cytochrome P450-catalyzed ω-hydroxylation
Research highlights
► Cytochrome P450 enzymes catalyze the ω-hydroxylation of unactivated hydrocarbon bonds. ► Hydroxylation is a difficult reaction that must be actively promoted by the enzyme. ► Cytochrome P450 enforces ω-hydroxylation by steric rather than electronic means.
Section snippets
Hydrocarbon ω-hydroxylation
In chemical terms, the regio- and stereoselective oxidation of unactivated hydrocarbon C–H bonds to the corresponding hydroxy (C–OH) products is the most difficult reaction catalyzed by cytochrome P450 enzymes. This substrate hydroxylation reaction is mediated by the “Compound I”-like ferryl species formed during the catalytic turnover of P450 enzymes. The Fe(IV) heme iron atom in this ferryl species is paired with a radical cation delocalized over the heme porphyrin ring, so the enzyme is two
Hydrocarbons
Bacterial P450 enzymes are known to oxidize linear hydrocarbons of C5–C15 chain lengths [11]. CYP153A1, identified in 2001 in Acinetobacter sp. EB104, was the first bacterial P450 specifically associated with this activity [12], but since then other members of the CYP153 family in diverse bacteria have been shown to catalyze the ω-hydroxylation of medium-length linear hydrocarbons [13], [14]. The ω-hydroxylation of hydrocarbons in bacteria enables them to grow on these compounds as their sole
CYP4 chain length tolerance
The relationship between fatty acid chain length and the hydroxylation regiospecificity of CYP4 enzymes has been extensively examined. The results of a typical study of rat CYP4A1, CYP4A2, CYP4A3, and CYP4A8, as well as human CYP4A11, shows that ω-regioselectivity tends to decrease for substrates longer than lauric acid (Table 2) [51]. A similar finding is obtained with rabbit CYP4A7, for which the fatty acid hydroxylation specificity gradually decreases from an ω/(ω−1)-ratio of 15.1 for lauric
Crystal structure of CYP124A1
The position in the M. tuberculosis genome of the gene coding for CYP124A1 adjacent to the gene for an enzyme that sulfates a terminal hydroxyl on a saturated isoprenoid chain led to the discovery that it catalyzes the ω-hydroxylation of branched hydrocarbon acids [39]. It has much lower activity for the oxidation of linear fatty acids and no detectable activity for the oxidation of branched or unbranched hydrocarbons (Table 3) [39]. Furthermore, the low activity for unbranched fatty acid
Conclusions
To achieve preferential ω-hydroxylation of hydrocarbon chains, cytochrome P450 enzymes must physically constrain their substrates so that the more facile (ω−1)-hydroxylations become disfavored. Analysis of all the ω-hydroxylation data indicates that this is achieved by steric interactions between the substrate and the protein residues rather than by an alteration of the reactivity of the ferryl species. The two crystal structures now available of M. tuberculosis enzymes that catalyze the
Acknowledgment
The preparation of this review and the experimental work at UCSF was supported by grants GM25515 and AI74824.
References (70)
- et al.
Arch. Biochem. Biophys.
(2010) - et al.
J. Biol. Chem.
(1988) - et al.
J. Lipid Res.
(1999) - et al.
Biochim. Biophys. Acta
(1975) - et al.
Biochem. Biophys. Res. Commun.
(2001) - et al.
Enzyme Microb. Technol.
(2007) - et al.
Fungal Genet. Biol.
(1998) - et al.
J. Biol. Chem.
(1998) - et al.
Biochem. Biophys. Res. Commun.
(1998) Biochem. Pharmacol.
(2008)
Arch. Biochem. Biophys.
Arch. Biochem. Biophys.
Biochem. Biophys. Res. Commun.
J. Biol. Chem.
Biochem. Biophys. Res. Commun.
Plant Sci.
Biochem. Biophys. Res. Commun.
Arch. Biochem. Biophys.
FEBS Lett.
J. Lipid Res.
Arch. Biochem. Biophys.
J. Lipid Res.
Cell
J. Biol. Chem.
J. Biol. Chem.
Arch. Biochem. Biophys.
Arch. Biochem. Biophys.
J. Biol. Chem.
Chem. Biol. Interact.
Biochem. Biophys. Res. Commun.
Biochim. Biophys. Acta
Biochem. Biophys. Res. Commun.
J. Biol. Chem.
J. Biol. Chem.
J. Biol. Chem.
Cited by (56)
The oxidation of cholesterol derivatives by the CYP124 and CYP142 enzymes from Mycobacterium marinum
2023, Journal of Steroid Biochemistry and Molecular BiologyAccumulation and metabolism of pyroxasulfone in tomato seedlings
2023, Ecotoxicology and Environmental SafetyThe catalytic activity and structure of the lipid metabolizing CYP124 cytochrome P450 enzyme from Mycobacterium marinum
2023, Archives of Biochemistry and BiophysicsSynthesis and interaction of terminal unsaturated chemical probes with Mycobacterium tuberculosis CYP124A1
2021, Bioorganic and Medicinal ChemistryCitation Excerpt :Crystal and co-crystal structures were solved for the holo-enzyme as well as the phytanic acid-bound form.38 The co-crystal structure suggests a model by which the CYP124A1 active site enforces unfavorable regioselectivity,38,40 whereby a small cleft situated near the heme iron binds one of the methyl groups of the methyl-branched substrates, which positions the other methyl group near the heme iron where it can undergo oxidation. For linear lipids, the terminal end is thought to alternate between being bound in the methyl-binding pocket and being positioned near the heme iron.
A cytochrome P450 from the mustard leaf beetles hydroxylates geraniol, a key step in iridoid biosynthesis
2019, Insect Biochemistry and Molecular Biology