7TZM

The crystal structure of WT CYP199A4 bound to 4-iodobenzoic acid

Summary for 7TZM

• Entry DOI: 10.2210/pdb7tzm/pdb
• Descriptor: Cytochrome P450, 4-iodobenzoic acid, PROTOPORPHYRIN IX CONTAINING FE, ... (5 entities in total)
• Functional Keywords: cytochrome p450, 4-iodobenzoic acid, oxidoreductase
• Biological source: Rhodopseudomonas palustris
• Total number of polymer chains: 1
• Total formula weight: 45487.39

Authors

Podgorski, M.N.,Bell, S.G. (deposition date: 2022-02-16, release date: 2023-03-15, Last modification date: 2023-10-25)

Primary citation

Coleman, T.,Podgorski, M.N.,Doyle, M.L.,Scaffidi-Muta, J.M.,Campbell, E.C.,Bruning, J.B.,De Voss, J.J.,Bell, S.G.
Cytochrome P450-catalyzed oxidation of halogen-containing substrates.
J.Inorg.Biochem., 244:112234-112234, 2023

PubMed Abstract: Cytochrome P450 (CYP) enzymes are heme-thiolate monooxygenases which catalyze the oxidation of aliphatic and aromatic C-H bonds and other reactions. The oxidation of halogens by cytochrome P450 enzymes has also been reported. Here we use CYP199A4, from the bacterium Rhodopseudomonas palustris strain HaA2, with a range of para-substituted benzoic acid ligands, which contain halogens, to assess if this enzyme can oxidize these species or if the presence of these electronegative atoms can alter the outcome of P450-catalyzed reactions. Despite binding to the enzyme, there was no detectable oxidation of any of the 4-halobenzoic acids. CYP199A4 was, however, able to efficiently catalyze the oxidation of both 4-chloromethyl- and 4-bromomethyl-benzoic acid to 4-formylbenzoic acid via hydroxylation of the α‑carbon. The 4-chloromethyl substrate bound in the enzyme active site in a similar manner to 4-ethylbenzoic acid. This places the benzylic α‑carbon hydrogens in an unfavorable position for abstraction indicating a degree of substrate mobility must be possible within the active site. CYP199A4 catalyzed oxidations of 4-(2'-haloethyl)benzoic acids yielding α-hydroxylation and desaturation metabolites. The α-hydroxylation product was the major metabolite. The desaturation pathway is significantly disfavored compared to 4-ethylbenzoic acid. This may be due to the electron-withdrawing halogen atom or a different positioning of the substrate within the active site. The latter was demonstrated by the X-ray crystal structures of CYP199A4 with these substrates. Overall, the presence of a halogen atom positioned close to the heme iron can alter the binding orientation and outcomes of enzyme-catalyzed oxidation.

PubMed: 37116269
DOI: 10.1016/j.jinorgbio.2023.112234

Experimental method

X-RAY DIFFRACTION (1.524 Å)