6BZ5

Structure and mechanism of salicylate hydroxylase from Pseudomonas putida G7

Summary for 6BZ5

• Entry DOI: 10.2210/pdb6bz5/pdb
• Descriptor: Salicylate hydroxylase, IODIDE ION, GLYCEROL, ... (6 entities in total)
• Functional Keywords: aromatic hydrocarbons catabolism, salicylate hydroxylase, flavoprotein, oxidoreductase
• Biological source: Pseudomonas putida (Arthrobacter siderocapsulatus)
• Total number of polymer chains: 2
• Total formula weight: 101360.44

Authors

Nagem, R.A.P.,Costa, D.M.A. (deposition date: 2017-12-22, release date: 2018-12-26, Last modification date: 2024-03-13)

Primary citation

Costa, D.M.A.,Gomez, S.V.,de Araujo, S.S.,Pereira, M.S.,Alves, R.B.,Favaro, D.C.,Hengge, A.C.,Nagem, R.A.P.,Brandao, T.A.S.
Catalytic mechanism for the conversion of salicylate into catechol by the flavin-dependent monooxygenase salicylate hydroxylase.
Int.J.Biol.Macromol., 129:588-600, 2019

PubMed Abstract: Salicylate hydroxylase (NahG) is a flavin-dependent monooxygenase that catalyzes the decarboxylative hydroxylation of salicylate into catechol in the naphthalene degradation pathway in Pseudomonas putida G7. We explored the mechanism of action of this enzyme in detail using a combination of structural and biophysical methods. NahG shares many structural and mechanistic features with other versatile flavin-dependent monooxygenases, with potential biocatalytic applications. The crystal structure at 2.0 Å resolution for the apo form of NahG adds a new snapshot preceding the FAD binding in flavin-dependent monooxygenases. The k/K for the salicylate reaction catalyzed by the holo form is >10 M s at pH 8.5 and 25 °C. Hammett plots for K and k using substituted salicylates indicate change in rate-limiting step. Electron-donating groups favor the hydroxylation of salicylate by a peroxyflavin to yield a Wheland-like intermediate, whereas the decarboxylation of this intermediate is faster for electron-withdrawing groups. The mechanism is supported by structural data and kinetic studies at different pHs. The salicylate carboxyl group lies near a hydrophobic region that aids decarboxylation. A conserved histidine residue is proposed to assist the reaction by general base/general acid catalysis.

PubMed: 30703421
DOI: 10.1016/j.ijbiomac.2019.01.135

Experimental method

X-RAY DIFFRACTION (2.006 Å)