The first crystallographic structures of a catechol 1,2-dioxygenase from a Gram-positive bacterium Rhodococcus opacus 1CP (Rho 1,2-CTD), a Fe(III) ion containing enzyme specialized in the aerobic biodegradation of catechols, and its adducts with catechol, 3-methylcatechol, 4-methylcatechol, pyrogallol (benzene-1,2,3-triol), 3-chlorocatechol, 4-chlorocatechol, 3,5-dichlorocatechol, 4,5-dichlorocatechol and protocatechuate (3,4-dihydroxybenzoate) have been determined and analyzed. This study represents the first extensive characterization of catechols adducts of 1,2-CTDs. The structural analyses reveal the diverse modes of binding to the active metal iron ion of the tested catechols thus allowing to identify the residues selectively involved in recognition of the diverse substrates by this class of enzymes. The comparison is further extended to the structural and functional characteristics of the other 1,2-CTDs isolated from Gram-positive and Gram-negative bacteria. Moreover the high structural homology of the present enzyme with the 3-chlorocatechol 1,2-dioxygenase from the same bacterium are discussed in terms of their different substrate specificity. The catalytic rates for Rho 1,2-CTD conversion of the tested compounds are also compared with the cal- culated energies of the highest occupied molecular orbital (EHOMO) of the substrates. A quantitative relationship (R = 0.966) between the ln kcat and the calculated electronic parameter EHOMO was obtained for catechol, 3-methylcatechol, 4-methylcatechol, pyrogallol, 3-chlorocatechol, 4-chlorocatechol. This indicates that for these substrates the rate-limiting step of the reaction cycle is dependent on their nucleophilic reactivity. The discrepancies observed in the quantitative relationship for 3,5-dichlorocatechol, 4,5-dichlorocatechol and protocatechuate are ascribed to the sterical hindrances leading to the distorted binding of such catechols observed in the corresponding structures.

Catechol 1,2-dioxygenase from the Gram-positive Rhodococcus opacus 1CP: Quantitative structure/activity relationship and the crystal structures of native enzyme and catechols adducts / I. Matera; M. Ferraroni; M. Kolomytseva; L. Golovleva; A. Scozzafava; F. Briganti. - In: JOURNAL OF STRUCTURAL BIOLOGY. - ISSN 1047-8477. - STAMPA. - 170:(2010), pp. 548-564.

Catechol 1,2-dioxygenase from the Gram-positive Rhodococcus opacus 1CP: Quantitative structure/activity relationship and the crystal structures of native enzyme and catechols adducts

FERRARONI, MARTA;SCOZZAFAVA, ANDREA;BRIGANTI, FABRIZIO
2010

Abstract

The first crystallographic structures of a catechol 1,2-dioxygenase from a Gram-positive bacterium Rhodococcus opacus 1CP (Rho 1,2-CTD), a Fe(III) ion containing enzyme specialized in the aerobic biodegradation of catechols, and its adducts with catechol, 3-methylcatechol, 4-methylcatechol, pyrogallol (benzene-1,2,3-triol), 3-chlorocatechol, 4-chlorocatechol, 3,5-dichlorocatechol, 4,5-dichlorocatechol and protocatechuate (3,4-dihydroxybenzoate) have been determined and analyzed. This study represents the first extensive characterization of catechols adducts of 1,2-CTDs. The structural analyses reveal the diverse modes of binding to the active metal iron ion of the tested catechols thus allowing to identify the residues selectively involved in recognition of the diverse substrates by this class of enzymes. The comparison is further extended to the structural and functional characteristics of the other 1,2-CTDs isolated from Gram-positive and Gram-negative bacteria. Moreover the high structural homology of the present enzyme with the 3-chlorocatechol 1,2-dioxygenase from the same bacterium are discussed in terms of their different substrate specificity. The catalytic rates for Rho 1,2-CTD conversion of the tested compounds are also compared with the cal- culated energies of the highest occupied molecular orbital (EHOMO) of the substrates. A quantitative relationship (R = 0.966) between the ln kcat and the calculated electronic parameter EHOMO was obtained for catechol, 3-methylcatechol, 4-methylcatechol, pyrogallol, 3-chlorocatechol, 4-chlorocatechol. This indicates that for these substrates the rate-limiting step of the reaction cycle is dependent on their nucleophilic reactivity. The discrepancies observed in the quantitative relationship for 3,5-dichlorocatechol, 4,5-dichlorocatechol and protocatechuate are ascribed to the sterical hindrances leading to the distorted binding of such catechols observed in the corresponding structures.
2010
170
548
564
I. Matera; M. Ferraroni; M. Kolomytseva; L. Golovleva; A. Scozzafava; F. Briganti
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Utilizza questo identificatore per citare o creare un link a questa risorsa: https://hdl.handle.net/2158/385519
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