Dataset Information

Structure and increased thermostability of Rhodococcus sp. naphthalene 1,2-dioxygenase.

ABSTRACT: Rieske nonheme iron oxygenases form a large class of aromatic ring-hydroxylating dioxygenases found in microorganisms. These enzymes enable microorganisms to tolerate and even exclusively utilize aromatic compounds for growth, making them good candidates for use in synthesis of chiral intermediates and bioremediation. Studies of the chemical stability and thermostability of these enzymes thus become important. We report here the structure of free and substrate (indole)-bound forms of naphthalene dioxygenase from Rhodococcus sp. strain NCIMB12038. The structure of the Rhodococcus enzyme reveals that, despite a approximately 30% sequence identity between these naphthalene dioxygenases, their overall structures superpose very well with a root mean square deviation of less than 1.6 A. The differences in the active site of the two enzymes are pronounced near the entrance; however, indole binds to the Rhodococcus enzyme in the same orientation as in the Pseudomonas enzyme. Circular dichroism spectroscopy experiments show that the Rhodococcus enzyme has higher thermostability than the naphthalene dioxygenase from Pseudomonas species. The Pseudomonas enzyme has an apparent melting temperature of 55 degrees C while the Rhodococcus enzyme does not completely unfold even at 95 degrees C. Both enzymes, however, show similar unfolding behavior in urea, and the Rhodococcus enzyme is only slightly more tolerant to unfolding by guanidine hydrochloride. Structure analysis suggests that the higher thermostability of the Rhodococcus enzyme may be attributed to a larger buried surface area and extra salt bridge networks between the alpha and beta subunits in the Rhodococcus enzyme.

SUBMITTER: Gakhar L

PROVIDER: S-EPMC1272967 | biostudies-literature | 2005 Nov

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Structure and increased thermostability of Rhodococcus sp. naphthalene 1,2-dioxygenase.

Gakhar Lokesh L Malik Zulfiqar A ZA Allen Christopher C R CC Lipscomb David A DA Larkin Michael J MJ Ramaswamy S S

Journal of bacteriology 20051101 21

Rieske nonheme iron oxygenases form a large class of aromatic ring-hydroxylating dioxygenases found in microorganisms. These enzymes enable microorganisms to tolerate and even exclusively utilize aromatic compounds for growth, making them good candidates for use in synthesis of chiral intermediates and bioremediation. Studies of the chemical stability and thermostability of these enzymes thus become important. We report here the structure of free and substrate (indole)-bound forms of naphthalene ...[more]

PMID: 16237006

Similar Datasets

Project description:The two-component anthranilate 1,2-dioxygenase of the bacterium Acinetobacter sp. strain ADP1 was expressed in Escherichia coli and purified to homogeneity. This enzyme converts anthranilate (2-aminobenzoate) to catechol with insertion of both atoms of O(2) and consumption of one NADH. The terminal oxygenase component formed an alpha(3)beta(3) hexamer of 54- and 19-kDa subunits. Biochemical analyses demonstrated one Rieske-type [2Fe-2S] center and one mononuclear nonheme iron center in each large oxygenase subunit. The reductase component, which transfers electrons from NADH to the oxygenase component, was found to contain approximately one flavin adenine dinucleotide and one ferredoxin-type [2Fe-2S] center per 39-kDa monomer. Activities of the combined components were measured as rates and quantities of NADH oxidation, substrate disappearance, product appearance, and O(2) consumption. Anthranilate conversion to catechol was stoichiometrically coupled to NADH oxidation and O(2) consumption. The substrate analog benzoate was converted to a nonaromatic benzoate 1,2-diol with similarly tight coupling. This latter activity is identical to that of the related benzoate 1, 2-dioxygenase. A variant anthranilate 1,2-dioxygenase, previously found to convey temperature sensitivity in vivo because of a methionine-to-lysine change in the large oxygenase subunit, was purified and characterized. The purified M43K variant, however, did not hydroxylate anthranilate or benzoate at either the permissive (23 degrees C) or nonpermissive (39 degrees C) growth temperatures. The wild-type anthranilate 1,2-dioxygenase did not efficiently hydroxylate methylated or halogenated benzoates, despite its sequence similarity to broad-substrate specific dioxygenases that do. Phylogenetic trees of the alpha and beta subunits of these terminal dioxygenases that act on natural and xenobiotic substrates indicated that the subunits of each terminal oxygenase evolved from a common ancestral two-subunit component.

Dataset Information

Structure and increased thermostability of Rhodococcus sp. naphthalene 1,2-dioxygenase.

Publications

Structure and increased thermostability of Rhodococcus sp. naphthalene 1,2-dioxygenase.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets