Linked Life Data

14622009

Source:http://linkedlifedata.com/resource/pubmed/id/14622009

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
46
pubmed:dateCreated
2003-11-18
pubmed:abstractText
The Rieske dioxygenase, anthranilate 1,2-dioxygenase, catalyzes the 1,2-dihydroxylation of anthranilate (2-aminobenzoate). As in all characterized Rieske dioxygenases, the catalytic conversion to the diol occurs within the dioxygenase component, AntAB, at a mononuclear iron site which accepts electrons from a proximal Rieske [2Fe-2S] center. In the related naphthalene dioxygenase (NDO), a conserved aspartate residue lies between the mononuclear and Rieske iron centers, and is hydrogen-bonded to a histidine ligand of the Rieske center. Engineered substitutions of this aspartate residue led to complete inactivation, which was proposed to arise from elimination of a productive intersite electron transfer pathway [Parales, R. E., Parales, J. V., and Gibson, D. T. (1999) J. Bacteriol. 181, 1831-1837]. Substitutions of the corresponding aspartate, D218, in AntAB with alanine, asparagine, or glutamate also resulted in enzymes that were completely inactive over a wide pH range despite retention of the hexameric quaternary structure and iron center occupancy. The Rieske center reduction potential of this variant was measured to be approximately 100 mV more negative than that for the wild-type enzyme at neutral pH. The wild-type AntAB became completely inactive at pH 9 and exhibited an altered Rieske center absorption spectrum which resembled that of the D218 variants at neutral pH. These results support a role for this aspartate in maintaining the protonated state and reduction potential of the Rieske center. Both the wild-type and D218A variant AntABs exhibited substrate-dependent rapid phases of Rieske center oxidations in stopped-flow time courses. This observation does not support a role for this aspartate in a facile intersite electron transfer pathway or in productive substrate gating of the Rieske center reduction potential. However, since the single turnovers resulted in anthranilate dihydroxylation by the wild-type enzyme but not by the D218A variant, this aspartate must also play a crucial role in substrate dihydroxylation at or near the mononuclear iron site.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Nov
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
25
pubmed:volume
42
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
13625-36
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed-meshheading:14622009-Acinetobacter, pubmed-meshheading:14622009-Amino Acid Substitution, pubmed-meshheading:14622009-Aspartic Acid, pubmed-meshheading:14622009-Bacterial Proteins, pubmed-meshheading:14622009-Dithionite, pubmed-meshheading:14622009-Electron Spin Resonance Spectroscopy, pubmed-meshheading:14622009-Histidine, pubmed-meshheading:14622009-Hydrogen-Ion Concentration, pubmed-meshheading:14622009-Iron-Sulfur Proteins, pubmed-meshheading:14622009-Ligands, pubmed-meshheading:14622009-Mixed Function Oxygenases, pubmed-meshheading:14622009-Models, Molecular, pubmed-meshheading:14622009-NADP, pubmed-meshheading:14622009-Oxidation-Reduction, pubmed-meshheading:14622009-Protons, pubmed-meshheading:14622009-Recombinant Proteins, pubmed-meshheading:14622009-Spectrophotometry, Ultraviolet
pubmed:year
2003
pubmed:articleTitle
Histidine ligand protonation and redox potential in the rieske dioxygenases: role of a conserved aspartate in anthranilate 1,2-dioxygenase.
pubmed:affiliation
Department of Chemistry, Center for Metalloenzyme Studies, University of Georgia, Athens, Georgia 30602, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.