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Crystal structures of cobalamin-independent methionine synthase (MetE) from Streptococcus mutans: a dynamic zinc-inversion model.
- Source :
-
Journal of molecular biology [J Mol Biol] 2011 Sep 30; Vol. 412 (4), pp. 688-97. Date of Electronic Publication: 2011 Aug 05. - Publication Year :
- 2011
-
Abstract
- Cobalamin-independent methionine synthase (MetE) catalyzes the direct transfer of a methyl group from methyltetrahydrofolate to l-homocysteine to form methionine. Previous studies have shown that the MetE active site coordinates a zinc atom, which is thought to act as a Lewis acid and plays a role in the activation of thiol. Extended X-ray absorption fine structure studies and mutagenesis experiments identified the zinc-binding site in MetE from Escherichia coli. Further structural investigations of MetE from Thermotoga maritima lead to the proposition of two models: "induced fit" and "dynamic equilibrium", to account for the catalytic mechanisms of MetE. Here, we present crystal structures of oxidized and zinc-replete MetE from Streptococcus mutans at the physiological pH. The structures reveal that zinc is mobile in the active center and has the possibility to invert even in the absence of homocysteine. These structures provide evidence for the dynamic equilibrium model.<br /> (Copyright © 2011 Elsevier Ltd. All rights reserved.)
- Subjects :
- Binding Sites
Crystallography, X-Ray
Escherichia coli enzymology
Escherichia coli metabolism
Kinetics
Methionine biosynthesis
Methionine chemistry
Methyltransferases metabolism
Models, Chemical
Models, Molecular
Protein Structure, Tertiary
Streptococcus mutans chemistry
Streptococcus mutans metabolism
Thermotoga maritima enzymology
Thermotoga maritima metabolism
Zinc chemistry
Methyltransferases chemistry
Streptococcus mutans enzymology
Zinc metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 1089-8638
- Volume :
- 412
- Issue :
- 4
- Database :
- MEDLINE
- Journal :
- Journal of molecular biology
- Publication Type :
- Academic Journal
- Accession number :
- 21840320
- Full Text :
- https://doi.org/10.1016/j.jmb.2011.08.005