Linked Life Data

11878987

Source:http://linkedlifedata.com/resource/pubmed/id/11878987

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
10
pubmed:dateCreated
2002-3-6
pubmed:abstractText
FosA is a manganese metalloglutathione transferase that confers resistance to the broad-spectrum antibiotic fosfomycin, (1R,2S)-epoxypropylphosphonic acid. The reaction catalyzed by FosA involves the attack by glutathione on fosfomycin to yield the product 1-(S-glutathionyl)-2-hydroxypropylphosphonic acid. The enzyme is a dimer of 16 kDa subunits, each of which harbors one mononuclear Mn(II) site. The coordination environment of the Mn(II) in the FosA x Mn(2+) complex is composed of a glutamate and two histidine ligands and three water molecules. Here we report EPR spectroscopic studies on FosA, in which EPR spectra were obtained at 35 GHz and 2 K using dispersion-detection rapid-passage techniques. This approach provides an absorption envelope line shape, in contrast to the conventional (slow-passage) derivative line shape, and is a more reliable way to collect spectra from Mn(II) centers with large zero-field splitting. We obtain excellent spectra of FosA bound with substrate, substrate analogue phosphate ion, and product, whereas these states cannot be studied by X-band, slow-passage methods. Simulation of the EPR spectra shows that binding of substrate or analogue causes a profound change in the electronic parameters of the Mn(II) ion. The axial zero-field splitting changes from [D] = 0.06 cm(-1) for substrate-free enzyme to 0.23 cm(-1) for fosfomycin-bound enzyme, 0.28 (1) cm(-1) for FosA with phosphate, and 0.27 (1) cm(-1) with product. Such a large zero-field splitting is uncommon for Mn(II). A simple ligand field analysis of this change indicates that binding of the phosphonate/phosphate group of substrate or analogue changes the electronic energy levels of the Mn(II) 3d orbitals by several thousand cm(-1), indicative of a significant change in the Mn(II) coordination sphere. Comparison with related enzymes (glyoxalase I and MnSOD) suggests that the change in the coordination environment on substrate binding may correspond to loss of the glutamate ligand.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Mar
pubmed:issn
0002-7863
pubmed:author
pubmed:issnType
Print
pubmed:day
13
pubmed:volume
124
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
2318-26
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
2002
pubmed:articleTitle
EPR study of substrate binding to the Mn(II) active site of the bacterial antibiotic resistance enzyme FosA: a better way to examine Mn(II).
pubmed:affiliation
Department of Chemistry, Northwestern University, Evanston, Illinois 60208-3113, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, U.S. Gov't, Non-P.H.S.