Linked Life Data

7727419

Source:http://linkedlifedata.com/resource/pubmed/id/7727419

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
16
pubmed:dateCreated
1995-6-1
pubmed:abstractText
The MutT enzyme catalyzes the hydrolysis of nucleoside triphosphates to nucleoside monophosphates and pyrophosphate by substitution at the rarely attacked beta-phosphorus. Nucleotides containing bulky substituents at the 8 position of the purine ring are preferentially hydrolyzed. The conformation of the MutT-bound nonhydrolyzable substrate analog Mg(2+)-AMPCPP, determined by 10 intramolecular NOEs and molecular dynamics refinement using a full relaxation matrix analysis with back-calculation of the NOESY intensities, is high anti (chi = 53 +/- 9 degrees), with a C2'-exo, O1'-endo sugar pucker. Similarly, the product of dGTP hydrolysis, dGMP, also binds MutT in a high anti (chi = 73 +/- 9 degrees) C1'-endo conformation based on seven intramolecular NOEs. Such high anti rotations of the base would allow MutT to accommodate nucleotides substituted at the C-8 position with no intramolecular clashes. Changes in chemical shifts in the 1H-15N spectra of the enzyme induced by Mg2+ and Mg2+ AMPCPP suggest that the metal activator and nucleotide interact with residues in loop I, at the carboxyl end of helix I, loop II, loop III, and beta-strands A and B of the secondary structure of MutT. The displacement of Mg2+ by Mn2+ causes the selective disappearance due to paramagnetic broadening of 1H-15N cross peaks from G37, G38, and K39 in loop I and E57 in helix I. Eleven intermolecular NOEs between Mg2+AMPCPP and hydrophobic residues of MutT are found, three of which are tentatively assigned to L67 in loop II and three to L54 in helix I. Similarly, seven intermolecular NOEs between dGMP and hydrophobic residues of the enzyme are found, four of which are tentatively assigned to L54 and two to V58, both in helix I. These interactions indicate that the loop I-helix I-loop II motif contributes significantly to the active site of MutT in accord with mutagenesis studies and with sequence homologies among MutT-like NTP pyrophosphohydrolases.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Apr
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
25
pubmed:volume
34
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
5577-86
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed-meshheading:7727419-Adenosine Triphosphate, pubmed-meshheading:7727419-Amino Acid Sequence, pubmed-meshheading:7727419-Bacterial Proteins, pubmed-meshheading:7727419-Binding Sites, pubmed-meshheading:7727419-Escherichia coli, pubmed-meshheading:7727419-Escherichia coli Proteins, pubmed-meshheading:7727419-Guanosine Triphosphate, pubmed-meshheading:7727419-Magnetic Resonance Spectroscopy, pubmed-meshheading:7727419-Models, Molecular, pubmed-meshheading:7727419-Models, Structural, pubmed-meshheading:7727419-Molecular Conformation, pubmed-meshheading:7727419-Molecular Sequence Data, pubmed-meshheading:7727419-Phosphoric Monoester Hydrolases, pubmed-meshheading:7727419-Protein Conformation, pubmed-meshheading:7727419-Protein Structure, Secondary, pubmed-meshheading:7727419-Pyrophosphatases, pubmed-meshheading:7727419-Sequence Homology, Amino Acid
pubmed:year
1995
pubmed:articleTitle
NMR studies of the conformations and location of nucleotides bound to the Escherichia coli MutT enzyme.
pubmed:affiliation
Department of Biology, Johns Hopkins University, Baltimore, Maryland 21218, USA.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, U.S. Gov't, P.H.S.