Binding of MetJ repressor to specific and nonspecific DNA and effect of S-adenosylmethionine on these interactions.
Abstract
We have used analytical ultracentrifugation to characterize the binding of the methionine
repressor protein, MetJ, to synthetic oligonucleotides containing zero to five specific
recognition sites, called metboxes. For all lengths of DNA studied, MetJ binds more
tightly to repeats of the consensus sequence than to naturally occurring metboxes,
which exhibit a variable number of deviations from the consensus. Strong cooperative
binding occurs only in the presence of two or more tandem metboxes, which facilitate
protein-protein contacts between adjacent MetJ dimers, but weak affinity is detected
even with DNA containing zero or one metbox. The affinity of MetJ for all of the DNA
sequences studied is enhanced by the addition of SAM, the known cofactor for MetJ
in the cell. This effect extends to oligos containing zero or one metbox, both of
which bind two MetJ dimers. In the presence of a large excess concentration of metbox
DNA, the effect of cooperativity is to favor populations of DNA oligos bound by two
or more MetJ dimers rather than a stochastic redistribution of the repressor onto
all available metboxes. These results illustrate the dynamic range of binding affinity
and repressor assembly that MetJ can exhibit with DNA and the effect of the corepressor
SAM on binding to both specific and nonspecific DNA.
Type
Journal articleSubject
Bacterial ProteinsBase Sequence
Consensus Sequence
DNA
Dimerization
Fractionation, Field Flow
Kinetics
Methionine
Molecular Weight
Oligodeoxyribonucleotides
Protein Binding
Repressor Proteins
S-Adenosylmethionine
Ultracentrifugation
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https://hdl.handle.net/10161/4018Published Version (Please cite this version)
10.1021/bi902011fPublication Info
Augustus, Anne M; Sage, Harvey; & Spicer, Leonard D (2010). Binding of MetJ repressor to specific and nonspecific DNA and effect of S-adenosylmethionine
on these interactions. Biochemistry, 49(15). pp. 3289-3295. 10.1021/bi902011f. Retrieved from https://hdl.handle.net/10161/4018.This is constructed from limited available data and may be imprecise. To cite this
article, please review & use the official citation provided by the journal.
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Show full item recordScholars@Duke
Leonard D. Spicer
University Distinguished Service Professor Emeritus
The focus of this laboratory is the study of structure/function relationships in
biological macromolecules and their binding interactions. The principal method we
use for system characterization is magnetic resonance spectroscopy. One specific
area of interest is the structural characterization of functional domains in proteins
which regulate the transcription of DNA coding for biosynthetic enzymes. The system
under current investigation is the methionine repressor protein metJ, its cor

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