Binding of MetJ repressor to specific and nonspecific DNA and effect of S-adenosylmethionine on these interactions.
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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.
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Published Version (Please cite this version)10.1021/bi902011f
Publication InfoAugustus, 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.
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University Distinguished Service Professor of Radiology
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