Abstract
We have examined the interaction of the trp repressor from Escherichia coli with a 20 base-pair synthetic operator. Nonspecific binding was relatively strong (Kd=2 μM), but only weakly sensitive to the concentration of added salt ( (d log Kd) (d log [Na])= -1). 1H-NMR studies indicate that the structure of the repressor is not greatly altered on forming the complex, and that few if any of the lysine and arginine residues make direct contact with the DNA. However, the mobility of one of the two tyrosine residues is significantly decreased in the complex. The repressor makes close contact with the major grooves of the operator such that the base protons are broadened much more than expected on the basis of increased correlation time. There are large, differential changes in chemical shifts of the imino protons on forming the complex, as well as changes in the rate constants for exchange. The fraying of the ends is greatly diminished, consistent with a target size of about 20 base-pairs. The effects of the repressor on the NMR spectra and relaxation rate constants can be interpreted as a change in the conformation of the operator, possibly a kinking in the centre of the molecule.
Original language | English |
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Pages (from-to) | 58-70 |
Number of pages | 13 |
Journal | Biochimica et Biophysica Acta - Gene Structure and Expression |
Volume | 909 |
Issue number | 1 |
DOIs | |
State | Published - Jun 6 1987 |
Bibliographical note
Funding Information:This work was supported by NIGMS Grant No. GM 33385. J.F.L. gratefully acknowledges NATO and the Phillipe Foundation for grants. We thank Drs. R.W. King and A. Aulabaugh for reading the manuscripta nd their comments.
Funding
This work was supported by NIGMS Grant No. GM 33385. J.F.L. gratefully acknowledges NATO and the Phillipe Foundation for grants. We thank Drs. R.W. King and A. Aulabaugh for reading the manuscripta nd their comments.
Funders | Funder number |
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Phillipe Foundation | |
National Institute of General Medical Sciences | R01GM033385 |
North Atlantic Treaty Organization |
Keywords
- Imino proton exchange
- NMR
- Protein-DNA interaction
- Repressor-operator interaction
- Tryptophan operator
ASJC Scopus subject areas
- Structural Biology
- Biophysics
- Biochemistry
- Genetics