Effects of molecular crowding on the interaction between DNA and the Escherichia coli regulatory protein TyrR.
Fluorescence quenching has been used to measure quantitatively the effects of sucrose and triethylene glycol on the interaction between the Escherichia coli regulatory protein TyrR and a 30-basepair oligonucleotide containing the strong TyrR box of the TyrR operon. It was observed that the apparent binding constant increased in the presence of co-solutes, the dependence of the logarithm of the apparent binding constant on molar concentration being indistinguishable and essentially linear for both co-solutes. This activation of the TyrR-oligonucleotide interaction is attributed to thermodynamic nonideality arising from molecular crowding, an interpretation which is supported by the reasonable agreement observed between the experimental extent of reaction enhancement and that predicted on the statistical-mechanical basis of excluded volume.
Poon
J
J
Russell Grimwade School of Biochemistry and Molecular Biology, University of Melbourne, Parkville, Victoria, Australia.
Bailey
M
M
Winzor
D J
DJ
Davidson
B E
BE
Sawyer
W H
WH
D001483:Base Sequence; D055592:Biophysical Phenomena; D001703:Biophysics; D004269:DNA, Bacterial / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins; D007700:Kinetics; D046911:Macromolecular Substances; D009876:Operon; D009997:Osmotic Pressure; D011485:Protein Binding; D012097:Repressor Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D013050:Spectrometry, Fluorescence; D013816:Thermodynamics
D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D046911:Macromolecular Substances; D012097:Repressor Proteins; C069256:TyrR protein, E coli