TY - JOUR
T1 - Role of hydration in the binding of lac repressor to DNA
AU - Fried, Michael G.
AU - Stickle, Douglas F.
AU - Smirnakis, Karen Vossen
AU - Adams, Claire
AU - MacDonald, Douglas
AU - Lu, Ponzy
PY - 2002/12/27
Y1 - 2002/12/27
N2 - The osmotic stress technique was used to measure changes in macromolecular hydration that accompany binding of wild-type Escherichia coli lactose (lac) repressor to its regulatory site (operator O1) in the lac promoter and its transfer from site O1 to nonspecific DNA. Binding at O1 is accompanied by the net release of 260 ± 32 water molecules. If all are released from macromolecular surfaces, this result is consistent with a net reduction of solvent-accessible surface area of 2370 ± 550 Å2. This area is only slightly smaller than the macromolecular interface calculated for a crystalline repressor dimer-O1 complex but is significantly smaller than that for the corresponding complex with the symmetrical optimized Osym operator. The transfer of repressor from site O1 to nonspecific DNA is accompanied by the net uptake of 93 ± 10 water molecules. Together these results imply that formation of a nonspecific complex is accompanied by the net release of 165 ± 43 water molecules. The enhanced stabilities of repressor-DNA complexes with increasing osmolality may contribute to the ability of Escherichia coli cells to tolerate dehydration and/or high external salt concentrations.
AB - The osmotic stress technique was used to measure changes in macromolecular hydration that accompany binding of wild-type Escherichia coli lactose (lac) repressor to its regulatory site (operator O1) in the lac promoter and its transfer from site O1 to nonspecific DNA. Binding at O1 is accompanied by the net release of 260 ± 32 water molecules. If all are released from macromolecular surfaces, this result is consistent with a net reduction of solvent-accessible surface area of 2370 ± 550 Å2. This area is only slightly smaller than the macromolecular interface calculated for a crystalline repressor dimer-O1 complex but is significantly smaller than that for the corresponding complex with the symmetrical optimized Osym operator. The transfer of repressor from site O1 to nonspecific DNA is accompanied by the net uptake of 93 ± 10 water molecules. Together these results imply that formation of a nonspecific complex is accompanied by the net release of 165 ± 43 water molecules. The enhanced stabilities of repressor-DNA complexes with increasing osmolality may contribute to the ability of Escherichia coli cells to tolerate dehydration and/or high external salt concentrations.
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U2 - 10.1074/jbc.M208540200
DO - 10.1074/jbc.M208540200
M3 - Article
C2 - 12379649
AN - SCOPUS:0347367039
SN - 0021-9258
VL - 277
SP - 50676
EP - 50682
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 52
ER -