Yh. Cui et al., THE LEUCINE-RESPONSIVE REGULATORY PROTEIN (LRP) FROM ESCHERICHIA-COLI- STOICHIOMETRY AND MINIMAL REQUIREMENTS FOR BINDING TO DNA, The Journal of biological chemistry, 271(12), 1996, pp. 6611-6617
Lrp (Leucine-responsive regulatory protein) regulates the expression o
f a number of operons in Escherichia coli, A recent study of DNA seque
nces recognized by Lrp established the consensus as a 15-bp sequence,
YAGHA-WATTWTDCTR (Y = C/T, H = ''not G,'' W = A/T, D = ''not C,'' R =
A/G) (Cui, Y., Wang, Q,, Stormo, G, D,, and Calvo, J, M, (1995) J, Bac
teriol, 177, 4872-4880). Here we report the stoichiometry of Lrp bindi
ng (an Lrp dimer binds to a single binding site) and studies that defi
ne the minimal length of DNA required for binding, A double-stranded 1
5 mer having a sequence that closely matches the consensus does not sh
ow measurable binding to Lrp, One or two base pairs of DNA flanking ea
ch end are not sufficient for binding, but constructs having 3-5 addit
ional base pairs (21 mer) show relatively strong binding, Single-stran
ded flanking DNA also contributes to strong binding, The extent of the
contribution to binding is dependent upon whether the single strand i
s on the left or right of the double stranded region and whether the p
olarity of the single-stranded DNA is 5' to 3' or 3' to 5'.