Effects of configuration
around the HS2 region on the enhancer activity in transient expression
assay. (A) Effects of replacement of curved DNA
with non-curved DNA on the enhancer activity. Either or both the
nucleosome regions of DNA bend sites, ɛB-16
and ɛB-17, or HS2 site were replaced
with fragments of identical length derived from pBR322 (see Fig.
1 legend). (B) Effects of distance between ɛB-16 and NF-E2 sites on the enhancer
activity. The distance between ɛB-16
and NF-E2 sites was changed by deleting or inserting fragments of
various lengths into the nucleosome linker region next to ɛB-16.
(C) Effects of the orientation of the original
and modified HS2 regions on the enhancer activity. The constructs
HS2R, +80R, +100R, +170R and Δb-16R
contained the same fragments as in HS2, +80, +100, +170
and Δb-16 in the reverse orientation,
respectively. Solid Tc boxes and hatched boxes indicate the non-curved
DNA fragment and Aγ-globin
promoter, respectively. The luciferase activities shown are the
mean values of triplicate assays, and the horizontal bars represent
standard deviations.