J. Biol. Chem., Vol. 261, Issue 24, 11202-11206, 08, 1986
Promoter recognition by Escherichia coli RNA polymerase. Effects of substitutions in the spacer DNA separating the -10 and -35 regions
DT Auble, TL Allen and PL deHaseth
A family of variants of the PRM promoter of lambda phage was constructed,
bearing nine base pair substitutions in a stretch of the spacer DNA
separating the contacted -10 and -35 regions. The substituted sequences
were chosen for their potential to adopt structures different from those of
average B-form DNA and thus to affect the interaction of RNA polymerase
with the two contacted regions. Characterization of the promoters in vitro
and in vivo provides additional support for the lack of specific contacts
in the substituted spacer region and shows that a small change in the
relative rotational orientation of the -10 and -35 regions is
inconsequential to promoter function. However, a 2-3-fold reduction in
promoter activity is observed with promoters bearing substitutions of
nonalternating dG- dC base pairs in either orientation. This corroborates
other studies indicating the anomalous behavior of such sequences and
suggests that the structure of the spacer DNA can modulate promoter
recognition.