J. Biol. Chem., Vol. 265, Issue 17, 9909-9913, Jun, 1990
Plant nuclear factor ASF-1 binds to an essential region of the nopaline synthase promoter
E Lam, F Katagiri and NH Chua
Laboratory of Plant Molecular Biology, Rockefeller University, New York, New York 10021.
We have characterized a tobacco nuclear factor that binds to the -118
region of the nopaline synthase (nos) promoter from the Ti plasmid of
Agrobacterium tumefaciens. The binding site for this factor, identified by
DNase I footprinting, encompasses the region from -138 to -103 of the nos
promoter. This region, which contains a potential Z-DNA-forming sequence,
was previously shown to be essential for nos promoter activity in
transgenic tobacco. A synthetic 21-base pair sequence from the protected
region (from -131 to -111), designated as nos-1, was sufficient for factor
recognition in vitro. In transgenic tobacco, a tetramer of nos-1 can confer
leaf and root expression when fused upstream of a truncated 35 S promoter
from the cauliflower mosaic virus. Mutations at the two TGACG-like motifs
in nos-1 abolish factor binding while preserving the potential for Z-DNA
formation. A tetramer of the nos-1 mutant sequence has no significant
activity above background when tested in transgenic tobacco. Competition
experiments with activation sequence factor (ASF)-1 binding sites from the
35 S promoter of cauliflower mosaic virus (as-1) and the wheat histone H3
promoter (hex-1) demonstrate that ASF-1 is the factor that binds to nos- 1.