|
The SWI/SNF complex is required for the enhancement of
transcription by many transcriptional activators in yeast.
Genetic and biochemical studies indicate that the complex
facilitates activator function by antagonizing
chromatin-mediated transcriptional repression. The absence
of known DNA-binding motifs in several SWI/SNF subunits and
the failure to identify SWI/SNF-dependent DNA-binding
activities in crude yeast extracts have led to the belief
that the complex does not bind DNA. Here we show that the
SWI/SNF complex has a high affinity for DNA and that its
DNA-binding properties are similar to those of proteins
containing HMG-box domains. The complex interacts with the
minor groove of the DNA helix, binds synthetic four-way
junction DNA, and introduces positive supercoils into
relaxed plasmid DNA. These properties are likely to be
important in the remodelling of chromatin structure by the
SWI/SNF complex |
