['Z-DNA is a higher-energy, left-handed form of the double helix. A primary function of Z-DNA formation is to facilitate transcriptional initiation and activation. Sequences favoring Z-DNA formation are frequently located in promoter regions and Z-DNA is stabilized by torsional strain resulting from negative supercoiling, such as that generated by an actively transcribing polymerase or by a nucleosome remodeling event. We previously have shown that activation of the CSF1 gene by a chromatin remodeling event in the promoter results in Z-DNA formation at TG repeats within the promoter.', 'We show that remodeling of a mononucleosome by the human SWI/SNF complex results in Z-DNA formation when the DNA within the mononucleosome contains Z-DNA favoring sequence. Nuclease accessibility patterns of nucleosome core particle consisting of Z-DNA are quite different from counterpart nucleosomes containing classic B-DNA. Z-nucleosomes represent a novel mononucleosome structure.'] Does sWI/SNF-mediated chromatin remodeling induce Z-DNA formation on a nucleosome?