A looped intermediate leads to remodeling of a nucleosome.

Bartholomew/Elsevier

Remodeling by the SWI/SNF complex involves peeling and rewrapping of the DNA that winds around the histone octamer, according to Stefan Kassabov, Blaine Bartholomew, and colleagues (Southern Illinois University, Carbondale, IL).

Most models for SWI/SNF remodeling have been based on assays that measure either the accessibility of DNA to nucleases or the level of DNA supercoiling. The Illinois team, however, directly measured where specific sites on the histone octamer surface contact DNA before and after remodeling by attaching photoreactive groups to sites within the histone fold regions.

SWI/SNF displaced the histone octamers so that they were hanging on to only about 100 bp of DNA as compared to the normal 146 bp. “The fact that it can move an extra 50 bp beyond the end says that it is not just sliding by pushing the...

The Rockefeller University Press
2003
The Rockefeller University Press
2003
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