ATP-dependent chromatin remodeling enzymes: two heads are not better, just different.
ATP-dependent chromatin remodeling complexes enable rapid rearrangements in chromatin structure in response to developmental cues. The ATPase subunits of remodeling complexes share homology with the helicase motifs of DExx box helicases. Recent single-molecule experiments indicate that, like helicases, many of these complexes use ATP to translocate on DNA. Despite sharing this fundamental property, two key classes of remodeling complexes, the ISWI class and the SWI/SNF class, generate distinct remodeled products. SWI/SNF complexes generate nucleosomes with altered positions, nucleosomes with DNA loops and nucleosomes that are capable of exchanging histone dimers or octamers. In contrast, ISWI complexes generate nucleosomes with altered positions but in standard structures. Here, we draw analogies to monomeric and dimeric helicases and propose that ISWI and SWI/SNF complexes catalyze different outcomes in part because some ISWI complexes function as dimers while SWI/SNF complexes function as monomers.
Racki
Lisa R
LR
Department of Biochemistry and Biophysics, N412F, 600 16th Street, University of California, San Francisco, San Francisco, CA 94158, United States.
Narlikar
Geeta J
GJ
D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D002843:Chromatin / Q000235:genetics* / Q000378:metabolism*; D042002:Chromatin Assembly and Disassembly / Q000235:genetics*; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism; D006801:Humans; D016601:RNA-Binding Proteins / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism
D002843:Chromatin; D002868:Chromosomal Proteins, Non-Histone; D016601:RNA-Binding Proteins; D014157:Transcription Factors; D000255:Adenosine Triphosphate