Evidence for DNA translocation by the ISWI chromatin-remodeling enzyme.
The ISWI proteins form the catalytic core of a subset of ATP-dependent chromatin-remodeling activities. Here, we studied the interaction of the ISWI protein with nucleosomal substrates. We found that the ability of nucleic acids to bind and stimulate the ATPase activity of ISWI depends on length. We also found that ISWI is able to displace triplex-forming oligonucleotides efficiently when they are introduced at sites close to a nucleosome but successively less efficiently 30 to 60 bp from its edge. The ability of ISWI to direct triplex displacement was specifically impeded by the introduction of 5- or 10-bp gaps in the 3'-5' strand between the triplex and the nucleosome. In combination, these observations suggest that ISWI is a 3'-5'-strand-specific, ATP-dependent DNA translocase that may be capable of forcing DNA over the surface of nucleosomes.
Whitehouse
Iestyn
I
Division of Gene Regulation and Expression, The Wellcome Trust Biocentre, Department of Biochemistry, University of Dundee, Dundee DD1 5EH, Scotland, UK.
Stockdale
Chris
C
Flaus
Andrew
A
Szczelkun
Mark D
MD
Owen-Hughes
Tom
T
D000251:Adenosine Triphosphatases / Q000502:physiology*; D000255:Adenosine Triphosphate / Q000502:physiology; D020816:Amino Acid Motifs; D000818:Animals; D001667:Binding, Competitive; D002384:Catalysis; D002843:Chromatin / Q000378:metabolism*; D004247:DNA / Q000378:metabolism / Q000494:pharmacology; D004277:DNA, Single-Stranded / Q000378:metabolism / Q000494:pharmacology; D029721:Drosophila Proteins / Q000502:physiology*; D004331:Drosophila melanogaster / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D046911:Macromolecular Substances; D009690:Nucleic Acid Conformation; D009707:Nucleosomes / Q000378:metabolism; D009841:Oligonucleotides / Q000378:metabolism; D011485:Protein Binding; D013379:Substrate Specificity
D002843:Chromatin; D004277:DNA, Single-Stranded; D029721:Drosophila Proteins; D046911:Macromolecular Substances; D009707:Nucleosomes; D009841:Oligonucleotides; C051802:triplex DNA; D000255:Adenosine Triphosphate; D004247:DNA; D000251:Adenosine Triphosphatases