Kinetic Mechanism for Single stranded DNA binding and Translocation by S. cerevisiae Isw2
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Issue Date
2009-04-07Author
Fischer, Christopher J.
Yamada, Kazuhiro
Fitzgerald, Daniel J.
Publisher
ACS
Type
Article
Article Version
Scholarly/refereed, author accepted manuscript
Rights
Copyright © 2009 American Chemical Society
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Show full item recordAbstract
The chromatin remodeling complex Isw2 from S. cerevisiae (yIsw2) mobilizes nucleosomes through an ATP-dependent reaction that is coupled to the translocation of the helicase domain of the enzyme along intranucleosomal DNA. In this study we demonstrate that yIsw2 is capable of translocating along single-stranded DNA in a reaction that is coupled to ATP hydrolysis. We propose that single-stranded DNA translocation by yIsw2 occurs through a series of repeating uniform steps with an overall macroscopic processivity of P = (0.90 ± 0.02), corresponding to an average translocation distance of (20 ± 2) nucleotides before dissociation. This processivity corresponds well to the processivity of nucleosome sliding by yIsw2 thus arguing that single-stranded DNA translocation or tracking may be fundamental to the double-stranded DNA translocation required for effective nucleosome mobilization. Furthermore, we find evidence that a slow initiation process, following DNA binding, may be required to make yIsw2 competent for DNA translocation. We also provide evidence that this slow initiation process may correspond to the second step of a two-step DNA binding mechanism by yIsw2 and a quantitative description of the kinetics of this DNA binding mechanism.
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Citation
Fischer, C. J., Yamada, K., & Fitzgerald, D. J. (2009). Kinetic Mechanism for Single stranded DNA binding and Translocation by S. cerevisiae Isw2. Biochemistry, 48(13), 2960–2968. http://doi.org/10.1021/bi8021153
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