Real-time detection of single-molecule DNA compaction by condensin I

Strick, T. R., Kawaguchi, T., Hirano, T. (2004) Real-time detection of single-molecule DNA compaction by condensin I. Curr Biol, 14 (10). pp. 874-80. ISSN 0960-9822 (Print)

URL: http://www.scopus.com/record/display.url?eid=2-s2....
DOI: 10.1016/j.cub.2004.04.038

Abstract

BACKGROUND: Condensin is thought to contribute to large-scale DNA compaction during mitotic chromosome assembly. It remains unknown, however, how the complex reconfigures DNA structure at a mechanistic level. RESULTS: We have performed single-molecule DNA nanomanipulation experiments to directly measure in real-time DNA compaction by the Xenopus laevis condensin I complex. Condensin can bind to the nanomanipulated DNA in the absence of ATP, but it compacts the DNA only in the presence of hydrolyzable ATP. Linear compaction is evidenced by a reduction in the end-to-end extension of nanomanipulated DNA. The reaction results in total compaction of the DNA (i.e., zero end-to-end extension). Discrete and reversible DNA compaction events are observed in the presence of competitor DNA when the DNA is subjected to weak stretching forces (F = 0.4 picoNewton [pN]). The distribution of step sizes is broad and displays a peak at approximately 60 nm ( approximately 180 bp) as well as a long tail. This distribution is essentially unaffected by the topological state of the DNA substrate. Increasing the force to F = 10 pN drives the system toward step-wise reversal of compaction. The distribution of step sizes observed upon disruption of condensin-DNA interactions displays a sharp peak at approximately 30 nm ( approximately 90 bp) as well as a long tail stretching out to hundreds of nanometers. CONCLUSIONS: The DNA nanomanipulation assay allows us to demonstrate for the first time that condensin physically compacts DNA in an ATP-hydrolysis-dependent manner. Our results suggest that the condensin complex may induce DNA compaction by dynamically and reversibly introducing loops along the DNA.

Item Type: Paper
Uncontrolled Keywords: Adenosine Triphosphatases metabolism DNA nanomanipulation Adenosine Triphosphate metabolism Animals Chromatography Affinity DNA metabolism DNA-Binding Proteins metabolism Multiprotein Complexes Nanotechnology Nucleic Acid Conformation Xenopus laevis
Subjects: bioinformatics > genomics and proteomics > genetics & nucleic acid processing > protein structure, function, modification > protein types > condensin complex
organs, tissues, organelles, cell types and functions > organelles, types and functions > mitosis
CSHL Authors:
Depositing User: CSHL Librarian
Date Deposited: 25 Jan 2012 14:58
Last Modified: 25 Jan 2012 14:58
URI: http://repository.cshl.edu/id/eprint/22493

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