ATP-dependent positive supercoiling of DNA by 13S condensin: a biochemical implication for chromosome condensation.
basic_science · Level V
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Abstract
13S condensin is a five-subunit protein complex that plays a central role in mitotic chromosome condensation in Xenopus egg extracts. Two core subunits of this complex, XCAP-C and XCAP-E, belong to an emerging family of putative ATPases, the SMC family. We report here that 13S condensin has a DNA-stimulated ATPase activity and exhibits a high affinity for structured DNAs such as cruciform DNA. 13S condensin is able to introduce positive supercoils into a closed circular DNA in the presence of bacterial or eukaryotic topoisomerase I. The supercoiling reaction is ATP-dependent. We propose that 13S condensin wraps DNA in a right-handed direction by utilizing the energy of ATP hydrolysis. This reaction may represent a key mechanism underlying the compaction of chromatin fibers during mitosis.
Medical subject headings
- Adenosine Triphosphatases
- Adenosine Triphosphate
- Carrier Proteins
- Cell Cycle Proteins
- Chromosomal Proteins, Non-Histone
- Chromosomes
- DNA Helicases
- DNA, Superhelical
- DNA-Binding Proteins
- Nuclear Proteins
- Xenopus Proteins