Metaphase chromosome structure is dynamically maintained by condensin I-directed DNA (de)catenation.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 28477406.
- Also identified by DOI 10.7554/eLife.26120 and PMC identifier 5451211.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Mitotic chromosome assembly remains a big mystery in biology. Condensin complexes are pivotal for chromosome architecture yet how they shape mitotic chromatin remains unknown. Using acute inactivation approaches and live-cell imaging in <i>Drosophila</i> embryos, we dissect the role of condensin I in the maintenance of mitotic chromosome structure with unprecedented temporal resolution. Removal of condensin I from pre-established chromosomes results in rapid disassembly of centromeric regions while most chromatin mass undergoes hyper-compaction. This is accompanied by drastic changes in the degree of sister chromatid intertwines. While wild-type metaphase chromosomes display residual levels of catenations, upon timely removal of condensin I, chromosomes present high levels of <i>de novo</i> Topoisomerase II (TopoII)-dependent re-entanglements, and complete failure in chromosome segregation. TopoII is thus capable of re-intertwining previously separated DNA molecules and condensin I continuously required to counteract this erroneous activity. We propose that maintenance of chromosome resolution is a highly dynamic bidirectional process.
Medical subject headings
- Adenosine Triphosphatases
- Chromosome Structures
- DNA
- DNA-Binding Proteins
- Metaphase
- Multiprotein Complexes