Are topoisomerases required for mammalian chromosome segregation?
Theoretical considerations indicate that topoisomerase II should be involved in chromosome segregation, since newly replicated daughter DNA molecules must be interwined, and an enzyme such as topoisomerase II is needed to disentangle them. It has been shown, using scanning electron microscopy, that regions of centromeric heterochromatin are the last parts of the chromosomes to separate at anaphase. Such regions generally contain highly repetitive, satellite DNAs, whose function is obscure, since they vary extensively, and apparently randomly, in their sequence and average base composition. However, in spite of this compositional variation, it appears that many satellite DNAs show characteristic curvature, which may, rather than a specific nucleotide sequence, be a recognition site for topoisomerase II. Satellite DNA in centromeric heterochromatin might then, regardless of sequence, provide a specific substrate on which topoisomerase II could act in a concerted fashion at the beginning of anaphase to ensure orderly separation of the daughter chromosomes.
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- Conference: NATO advanced research workshop, Crete (Greece), 10-15 Oct 1992; Other Information: PBD: 1993; Related Information: Is Part Of Chromosome segregation and aneuploidy; Vig, B.K. [ed.] [University of Nevada, Reno, NV (United States). Dept. of Biology]; PB: 429 p.
- Springer-Verlag, New York, NY (United States)
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- United States
- 55 BIOLOGY AND MEDICINE, BASIC STUDIES; ISOMERASES; DNA REPLICATION; CENTROMERES; STRUCTURE-ACTIVITY RELATIONSHIPS; LYMPHOCYTES; MITOSIS; ENZYME INHIBITORS; HETEROCHROMATIN; NUCLEOTIDES; ANTIBODIES; NON-DISJUNCTION; MEIOSIS; SCANNING ELECTRON MICROSCOPY; BIOASSAY