DNA loops generate intracentromere tension in mitosis.
The centromere is the DNA locus that dictates kinetochore formation and is visibly apparent as heterochromatin that bridges sister kinetochores in metaphase. Sister centromeres are compacted and held together by cohesin, condensin, and topoisomerase-mediated entanglements until all sister chromosomes bi-orient along the spindle apparatus. The establishment of tension between sister chromatids is essential for quenching a checkpoint kinase signal generated from kinetochores lacking microtubule attachment or tension. How the centromere chromatin spring is organized and functions as a tensiometer is largely unexplored. We have discovered that centromere chromatin loops generate an extensional/poleward force sufficient to release nucleosomes proximal to the spindle axis. This study describes how the physical consequences of DNA looping directly underlie the biological mechanism for sister centromere separation and the spring-like properties of the centromere in mitosis.
Department of Biology, University of North Carolina, Chapel Hill, NC 27599.
Josh
J
Lawrimore
Department of Mathematics, University of South Carolina, Columbia, SC 29208.
Paula A
PA
Vasquez
Department of Physics and Astronomy, University of North Carolina, Chapel Hill, NC 27599.
Michael R
MR
Falvo
Department of Computer Science, University of North Carolina, Chapel Hill, NC 27599.
Russell M
RM
Taylor
Department of Computer Science, University of North Carolina, Chapel Hill, NC 27599.
Leandra
L
Vicci
Department of Biology, University of North Carolina, Chapel Hill, NC 27599.
Elaine
E
Yeh
Department of Mathematics and Biomedical Engineering, University of North Carolina, Chapel Hill, NC 27599.
M Gregory
MG
Forest
Department of Biology, University of North Carolina, Chapel Hill, NC 27599 Kerry_Bloom@unc.edu.
Kerry
K
Bloom
D002503:Centromere / Q000502:physiology* / Q000648:ultrastructure; D002843:Chromatin / Q000502:physiology / Q000648:ultrastructure; D004271:DNA, Fungal / Q000502:physiology / Q000648:ultrastructure; D008870:Microtubules / Q000378:metabolism; D008938:Mitosis; D009690:Nucleic Acid Conformation; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000235:genetics*; D008941:Spindle Apparatus
D002843:Chromatin; D004271:DNA, Fungal