High-throughput chromatin motion tracking in living yeast reveals the flexibility of the fiber throughout the genome.
Chromosome dynamics are recognized to be intimately linked to genomic transactions, yet the physical principles governing spatial fluctuations of chromatin are still a matter of debate. Using high-throughput single-particle tracking, we recorded the movements of nine fluorescently labeled chromosome loci located on chromosomes III, IV, XII, and XIV of Saccharomyces cerevisiae over an extended temporal range spanning more than four orders of magnitude (10(-2)-10(3) sec). Spatial fluctuations appear to be characterized by an anomalous diffusive behavior, which is homogeneous in the time domain, for all sites analyzed. We show that this response is consistent with the Rouse polymer model, and we confirm the relevance of the model with Brownian dynamics simulations and the analysis of the statistical properties of the trajectories. Moreover, the analysis of the amplitude of fluctuations by the Rouse model shows that yeast chromatin is highly flexible, its persistence length being qualitatively estimated to <30 nm. Finally, we show that the Rouse model is also relevant to analyze chromosome motion in mutant cells depleted of proteins that bind to or assemble chromatin, and suggest that it provides a consistent framework to study chromatin dynamics. We discuss the implications of our findings for yeast genome architecture and for target search mechanisms in the nucleus.
LAAS, CNRS, F-31400 Toulouse, France;
Houssam
H
Hajjoul
Julien
J
Mathon
Hubert
H
Ranchon
Isabelle
I
Goiffon
Julien
J
Mozziconacci
Benjamin
B
Albert
Pascal
P
Carrivain
Jean-Marc
JM
Victor
Olivier
O
Gadal
Kerstin
K
Bystricky
Aurélien
A
Bancaud
D002467:Cell Nucleus / Q000235:genetics; D002843:Chromatin / Q000378:metabolism*; D015825:Chromosomes, Fungal; D056426:Genetic Loci; D016681:Genome, Fungal; D057166:High-Throughput Screening Assays; D008958:Models, Molecular; D056004:Molecular Dynamics Simulation; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D016615:Telomere / Q000235:genetics
D002843:Chromatin