Mapping in vivo chromatin interactions in yeast suggests an extended chromatin fiber with regional variation in compaction
Dekker, Job
Citations
Authors
Student Authors
Faculty Advisor
Academic Program
UMass Chan Affiliations
Document Type
Publication Date
Keywords
Chromosomes
Cross-Linking Reagents
Fungal Proteins
Models, Statistical
Models, Theoretical
Molecular Conformation
Normal Distribution
Nucleosomes
Protein Binding
Protein Conformation
Protein Structure, Tertiary
Saccharomyces cerevisiae
Temperature
Transcription, Genetic
Genetics and Genomics
Subject Area
Embargo Expiration Date
Link to Full Text
Abstract
The higher order arrangement of nucleosomes and the level of compaction of the chromatin fiber play important roles in the control of gene expression and other genomic activities. Analysis of chromatin in vitro has suggested that under near physiological conditions chromatin fibers can become highly compact and that the level of compaction can be modulated by histone modifications. However, less is known about the organization of chromatin fibers in living cells. Here, we combine chromosome conformation capture (3C) data with distance measurements and polymer modeling to determine the in vivo mass density of a transcriptionally active 95-kb GC-rich domain on chromosome III of the yeast Saccharomyces cerevisiae. In contrast to previous reports, we find that yeast does not form a compact fiber but that chromatin is extended with a mass per unit length that is consistent with a rather loose arrangement of nucleosomes. Analysis of 3C data from a neighboring AT-rich chromosomal domain indicates that chromatin in this domain is more compact, but that mass density is still well below that of a canonical 30 nm fiber. Our approach should be widely applicable to scale 3C data to real spatial dimensions, which will facilitate the quantification of the effects of chromatin modifications and transcription on chromatin fiber organization.
Source
J Biol Chem. 2008 Dec 12;283(50):34532-40. Epub 2008 Oct 16. Link to article on publisher's site