Inferring the physical properties of yeast chromatin through Bayesian analysis of whole nucleus simulations

• Published in: Genome Biology Vol. 18; no. 1; p. 81
• Main Authors: Arbona, Jean-Michel, Herbert, Sébastien, Fabre, Emmanuelle, Zimmer, Christophe
• Format: Journal Article
• Language: English
• Published: London BioMed Central 03.05.2017; BMC
• Subjects: Animal Genetics and Genomics; Bayes Theorem; Bayesian analysis; Bayesian theory; Bioinformatics; Biomedical and Life Sciences; Cell Nucleus - genetics; Chromatin; Chromatin - chemistry; Chromatin - genetics; Chromatin Assembly and Disassembly; Chromosomes; Computer Simulation; data collection; Deoxyribonucleic acid; DNA; Evolutionary Biology; fiber quality; Gene expression; genome; Genomes; Human Genetics; image analysis; Life Sciences; loci; Mechanical properties; Microbial Genetics and Genomics; Nuclear architecture; physical properties; Plant Genetics and Genomics; Polymer models; polymers; Saccharomyces cerevisiae - genetics; Yeast; yeasts; Chromatin; Polymer models; Yeast; Chromosomes; Nuclear architecture
• ISSN: 1474-760X; 1474-7596; 1465-6906; 1474-760X
• DOI: 10.1186/s13059-017-1199-x

Background The structure and mechanical properties of chromatin impact DNA functions and nuclear architecture but remain poorly understood. In budding yeast, a simple polymer model with minimal sequence-specific constraints and a small number of structural parameters can explain diverse experimental data on nuclear architecture. However, how assumed chromatin properties affect model predictions was not previously systematically investigated. Results We used hundreds of dynamic chromosome simulations and Bayesian inference to determine chromatin properties consistent with an extensive dataset that includes hundreds of measurements from imaging in fixed and live cells and two Hi-C studies. We place new constraints on average chromatin fiber properties, narrowing down the chromatin compaction to ~53–65 bp/nm and persistence length to ~52–85 nm. These constraints argue against a 20–30 nm fiber as the exclusive chromatin structure in the genome. Our best model provides a much better match to experimental measurements of nuclear architecture and also recapitulates chromatin dynamics measured on multiple loci over long timescales. Conclusion This work substantially improves our understanding of yeast chromatin mechanics and chromosome architecture and provides a new analytic framework to infer chromosome properties in other organisms.