Budding yeast chromatin is dispersed in a crowded nucleoplasm in vivo.
Chromatin organization has an important role in the regulation of eukaryotic systems. Although recent studies have refined the three-dimensional models of chromatin organization with high resolution at the genome sequence level, little is known about how the most fundamental units of chromatin-nucleosomes-are positioned in three dimensions in vivo. Here we use electron cryotomography to study chromatin organization in the budding yeast Saccharomyces cerevisiae Direct visualization of yeast nuclear densities shows no evidence of 30-nm fibers. Aside from preribosomes and spindle microtubules, few nuclear structures are larger than a tetranucleosome. Yeast chromatin does not form compact structures in interphase or mitosis and is consistent with being in an "open" configuration that is conducive to high levels of transcription. From our study and those of others, we propose that yeast can regulate its transcription using local nucleosome-nucleosome associations.
Department of Biological Sciences and Centre for BioImaging Sciences, National University of Singapore, Singapore 117543, Singapore.
Chen
C
Chen
Institute of Molecular and Cell Biology, Agency for Science Technology and Research, Proteos, Singapore 138673, Singapore.|Bioprocessing Technology Institute, Singapore 138668, Singapore.
Hong Hwa
HH
Lim
Department of Biological Sciences and Centre for BioImaging Sciences, National University of Singapore, Singapore 117543, Singapore.
Jian
J
Shi
National Institute of Genetics and Sokendai, Graduate University for Advanced Studies, Mishima, Shizuoka 411-8540, Japan.
Sachiko
S
Tamura
National Institute of Genetics and Sokendai, Graduate University for Advanced Studies, Mishima, Shizuoka 411-8540, Japan.
Kazuhiro
K
Maeshima
Institute of Molecular and Cell Biology, Agency for Science Technology and Research, Proteos, Singapore 138673, Singapore.|Bioprocessing Technology Institute, Singapore 138668, Singapore.|Department of Pharmacology, National University of Singapore, Singapore 117543, Singapore.
Uttam
U
Surana
Department of Biological Sciences and Centre for BioImaging Sciences, National University of Singapore, Singapore 117543, Singapore lu@anaphase.org.
Lu
L
Gan
D002467:Cell Nucleus; D002843:Chromatin / Q000378:metabolism* / Q000502:physiology* / Q000648:ultrastructure; D008938:Mitosis; D009707:Nucleosomes / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics; D004718:Saccharomycetales / Q000235:genetics; D014054:Tomography
D002843:Chromatin; D009707:Nucleosomes; D029701:Saccharomyces cerevisiae Proteins