Nucleosomal fluctuations govern the transcription dynamics of RNA polymerase II.
RNA polymerase II (Pol II) must overcome the barriers imposed by nucleosomes during transcription elongation. We have developed an optical tweezers assay to follow individual Pol II complexes as they transcribe nucleosomal DNA. Our results indicate that the nucleosome behaves as a fluctuating barrier that locally increases pause density, slows pause recovery, and reduces the apparent pause-free velocity of Pol II. The polymerase, rather than actively separating DNA from histones, functions instead as a ratchet that rectifies nucleosomal fluctuations. We also obtained direct evidence that transcription through a nucleosome involves transfer of the core histones behind the transcribing polymerase via a transient DNA loop. The interplay between polymerase dynamics and nucleosome fluctuations provides a physical basis for the regulation of eukaryotic transcription.
Hodges
Courtney
C
Jason L. Choy Laboratory of Single-Molecule Biophysics and Biophysics Graduate Group, University of California, Berkeley, CA 94720, USA.
Bintu
Lacramioara
L
Lubkowska
Lucyna
L
Kashlev
Mikhail
M
Bustamante
Carlos
C
D020029:Base Pairing; D020134:Catalytic Domain; D004247:DNA / Q000235:genetics / Q000378:metabolism*; D004058:Diffusion; D006657:Histones / Q000378:metabolism; D008957:Models, Genetic; D009707:Nucleosomes / Q000378:metabolism*; D052898:Optical Tweezers; D012319:RNA Polymerase II / Q000737:chemistry / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D013698:Templates, Genetic; D014158:Transcription, Genetic
D006657:Histones; D009707:Nucleosomes; D012333:RNA, Messenger; D004247:DNA; D012319:RNA Polymerase II