2009/07/30 by H. Courtney Hodges, Lacramioara Bintu, Lucyna Lubkowska +2 · 2 citations
Biochemistry, Genetics and Molecular Biology · #Genomics and Chromatin Dynamics #DNA and Nucleic Acid Chemistry #RNA and protein synthesis mechanisms
paper · doi:10.1126/science.1172926
openalex publication_date 2009/07/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
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.