Facilitated Transcription through the Nucleosome at High Ionic Strength Occurs via a Histone Octamer Transfer Mechanism

The rate of transcription through the nucleosome, the fine structure of the nucleosomal barrier, and the fate of the nucleosome during transcription at different salt concentrations were analyzed using linear 227-base pair mononucleosomal templates containing a uniquely positioned nucleosome core. A...

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Bibliographic Details
Published in:The Journal of biological chemistry 2001-08, Vol.276 (31), p.29104-29110
Main Authors: Walter, W, Studitsky, V M
Format: Article
Language:English
Subjects:
Animals
Chickens
Dimerization
DNA-Directed RNA Polymerases - metabolism
Erythrocytes - metabolism
Histones - metabolism
Models, Biological
Nucleosomes - drug effects
Nucleosomes - genetics
Osmolar Concentration
Plasmids
Promoter Regions, Genetic
Protein Transport
Saline Solution, Hypertonic - pharmacology
Templates, Genetic
Transcription, Genetic - drug effects
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Summary:The rate of transcription through the nucleosome, the fine structure of the nucleosomal barrier, and the fate of the nucleosome during transcription at different salt concentrations were analyzed using linear 227-base pair mononucleosomal templates containing a uniquely positioned nucleosome core. At lower ionic strength (30 m m NaCl), the nucleosome constitutes a strong barrier for SP6 RNA polymerase. At higher ionic strength (330 m m NaCl), the rates of transcription on nucleosomal and histone-free DNA templates are very similar. At both higher and lower ionic strengths, the complete histone octamer is transferred over the same distance by fundamentally similar mechanisms. The data indicate that even at the rate of transcription characteristic of histone-free DNA, the transfer intermediates can be formed quite efficiently. This suggests possible mechanisms that could facilitate transcription through the nucleosome at physiological ionic strength.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.M103704200