Histone Sin mutations promote nucleosome traversal and histone displacement by RNA polymerase II

Department of Pharmacology, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, 675 Hoes Lane, Piscataway, New Jersey 08854, USA.
EMBO Reports (Impact Factor: 7.86). 09/2010; 11(9):705-10. DOI: 10.1038/embor.2010.113
Source: PubMed

ABSTRACT Nucleosome traversal by RNA polymerase II (pol II) and recovery of chromatin structure after transcription are essential for proper gene expression. In this paper we show that nucleosomes assembled with Sin mutant histones present a much weaker barrier to traversal by pol II and are less likely to survive transcription. Increases in traversal from incorporation of Sin mutant histones and histones lacking H2A/H2B amino-terminal tails were in most cases additive, indicating that traversal can be facilitated by distinct mechanisms. We had identified a key intermediate in traversal, the zero (slashed circle)-loop, which mediates nucleosome survival during transcription. Sin mutations probably destabilize these intermediates and thus increase the likelihood of nucleosome disassociation.