Open AccessEnhanced transcription factor access to arrays of histone H3/H4 tetramer⋅DNA complexes in vitro : Implications for replication and transcription
Author(s) -
Christin Tse,
Terace M. Fletcher,
Jeffrey C. Hansen
Publication year - 1998
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.95.21.12169
Subject(s) - histone , dna replication , transcription (linguistics) , microbiology and biotechnology , origin recognition complex , replication factor c , dna , histone h3 , genetics , biology , tetramer , chemistry , eukaryotic dna replication , biochemistry , linguistics , philosophy , enzyme
Defined model systems consisting of physiologically spaced arrays of H3/H4 tetramer⋅5S rDNA complexes have been assembledin vitro from pure components. Analytical hydrodynamic and electrophoretic studies have revealed that the structural features of H3/H4 tetramer arrays closely resemble those of naked DNA. The reptation in agarose gels of H3/H4 tetramer arrays is essentially indistinguishable from naked DNA, the gel-free mobility of H3/H4 tetramer arrays relative to naked DNA is reduced by only 6% compared with 20% for nucleosomal arrays, and H3/H4 tetramer arrays are incapable of folding under ionic conditions where nucleosomal arrays are extensively folded. We further show that the cognate binding sites for transcription factor TFIIIA are significantly more accessible when the rDNA is complexed with H3/H4 tetramers than with histone octamers. These results suggest that the processes of DNA replication and transcription have evolved to exploit the unique structural properties of H3/H4 tetramer arrays.