Wrapping of genomic polydA.polydT tracts around nucleosome core particles

Fox, Keith R. (1992) Wrapping of genomic polydA.polydT tracts around nucleosome core particles. Nucleic Acids Research, 20 (6), 1235-1242. (doi:10.1093/nar/20.6.1235).

Record type: Article

Abstract

Five human clones containing genomic regions of polydA have been isolated by their ability to form intermolecular triple helices with agarose cross-linked polyU. All of these clones contain Alu repetitive DNA sequences. End-labelled DNA fragments containing these sequences have been successfully reconstituted onto nucleosome core particles by salt exchange. The structure of these has been examined by digesting with DNase I, hydroxyl radicals or diethylpyrocarbonate. DNase I cleavage of the polydA tracts is poor in the free DNA but is markedly enhanced at certain positions when complexed with nucleosome cores. Phased digestion patterns are observed which continue through the (A)_n blocks and reveal an average helical periodicity of about 10 base pairs. The distance between adjacent maxima varies between 8-12 base pairs, suggesting that the exact helical repeat is not necessarily constant. One fragment containing the sequence (TA)₁₁T₃₄ reveals a 12 base pair repeat within the (AT)_n region. A pUC19 polylinker fragment containing a block of A₆₉.T₆₉ cloned into the Smal site could also be reconstituted onto nucleosome cores and reveals the same phased DNasel digestion pattern. The DNase I cleavage pattern is not identical at each of the maxima, suggesting that the structural distortions imposed by the core particles are not constant along the DNA.

This record has no associated files available for download.

More information

Published date: 25 March 1992

Additional Information: Funding Information: This work was supported by the Lister Institute for Preventive Medicine. KRF is a Lister Institute Research Fellow.