SPECIFIC HISTONE-HISTONE CONTACTS ARE RUPTURED WHEN NUCLEOSOMES UNFOLD AT LOW IONIC-STRENGTH

被引:60
作者
MARTINSON, HG
TRUE, RJ
BURCH, JBE
机构
[1] UNIV CALIF LOS ANGELES,DEPT CHEM,DIV BIOCHEM,LOS ANGELES,CA 90024
[2] UNIV CALIF LOS ANGELES,INST MOLEC BIOL,LOS ANGELES,CA 90024
关键词
D O I
10.1021/bi00573a023
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
The ordered unfolding of the nucleosome core within chromatin at low ionic strengths has been studied. The results show that, when nuclei are lysed gently in solutions of very low ionic strength, their constituent nucleosomes rupture at a major H2B-H4 binding site but remain unperturbed at the site of the H2A-H2B interaction. These conclusions are based on data which show that at least four separate but closely spaced H2B-H4 contacts, identifiable by contact-site cross-linking in intact nuclei, are broken when nuclei are suspended in very dilute buffers. Appropriate controls on purified nucleosome monomers demonstrate that the H2B-H4 contacts being broken are indeed intranucleosomal. Sedimentation of nucleosomes in the ultracentrifuge at various salt concentrations reveals that a significant conformational transition occurs in the range of ionic strength over which the H2B-H4 binding site ruptures. © 1979, American Chemical Society. All rights reserved.
引用
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页码:1082 / 1089
页数:8
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