Histones F2a1 and F3 interact reversibly and cooperatively with DNA to form an equimolar complex in chromatin

Nucleosome structure

“…A brupt dilutions above 1.4 m NaCl did not result in any H 3-H 4 subnucleosomal particles (unpublished results). This formation of H 3-H 4 particles at approximately 1.2 m NaCl is interesting in two respects: first, because it has previously been shown that 1.2-1.4 m NaCl is precisely the range of salt concentration at which histones H 3 and H 4 dissociate reversibly and cooperatively as an equimolar complex from calf thymus chromatin DNA (Burton, Hyde & Walker 1975; secondly, because we have previously reported that the histone core of the nucleosome, which comprises all four histones H2A, H2B, H 3 and H 4, dissociate reversibly from the DNA at 0.8-0.9 m NaCl ). It appears therefore that the affinity of histones H 3 and H 4 for the DNA could be lowered by their association to histones H2A and H2B.…”

The interaction of core histones with DNA: equilibrium binding studies

“…2 and refs. [3,12]). Dissociated Hl is always present in the system during the dissociation and re-association of the other four core histones.…”

“…In high salt there is a tendency for the histone to dissociate from the depleted chromatin peak which leads to a variation of histone to DNA ratio across the depleted chromatin peak. However, the histone-DNA ratio of the original depleted chromatin may be obtained by pooling all fractions across the peak and measuring the average histone-DNA content [12]. Chromatin (0.1-1.0 mg/ml) in 0.7 mM sodium phosphate, pH 7.0, was dialysed for 3 hours against salt solutions at either 4°C or 200C.…”

“…An analysis of the histone types which are dissociated over the range 1.2 to 2.0 M NaCl by gel electrophoresis has shown that H3 and H4 are dissociated and reassociated in equimolar amounts, probably as an equimolar com- plex, which must therefore be at least a dimer [12]. This result is supported by crosslinking studies of H3-H4 DNA in 2 M NaCl which show that the histones exist as heterotypic dimers, tetramers and higher polymers;[3]-.…”

The "Condensation-Decondensation" of Chromatin as Related to Chromosomal Structure: A System Examining Various Conditions Affecting Fractionation of Chromatin

“…(52)(53)(54)(55). Also, treat-ment of chromatin with specific crossi inking agents followed by removal and identification of the cross-linked products has presented evidence which indicates that these two histones are associated in chromatin (159)(160)(161).…”