Histone cross-complexing pattern

Abstract

al residues per tetramer go into an -helical conformation. Complexing inhibits the slow aggregation of ARE and GRK. Histones ARE and LAK also interact in a 1:1 molar ratio, but there is no increased a helicity upon complexing, and slow aggregation and /3-sheet formation occur. ARE and KAS also interact, but, upon complexing, there is no change in the tyrosine rigidity or in the circular dichroism. A pattern of the interactions between LAK, KAS, ARE, and GRK is presented. more weakly (D'Anna and Isenberg, 1974a). The complexes require salt for stability and, in fact, they were formed by adding salt to histone mixtures in water. One or both of the partner histones in the strong complexes, KAS-GRK and LAK-KAS, show marked conformational changes upon complexing, and the complex shows considerably more -helical content than the uncomplexed molecules.Skandrani et al. (1972) and Kelley (1973) have also reported a 1:1 complex of histones LAK and KAS, which was isolated by chromatographic fractionation of mixed his-4992 BIOCHEMISTRY, VOL.

Conformational Studies of Two Non‐histone Chromosomal Proteins and Their Interactions with DNA

“…When high-mobility-group protein 1 is titrdted much above pH 6 (at the 10 mg/ml concentration used for the NMR measurements) there is considerable peak broadening in the NMR spectrum due to aggregation (Fig. 4) above pH 9 as the secondary and tertiary structure breaks up.…”

“…Of the five main histone fractions, all but the most lysinerich (Hl) are observed to take up a partially helical structure on salt addition at pH 3-4 with the simultaneous formation of inter-histone aggregates that include most of the molecule but leave the most basic terminal regions free in the solution. The aggregating capacity of the individual histones is probably related to a functional self-assembly property and recent results on associations between histones of different type strongly support the concept of histone selfassembly [6]. An increase in the pH from 3-7 does not by itself induce large structural changes in the conformation of these four histones but this is not found to be the case with H1 which is observed to form both secondary and tertiary structure on pH increase without any concomitant aggregation [7].…”

Closely Spaced Nucleosome Cores in Reconstituted Histone . DNA Complexes and Histone-H1-Depleted Chromatin

“…The concentrations of nuclei were determined by measuring the 260-nm absorption in 2 M NaCI, 5 M urea. Histone concentrations were measured spectrophotometrically at 275 nm using the absorption coefficients given by D'Anna and Isenberg [40] TA, P, buffcr (saturated with chloroform) and a n a l )~c d on ;I 2 arose slab gel in Tris,'EDTA,'Pi buffer [41]. The gel w i i \ \[:tined uith ethidium bromide and photographed in ultraviolet light i t \ described [42].…”

The reconstitution of histone H3H4 tetramer from acid extracted histones in the absence of urea

“…Though core particle like structures have been prepared from acid extracted histones [16], the yield of such particles cannot be gleaned from the reports. In the reconstitution experiment reported here the histone concentration is between 100-200 times larger than used previously in the literature (9,101. Under the present conditions only the salt extracted natural H3-I$ complex exists solely in the form of the tetramer, the acid extracted H3 and H4 histones form an aggregate larger than 20 S. When however a mixture of all the acid extracted core histones (or total histones) are exposed first to conditions known to allow octamer formation and then subsequently subjected to a decrease in the salt concentration, formation of a H3-H4 tetramer occurs though still approximately 20% of the histones H3 and & aggregate to a size larger than 20 S. This aggregation may well be the result of misdirected protein-protein interactions.…”

“…Hydrodynamic [ 111, electrophoretic [ 121 and spectroscopic evidence [9] has been provided to show that the degree of denaturation may be only slight and easily reversible. Alternatively irreversible reduction of helix content [13] The typical X-ray diffraction pattern characterising the repeat structure of chromatin could only be produced after reassembly from salt extracted histones 1151.…”