Walter N. Strickland

More histone structures

Since the elucidation of the amino acid sequence of the prototype histones H3, H4, H2A and H2B, a considerable amount of information on the occurrence of variants of these structures has become available. (Bibliographic references to details of the histone primary structures are given in fig.l-3; for review see [341.) It appears that the histones H3 and H4, over a wide range of evolution, vary only slightly whereas the histones H2A and H2B undergo more extensive evolutionary changes (fig.1 -3). The variations of the structures can be classified into two types. The first group comprises simple point mutations or deletions of one or several residues. The second type of structural variations consists in extensive modifications of major areas of the molecules through reiteration, insertion, deletion and point mutations. Such changes have led, in some variants, to the establishment of new domains in the structure. Whereas the former type of structure variation occurs in all four histones, the second group of more extensive variations up to now has been identified only in the histones of the H2A and H2B type. The first group of alterations does not change the general structure of the molecules drastically. Such changes occur infrequently in the histones H3 and H4. In histone H3, four positions are variable. In the histone H4 only three variable positions have been identified. In both these histones there appears to be no regional preference for the conservative point mutations. The mutations involving cysteine in position 96 of

The partial amino acid sequences of the two H2B histones from sperm of the sea urchin Psammechinus miliaris

Two new histone H2B variants have been isolated from sperm cells of the sea urchin Psammechinus miliaris. They have been designated sperm histone H2B(1) Psammechinus and sperm histone H2B(2) Psammechinus. Both histones are highly homologous to the previously described sperm histones from Parechinus angulosus (Strickland et al. (1977) Eur. J. Biochem. 77, 263--275 and 277--286). The amino acid sequences of the Ps. miliaris sperm histones, though highly homologous, are not identical to the amino acid sequence derived from the codon sequence of a histone H2B gene, characterized from the same organism by Birnstiel et al. ((1977) Nature 266, 603--607).

A partial structure of histone H1 from sperm of the sea urchin sphaerechinus granulosus

Abstract 91 amino acids from sperm H1 histone of the sea urchin Sphaerechints angulosus have been placed in sequence. 24 of these amino acids are in the amino-terminal random-coil region of histone H1, while the remaining 67 amino acids comprise the central hydrophobic globular region. The sequence is compared to that of other H1 histones from various species.

The occurrence of sperm isohistones H2B in single sea urchins

The complete amino acid sequences of three H2B histones from the sperm cells ofParechinus angulosus have been reported [ 1 -3] . These proteins were purified from pooled samples o f sperm. The sperm from animals collected at various locations all contained H2B1 but varied in the relative amounts o f H2Bz and H2B3. This prompted an investigation to determine whether the 3 isohistone genes for the sperm cell-specific histones H2B are expressed simultaneously in one organism. Such information may help to reveal the significance of the occurrence of these isohistones.

The complete amino-acid sequence of histone H2B from erythrocytes of the adult domestic fowl gallus domesticus☆

Abstract From the erythrocytes of the domestic fowl a histone H2B bas been isolated. Its primary structure has been determined. It shows a very high degree of sequence homology to calf thymus histone H2B, with identical residues in 119 out of the 125 positions.

The identification by sequence homology of stage-specific sea urchin embryo histones H1

The histone H1 fraction from gastrula of the sea urchin Parechinus angulosus consists of a multitude of polypeptides with different electrophoretic mobilities. The synthesis of these proteins is programmed. Amino acid composition, electrophoretic properties and sequence homologies identify these as isohistones H1. One of these isohistones atypically binds the non-ionic detergent Triton X-100.