No abstract

The primary structure of sperm histone H1parecrJinus has been determined. H1par,c~Jinus consists of a polypeptide chain of the following 248 amino acid residues : Pro-Gly-Ser-Pro-Gln-Lys-Arg-Ala-AlaSer-Pro-Arg-Lys-Ser-Pro-Arg-Lys-Ser-Pro-Lys-Lys-Ser-Pro-Arg-Lys-Ala-Ser-Ala-Ser-Pro-Ala-Lys-Ala-Ala-Ala-Lys-Arg -Lys-Ala-Ala-Leu-Ala-LysLys-Lys -Ala-Ala-Ala-Ala-Lys-Arg-Lys-Ala-Ala -Ala-Lys -Ala-Lys -Lys-Ala-Lys-Lys -Pro -LysLys-Lys-Ala-Ala-Lys-Lys-Ala-Lys-Lys-Pro-Ala-Lys-Lys-Ser-Pro-Lys-Lys-Ala-Lys-Lys-ProAla-Lys-Lys-Ser-Pro-Lys-Lys-Lys-Lys-Ala-Lys-Arg-Ser-Pro-Lys-Lys-Ala-Lys-Lys-Ala-Ala-Ser-Pro-Lys-Lys-Ala-Arg-Lys. The protein consists of three domains. Compared to other HI and H5 histones, there is a very similar hydrophobic central domain and the carboxyl-terminal domain is very rich in lysine and alanine. Hlparectrcnus is similar to H5 histones in that the carboxyl-terminal domain also contains many arginine residues close to the carboxyl terminus. The carboxyl-terminal domain of HI P~~~~F~,~~ appears to have been constructed by a series of variable duplications. The amino-terminal domain of H~P~~~~J ,~~~~ is longer and quite different to that of other HI and H5 histones and is characterized by a repeating tetrapeptide of the general type Ser-Pro-(basic)z.The known sequence of a histone H1 gene from Psammechinus miliaris [Schaffner, W. et al. (1978) Cell, 14, 655-6711 is compared to the sequence of H1parecfJinus. Again the central hydrophobic domains are similar whereas the amino terminal domains are very different. Arg LysThe functions of the various domains of sperm histone H1parec~linus are discussed.In the preceding paper [l] the sequence of the first 84 residues of the sea urchin histone H1 have been reported. That investigation included a set of four cyanogen bromide fragments generated from the N-terminal region of the protein. The fifth CNBr peptide, CN-I, comprises 169 residues out of a total of 248 in the protein. The composition of CN-I is unusual insofar as 49 residues are alanine and 75 lysine and arginine. Such a composition indicates the presence of rather monotonous sequences, consisting possibly of an arrangement of reiterations of alanine lysine-rich stretches.Only few handles for breaking up this large cyanogen bromide fragment became evident from the composition of the fragment. The elucidation of the primary structure of this 169-residue fragment to be

It has been observed that proline are considerable differences in reaction rates residues often initiate overlaps during sequenator depending on the position of proline in the analysis. The cause has been shown to be an sequence, as demonstrated for the four prolines abnormally slow cleavage reaction. The kinetics in the JV-terminal section of the H2B histone from of the cleavage reaction has been studied and chicken, found to obey pseudo-first-order kinetics. There Abnormales Verhalten des Prolins im Isothiocyanat-AbbauZusammenfassung: Es wurde beobachtet, daß Bei den vier Prolinresten im N-terminalen AbProlinreste in der Sequenatoranalyse oft zu Über-schnitt des Hühner-H2B-Histons wurden je nach lappungen führen. Die Ursache dafür ist eine abPosition in der Sequenz beträchtliche Unternorm langsame Spaltungsreaktion. Für diese Reschiede der Reaktionsgeschwindigkeit beobachaktion wurde eine Kinetik pseudo-erster Ordtet. nung festgestellt.

Two of the four electrophoretic histone H2B variants present in wheat embryos have been isolated. The complete primary structure of the H2B,,, variant has been deduced from sets of overlapping peptides generated by CNBr cleavage, Staphyloccocus aureus V8 protease, endoproteinase Arg-C, the post-proline cleaving enzyme, chymotrypsin and cleavage in dilute acid. A minimum of 17 peptides were required to establish the sequence. This variant has a blocked N terminus and comprises a total of 149 amino acids. The C-terminal two-thirds of the protein are highly homologous to vertebrate H2B. In contrast, the N-terminal third is entirely different and contains an N-terminal extension of 23 residues in which the sequence Ala-Glu-Lys or variants are repeated several times. This region is also highly homologous to the H2B from Tetrahymenapyriformis. It shows in addition similarities to wheat H2A(1, and bovine H1.The primary structures of histones H3 and H4 in plants and animals are virtually identical. However, for the other histones even within the animal kingdom this structure conservation does not apply [l]. As to the histones from plants the knowledge of their primary structure is limited. Electrophoretic mobilities and chromatographic properties of wheat embryo histones suggested that histone H2B and H2A differ substantially from their animal counterparts [2 -51. This is confirmed by partial and complete amino acid sequences of H2A variants [2, 31 and the partial sequences of several H l variants [6]. A complete primary structure of a plant histone H2B has not yet been described. The amino acid composition of peptides of pea histone H2B [7] suggests a number of point mutations in the C-terminal region. We found that the N termini of histones H2B from wheat germ are blocked and that the chromatographic H2B fractions consisted of closely related variants. Peptide maps of wheat embryo histone H2B suggest that this fraction may contain closely related molecules [S]. We now report the complete primary structure of wheat histone H2B,,,. (EC 3.4.24.4); trypsin (EC 3.4.21.4); proline-specific endopeptidase (EC 3.4.21.26). MATERIALS AND METHODS Isolation _ _ _ _the deoxyribonucleoprotein with 0.2 M H2S04, followed by acetone precipitation.All the other experimental details are presented in the supplementary material at the end of this paper. Separation of peptides and nomenclatureExclusion chromatography and HPLC procedures used to purify the peptides are given in supplement Table 1 (where TFA = trifluoroacetic acid and HFBA = heptafluorobutycic acid). The nomenclature for the peptides was the following: E = endoproteinase Arg-C; CN = CNBr cleavage; SA = S. aureus protease; A = cleavage at Asp residues in dilute acid; CH = chymotrypsin; TH = thermolysin; P = post-proline cleavage enzyme; MT = maleylation followed by trypsin. Arabic numerals indicate the elution order of the peptides on size-exclusion and reverse-phase chromatography. A second numeral indicates that a HPLC fraction has been refractionated by HPLC under differen...