Occurrence of H1o-like protein and protein A24 in the chromatin of bullfrog erythrocytes lacking histone 5

Distribution of sulphydryl groups and disulphide linkages in tissue proteins of quail uropygial glands

1. The distribution of sulphydryl (-SH) groups and disulphide (S-S) linkages in the tissue proteins of quail uropygial glands was histochemically observed by a staining method using N-[7-dimethylamino-4-methyl-3-coumarinyl]maleimide. 2. In the uropygial gland, the -SH groups of the tissue proteins of glandular cells displayed a progressive change to S-S linkages concomitant with the shift from the transitional cell layer to the degenerating cell layer, suggesting that cell destruction was occurring with the products being released as secretions. This phenomenon was apparently more pronounced in the deep compared with the shallow portion of secretory tubules. 3. The above results indicated that a mechanism similar to epidermal differentiation operates in the process of holocrine secretion in the uropygial gland.

Immunochemical studies of histone H5 from Halobatrachus didactylus

1. Histone H5 from Halobatrachus didactylus was isolated by using perchloric acid (PCA) extraction of fish liver nuclei and trichloroacetic acid (TCA) precipitation. 2. A polyclonal antiserum was generated by immunizing rabbits with the antigen purified from SDS-PAGE. 3. By immunofluorescence the serum stains erythrocyte nuclei from H. didactylus but it does not react with mammalian cells. 4. By Western blotting, the anti-H5 antibody reacts with the isolated antigen at high titers. 5. Digestion of histone H5 with pepsin and cyanogen bromide suggests that the epitopes are located in the globular and C-terminal region of the H5 molecule excluding the N-terminal.

The occurrence and properties of histone H1 zero in quiescent rabbit tissues

1. The issue of the existence and the properties of histone H1 zero in quiescent rabbit tissues was approached by electrophoretic, chromatographic and immunochemical techniques. 2. The results demonstrated that the rabbit tissues did contain a typical histone H1 zero, its properties being comparable to those of H1 zero from all other sources studied thus far.

Conserved epitopes on plant H1 histones recognized by monoclonal antibodies

A series of monoclonal antibodies specific for distinct regions of H1 histone from the plant Nicotiana tabacum were obtained from fusion experiments with spleen cells of mice immunized with tobacco nuclear extracts. These monoclonal antibodies were characterized and the evolutionary conservation of the epitopes in higher plants and animals studied by immunoblotting and enzyme-linked immunosorbent assay (ELISA). Whereas some epitopes appear restricted to the Solanaceae plant family, others are common to all higher eukaryotes tested and even detectable on nuclear proteins of yeast. ELISA experiments performed with isolated tobacco chromatin give some indications of the differential accessibility of the epitopes after interaction of H1 histone with the nucleosome.

Isolation and expression of cDNA clones coding for two sequence variants of Xenopus laevis histone H5

We have cloned and characterized cDNAs coding for two variants of Xenopus laevis H5 histone protein (previously called H1s). cDNA was synthesized from RNA of immature erythrocytes in a single reaction using a modification of the method of Gubler and Hoffman [Gene 25 (1983) 263-269], and blunt-end ligated into the HincII site of the phage vector M13mp9. Immunological screening with a polyclonal antibody yielded two clones expressing H5 peptide. Sequence characterization revealed that both clones contained partial cDNA inserts and that the smaller 340-bp clone initiated reverse transcription within the coding region, at a site rich in adenine. Rescreening of the cDNA bank by nucleic acid hybridization produced eleven additional H5 clones, one of which coded for a second variant of H5. These two variants, called XLH5A and XLH5B, are very similar in sequence and code for proteins of 195 and 193 amino acids, respectively, which may be the H1D and H1E variants observed previously. XLH5, avian H5 and human H1O share identity at both nucleotide and amino-acid sequence levels. Further, the XLH5-coding mRNA is likely polyadenylated and lacks the highly conserved, 23-nucleotide dyad symmetry element found within the 3' untranslated regions of most histone-coding mRNAs.

Predictability of sequence homologies among lysine-rich histones by immunological distance

The relationship between immunological distance (I.D.) measured by microcomplement fixation and amino acid sequence difference for lysine-rich histones was tested using antisera to lysine-rich histones of known sequence, chicken H1 and H5, goose H5, and trout H1 as well as to trout H5. The best relationship between I.D. (y) and percent sequence difference (x) for lysine-rich histones, y = 2x, applies as well to other histones of known sequence but it differs from y = 5x, reported for other proteins and often used for histones. Although deviations indicate that I.D. is a poor predictor of primary sequence differences among histones, it suggests that trout H5 is more closely related to H1 than to chicken H5.

Preparation of chromosomal protein A24 (uH2A) by denaturing gel filtration and preparation of its free nonhistone component ubiquitin by ion-exchange chromatography

Chromosomal protein A24 (uH2A) is unique in that it comprises the nucleosomal core histone H2A in isopeptide linkage with the highly conserved, globular, and stable nonhistone protein ubiquitin. Some 10% of the chromatin complement of H2A is modified in this way and studies to elucidate a role for this modification have concentrated on observations requiring no purification of A24 due to the difficulty in isolating the protein in large and pure quantities. We describe a method for isolating A24 by chromatography on Pharmacia G-100 gel filtration medium under urea denaturing conditions. A24 prepared by this method is structurally intact and is available in the quantities required for studies of the behavior and influence of the protein on histone-histone, histone-DNA, and enzymatic interactions. In conjunction with this method we describe a procedure for the isolation of large quantities of free ubiquitin of far greater purity than previously reported.

Presence of a H1o-type histone in an invertebrate--the bivalve mollusc Anodonta cygnea

Some terminally differentiated tissues of the bivalve mollusc Anodonta cygnea contain a histone subfraction with electrophoretic and immunological characteristics similar to those of the mammalian histone H1o.

Uncoupled synthesis of H1o-like histone H1s during late erythropoiesis in Xenopus laevis

This study investigated the synthesis of Xenopus histones during erythropoiesis. Although cessation of DNA replication in the mid-stages of erythroid maturation is accompanied by arrested synthesis of histone H1 and core histones, synthesis of H1o (an H1o-like histone) was found to continue into late stages of erythropoiesis, as has been reported for avian erythrocyte histone H5. This was accompanied by a threefold increase in the relative amount of Xenopus H1s, similar to the accumulation reported for H5 during avian erythropoiesis and for H1o in some differentiated mammalian cells. The structural and metabolic homologies of avian H5, mammalian H1o, and Xenopus H1s imply that these lysine-rich histones have closely related functions distinct from those of H1, and thus represent a subclass of lysine-rich histones.

New findings on the proteins of sebaceous glands

In order to understand the distribution and concentration of proteins with -SH groups or S-S linkages in sebaceous cells during differentiation and holocrine secretion of sebaceous glands, skin specimens from the inner side of ears of New Zealand white rabbits were examined histochemically and ultrastructurally. DACM (N-[7-dimethylamino-4-methyl-3-coumarinyl] maleimide) staining method showed that proteins containing -SH groups were present in the cells (cytoplasm and nuclei) in all layers from the peripheral to the terminally differentiated cells of sebaceous glands and that proteins containing S-S linkages were present in the terminally differentiated cells and their pyknotic nuclei but not in the peripheral and differentiating cells of sebaceous glands. Lipid droplets in all sebaceous cells contained neither -SH groups nor S-S linkages. Ultrastructurally, the terminally differentiated cells were very electron dense and seemed to be abruptly formed from the differentiating cells that were producing lipid droplets. These findings indicate that the conversion of -SH groups to S-S linkages of proteins also occurs in sebaceous glands as in epidermis and hair.

Presence of histone H1o-related fraction in chicken liver

The lysine-rich histones of chicken liver were studied in order to see whether a protein similar to mammalian histone H1o was present in this lower vertebrate. The following biochemical methods were used: sodium dodecylsulphate and acid-urea electrophoresis, gel exclusion chromatography on BioGel P100, and ion-exchange chromatography on BioRex 70. Specific polyclonal antibodies were elicited against purified mouse liver H1o and chicken erythrocyte H5, and applied for the further characterization of the chicken H1 subfractions obtained chromatographically. The results from microcomplement fixation and enzyme-linked immunosorbent assays showed that the presumptive chicken liver H1o shared common antigenic determinants with the mammalian H1o and the chicken liver H5. Based on the combined biochemical and immunological evidence, we conclude that an H1o-like protein is present in quiescent differentiated avian cells. The data of Smith et al. [34], who did not find this specific lysine-rich histone in resting chicken cells, are discussed.

Antibody against globular domain of H10 histone

Antibodies against the globular domain of histones H10 and H5 were developed in rabbit. The antibody against the globular domain of H5 cross-reacted with H10 but not with H1; the antibody against the globular domain of H10 did not cross-react with H5, H1 or with HMG proteins. The globular domain of H10 therefore appears to have an immunological determinant(s) which does not exist in H1 and H5. By use of these antibodies, we show that nucleated erythrocytes of bullfrog contain an H10-like protein (not an H5-like protein). This observation coincided with the report of Shimada, T. et al. [J. Biol. Chem. 256 (1981) 10577-10582]. These antibodies have application in detecting H10-like proteins in eukaryotic cells.

Occurrence of histone H10-related protein fraction in trout liver

The lysine-rich histones of trout liver were studied in order to see whether a protein similar to mammalian histone H1(0) exists in this lower vertebrate. The biochemical methods used involved SDS and acid-urea polyacrylamide gel electrophoresis, gel exclusion and ion-exchange chromatography. Specific rabbit antibodies were elicited against chromatographically-purified mouse liver H1(0) and applied for further characterization of the presumptive trout-liver H1(0) fraction. The results from the indirect immunofluorescence on nitrocellulose-immobilized crude H1 subfractions and from the complement fixation test supplied additional evidence for the existence of an H1(0)-like protein in trout liver.

Developmental changes in non-histone chromosomal proteins of bullfrog (Rana catesbeiana)

1. Chromatins were isolated from liver, brain, kidney, spleen, heart muscle and erythrocytes of the bullfrog and its tadpole, Rana catesbeiana and their non-histone chromosomal proteins (NHC proteins) were compared by a simple electrophoretic method. 2. No qualitative but quantitative variations in the composition of NHC proteins were found among the tissues examine. 3. The tissue of tadpole and frog were classified into three groups according to their electrophoretic pattern of NHC proteins' brain, heart muscle and spleen showing almost the same pattern, liver and kidney showing different pattern in some components, and erythrocytes showing markedly different pattern. 4. Component D3 occurring i the frog liver, not in the tadpole, was found to increase in the tadpole liver during natural and thyroxine-induced metamorphosis.