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Query: UNIPROT:P06889 (Mol)
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Histone H3 loci form a large multigene family in most plant species. In Glycine, some of these loci possess introns, whose sequences can provide characters for assessing phylogenetic relationships among species of the genus. Phylogenetic analyses of two closely related H3-B loci revealed a complex evolutionary pattern, producing trees from which species relationships could not be inferred readily. The single H3-D locus, in contrast, provided data suitable for the construction of gene trees whose topologies were sufficiently similar to other hypotheses of relationships within the subgenus Glycine to give confidence that evolution at this locus is tracking species phylogenies. H3-D topologies identified several of the same groupings found in previous phylogenetic studies using the chloroplast genome. However, histone H3-D and chloroplast genome data sets were in other respects incongruent, as revealed by both topological differences and numerical measures of congruence. The principal difference involved Glycine falcata, whose chloroplast genome belongs to one of the three strongly supported clades in the subgenus, but whose histone H3-D allele was sister to those of the remaining members of the subgenus. The H3-D topology is more in keeping with the morphologically, ecologically, and genetically divergent nature of this species. The H3-D locus appears to be a useful source of phylogenetic characters for interspecific studies in Glycine, providing resolution among taxa whose relationships were unresolved in previous studies.
Mol Phylogenet Evol 1996 Dec
PMID:Phylogenetic utility of histone H3 intron sequences in the perennial relatives of soybean (Glycine: Leguminosae). 897 98

Among the unicellular protists, several of which are parasitic, some of the most divergent eukaryotic species are found. The evolutionary distances between protists are so large that even slowly evolving proteins like histones are strongly divergent. In this study we isolated cDNA and genomic histone H3 and H4 clones from Trichomonas vaginalis. Two histone H3 and three histone H4 genes were detected on three genomic clones with one complete H3 and two complete H4 sequences. H3 and H4 genes were divergently transcribed with very short intergenic regions of only 194 bp, which contained T. vaginalis-specific as well as histone-specific putative promoter elements. Southern blot analysis showed that there may be several more histone gene pairs. The two complete histone H4 genes were different on the nucleotide level but encoded the same amino acid sequence. Comparison of the amino acid sequences of the T. vaginalis H3 and H4 histones with sequences from animals, fungi, and plants as well as other protists revealed a significant divergence not only from the sequences in multicellular organisms but especially from the sequences in other protists like Entamoeba histolytica, Trypanosoma cruzi, and Leishmania infantum.
J Mol Evol 1996 Dec
PMID:The sequence and organization of the core histone H3 and H4 genes in the early branching amitochondriate protist Trichomonas vaginalis. 899 53

The wheat bZIP protein HBP-1a(17) is a putative transcription factor regulating histone gene expression. To delineate the functional domain(s) of this factor, we made a series of effector constructs expressing fusion proteins, in which various portions of HBP-1a(17) are fused to the DNA-binding domain of the yeast transcriptional activator GAL4, in plant cells. When the beta-glucuronidase (GUS) reporter gene, driven by the wheat histone H3 core promoter harboring the GAL4-binding sequence, was co-transfected with such effector genes into tobacco protoplasts, several portions of HBP-1a(17) influenced reporter gene expression. The N-terminal one-third of HBP-1a(17), termed the P region (residues 1-118) due to its Pro content, did not activate the reporter gene, in contrast to the corresponding Pro-rich region of Arabidopsis GBF1 (residues 1-110), which functions as an activation domain. When the P region was divided into two, however, both its N-terminal (1-56; termed NP) and C-terminal (58-118; termed PC) halves were able to enhance expression of the reporter gene. When the NP region was further divided into NP(5-30) and NP(30-56), both regions still retained activating ability. These results suggest that the P region of HBP-1a(17) is composed of several modules each having activating function, and modification and/or conformational changes of the P region might influence its function.
Mol Gen Genet 1997 Feb 20
PMID:Dissection of the wheat transcription factor HBP-1a(17) reveals a modular structure for the activation domain. 906 88

The relative abundances of transcripts of different origins and housekeeping functions were measured by Northern blot analysis of RNA samples derived from in vitro-matured oocytes and in vitro-produced bovine embryos at selected stages of early development. The gene products studied included: two mitochondrial transcripts, 12S rRNA and cytochrome b mRNA; two RNAs involved in the processing of other RNAs, U2 and U3 snRNA; and two nuclear-derived transcripts, beta-actin mRNA and histone H3 mRNA. Overall, the RNA levels for the various genes studied remained constant or decreased slightly from the mature oocyte to the 6- to 8-cell or morula stage and were greatly increased in blastocysts. Differences were observed in the degree to which the RNA levels increased and in the timing of the increase. For 12S rRNA, a major increase was not observed until the blastocyst stage where levels increased 7.1 times the amount detected in morulae. Cytochrome b mRNA levels started to increase at the 6- to 8-cell stage and reached levels in blastocysts that were 20 times more than the cytochrome b mRNA level in 2- to 4-cell embryos. U2 snRNA levels did not increase until the blastocyst stage where levels were 6.4 times the amount found in morulae. U3 snRNA and beta-actin mRNA levels started to increase at the morula stage and blastocysts contained 118 and 110 times more U3 snRNA and beta-actin mRNA, respectively, than 6- to 8-cell embryos. However, blastocysts contained only two times the amount of histone H3 mRNA present in 6- to 8-cell embryos.
Mol Reprod Dev 1997 Aug
PMID:Changes in the relative abundance of various housekeeping gene transcripts in in vitro-produced early bovine embryos. 921 25

In the preimplantation mouse embryo, activation of the embryonic genome is accompanied by a transient enrichment of histone H4 acetylated at lysines 5, 8, and 12 at the nuclear periphery (Worrad et al., 1995: Development 121:2949-2959). In the present report, we use laser-scanning confocal microscopy and a new panel of antibodies to define the distribution of specific acetylated isoforms of the other three core histones in mouse embryos at the 1- to 4-cell stage. We find that histone H3 acetylated at lysine 9 and/or 18 (H3.Ac9/18) and the single acetylated form of H2A (H2A.Ac5) become transiently enriched at the nuclear periphery in the 2-cell embryo. In contrast, H3.Ac14, H3.Ac23, and acetylated H2B, like H4.Ac16, remain distributed throughout the nucleoplasm. The staining intensity with antisera to H3.Ac9/18, even at the periphery was weak compared to that obtained with antisera to acetylated H4. A brief period of culture, however, in the presence of the inhibitor of histone deacetylases trichostatin A (TSA) or trapoxin increased labeling. Thus, the steady-state level of H3.Ac9/18 at the nuclear periphery and H3.Ac14 and H3.Ac23 in the nuclear interior is relatively low, but turnover remains high. The localization of selected acetylated isoforms of H3 and H2A at the nuclear periphery was independent of ongoing transcription or of cytokinesis, but did require DNA replication. We propose a model in which the selective, replication-dependent acetylation and deacetylation of zygotic chromatin at the nuclear periphery mediates the programming of zygotic transcription.
Mol Reprod Dev 1997 Aug
PMID:Stage-dependent redistributions of acetylated histones in nuclei of the early preimplantation mouse embryo. 921 26

The Saccharomyces cerevisiae SWI/SNF complex is a 2-MDa multimeric assembly that facilitates transcriptional enhancement by antagonizing chromatin-mediated transcriptional repression. We show here that mutations in ADA2, ADA3, and GCN5, which are believed to encode subunits of a nuclear histone acetyltransferase complex, cause phenotypes strikingly similar to that of swi/snf mutants. ADA2, ADA3, and GCN5 are required for full expression of all SWI/SNF-dependent genes tested, including HO, SUC2, INO1, and Ty elements. Furthermore, mutations in the SIN1 gene, which encodes a nonhistone chromatin component, or mutations in histone H3 or H4 partially alleviate the transcriptional defects caused by ada/gcn5 or swi/snf mutations. We also find that ada2 swi1, ada3 swi1, and gcn5 swi1 double mutants are inviable and that mutations in SIN1 allow viability of these double mutants. We have partially purified three chromatographically distinct GCN5-dependent acetyltransferase activities, and we show that these enzymes can acetylate both histones and Sin1p. We propose a model in which the ADA/GCN5 and SWI/SNF complexes facilitate activator function by acting in concert to disrupt or modify chromatin structure.
Mol Cell Biol 1997 Nov
PMID:Role for ADA/GCN5 products in antagonizing chromatin-mediated transcriptional repression. 934 82

Although quantitatively minor replication-independent (replacement) histone variants have been found in a wide variety of organisms, their functions remain unknown. Like the H3.3 replacement variants of vertebrates, hv2, an H3 variant in the ciliated protozoan Tetrahymena thermophila, is synthesized and deposited in nuclei of nongrowing cells. Although hv2 is clearly an H3.3-like replacement variant by its expression, sequence analysis indicates that it evolved independently of the H3.3 variants of multicellular eukaryotes. This suggested that it is the constitutive synthesis, not the particular protein sequence, of these variants that is important in the function of H3 replacement variants. Here, we demonstrate that the gene (HHT3) encoding hv2 or either gene (HHT1 or HHT2) encoding the abundant major H3 can be completely knocked out in Tetrahymena. Surprisingly, when cells lacking hv2 are starved, a major histone H3 mRNA transcribed by the HHT2 gene, which is synthesized little, if at all, in wild-type nongrowing cells, is easily detectable. Both HHT2 and HHT3 knockout strains show no obvious defect during vegetative growth. In addition, a mutant with the double knockout of HHT1 and HHT3 is viable while the HHT2 HHT3 double-knockout mutant is not. These results argue strongly that cells require a constitutively expressed H3 gene but that the particular sequence being expressed is not critical.
Mol Cell Biol 1997 Nov
PMID:Constitutive expression, not a particular primary sequence, is the important feature of the H3 replacement variant hv2 in Tetrahymena thermophila. 934 91

While analysing the transcription of the cluster of cell-cycle regulated histone genes in Drosophila hydei, we have found transcripts spanned both histone H3 and H4 genes and were antisense for histone H3. As the two histone genes are in opposite orientation, these transcripts contained the sense strand of the histone H4 gene. Such transcripts were present in both poly(A)+ and poly(A)- RNA fractions. The polyadenylated molecules contained a poly(A) tail at the 3' end of the stem-loop structure, which is characteristic for cell-cycle regulated histone mRNAs. The antisense RNA of histone H3 is synthesized exclusively in testes. By developing an improved protocol of in situ hybridization to Drosophila testis squashes, we could demonstrate that the antisense transcripts are localized in the nuclei of primary spermatocytes. Possible functions of this RNA are discussed.
Mol Reprod Dev 1997 Dec
PMID:Naturally occurring testis-specific histone H3 antisense transcripts in Drosophila. 936 35

Sin mutations in Saccharomyces cerevisiae alleviate transcriptional defects that result from the inactivation of the yeast SWVI/SNF complex. We have investigated the structural and functional consequences for the nucleosome of Sin mutations in histone H3. We directly test the hypothesis that mutations in histone H3 leading to a SWI/SNF-independent (Sin) phenotype in yeast lead to nucleosomal destabilization. In certain instances this is shown to be true; however, nucleosomal destabilization does not always occur. Topoisomerase I-mediated relaxation of minichromosomes assembled with either mutant histone H3 or wild-type H3 together with histones H2A, H2B, and H4 indicates that DNA is constrained into nucleosomal structures containing either mutant or wild-type proteins. However, nucleosomes containing particular mutant H3 molecules (R116-H and T118-I) are more accessible to digestion by micrococcal nuclease and do not constrain DNA in a precise rotational position, as revealed by digestion with DNase I. This result establishes that Sin mutations in histone H3 located close to the dyad axis can destabilize histone-DNA contacts at the periphery of the nucleosome core. Other nucleosomes containing a distinct mutant H3 molecule (E105-K) associated with a Sin phenotype show very little change in nucleosome structure and stability compared to wild-type nucleosomes. Both mutant and wild-type nucleosomes continue to restrict the binding of either TATA-binding protein/transcription factor IIA (TFIIA) or the RNA polymerase III transcription machinery. Thus, different Sin mutations in histone H3 alter the stability of histone-DNA interactions to various extents in the nucleosome while maintaining the fundamental architecture of the nucleosome and contributing to a common Sin phenotype.
Mol Cell Biol 1997 Dec
PMID:Sin mutations of histone H3: influence on nucleosome core structure and function. 937 28

Amphiphilic lipopeptides, such as Pam3CysAlaGly and Pam3CysSerSer, were synthesized and incorporated into liposomes, and their ability to induce the proliferation of BALB/c mouse splenocyte was tested in vitro. When compared to monophosphoryl lipid A (MPL) the following potency order was found: liposomal lipopeptides > liposomal MPL > free (emulsified) lipopeptides. These results strongly depend on the size of the vesicles used: a mitogenic effect was observed only with lipopeptides incorporated within vesicles of diameter < or = 100 nm while lipopeptides in larger vesicles (diameter approximately 300 nm) gave no response. This may be related to the necessity for the liposome-associated lipopeptides to be endocytosed to reach putative intracellular targets. As immunoadjuvanticity seems to be linked to B-lymphocyte activation, the lipopeptides represent attractive alternatives to MPL for the realization of completely synthetic liposome-based peptide vaccine formulations. This was borne out by showing that Pam3CysAlaGly and Pam3CysSerSer, when incorporated in small unilamellar vesicles carrying a covalently conjugated synthetic peptide of sequence IRGERA, corresponding to an epitope of the C-terminal region of histone H3, were able to induce a potent and long-lasting immune response.
Mol Immunol 1997 Jun
PMID:Synthetic lipopeptides incorporated in liposomes: in vitro stimulation of the proliferation of murine splenocytes and in vivo induction of an immune response against a peptide antigen. 939 59


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