Nucleotide sequences of two corn histone H3 genes. Genomic organization of the corn histone H3 and H4 genes

Summary Two histone H3 genes have been cloned from a gtWES.B corn genomic library. The nucleotide sequences show 96% homology and both encode the same protein, which differs from its counterpart in wheat and pea by one amino acid substitution. The 5-flanking regions of the two corn H3 genes contain the classical histone-gene-specific consensus sequences and possess several regions of extensive nucleotide homology. A conserved octanucleotide 5-CGCGGATC-3 occurs at approximately 200 nucleotides upstream from the initiation ATG codon. This octanucleotide was found to exist in all of the 7 plant histone genes sequenced so far. Codon usage is characterized by a very high frequency of C (67%) and G (28%) at the third position of the codons, those ending by A (1%) and T (4%) being practically excluded.Comparison of Southern blots of EcoRI, EcoRV and BamHI digested genomic DNA suggests that the corn H3 and H4 genes are not closely associated. The H3 genes exist as 60 to 80 copies and the H4 genes as 100 to 120 copies per diploid genome. re]19851002 rv]19851212 ac]19851216     

H3 and H4 histone cDNA sequences from Xenopus: a sequence comparison of H4 genes

Ovarian poly (A) + RNA from Xenopus laevis and Xenopus borealis was used to construct two cDNA libraries which were screened for histone sequences. cDNA clones to H4 mRNA were obtained from both species and an H3 cDNA clone from Xenopus laevis. The complete DNA sequences of these clones have been determined and are presented. These new sequences are compared with other H3 and H4 DNA sequences both in the coding and 3' noncoding regions. We find that there is considerable non-random codon usage in ten H4 genes. In addition there are some sequence similarities in the 3' noncoding regions of H3 and H4 genes.     

d4 family genes: Genomic organization and expression

A family of closely related genes, named the d4 family, has been previously identified in mammals. It comprises three genes encoding structurally related proteins. The hallmark of the family is D4 domain—a double-paired finger motif that consists of two tandemly arranged PHD finger domains. These genes are expressed in various tissues and at various developmental stages. Two of those, neuro-d4 and cer-d4, are strictly neurospecific and their expression is developmentally regulated. Another gene, ubi-d4/Requiem is ubiquitously expressed in all embryonic and adult tissues at the same levels. d4 family genes are evolutionary conserved. Human, mouse, rat, and chicken d4 genes have been cloned. The only d4-like gene was found in the genome of nematode C. elegans and hydra H. magnipapillata. The sole member of d4 family was identified also in the genome of D. melanogaster. However, d4 genes are not believed to be present in the genomes of prokaryotes and yeast. This review describes genomic organization and expression of d4 family genes in vertebrates.     

Vertebrate histone genes: nucleotide sequence of a chicken H2A gene and regulatory flanking sequences.

The DNA sequence of a chicken genomal fragment containing a histone H2A gene has been determined. It contains extensive 5' and 3' flanking regions and encodes a protein identical in sequence to the histone H2A protein isolated from chicken erythrocytes. In the 5' flanking region, a possible "TATA box" and three possible "cap sites" can be recognised upstream from the initiation codon. To the 5' side of the "TATA box" is found an unusual sequence of 21 A's interrupted by a central G residue. It occupies the same relative position as the P. miliaris H2A gene-specific 5' dyad symmetry sequence and the "CCAAT box" seen in other eukaryotic polymerase II genes but is clearly different from both. A significant feature of the 3' non-coding region is the presence of a 23 base-pair sequence that is nearly identical to a conserved region found in sea urchin histone genes. The coding region is extremely GC rich, with strong selection for these bases in the third position of codons. Not a single coding triplet ends in U. No intervening sequences were found in this gene.     

Conserved organization of an avian histone gene cluster with inverted duplications of H3 and H4 genes

Summary The organization of histone gene clusters of the duckCairina moschata was studied in the DNA inserts of two recombinant phage that overlap and feature identical histone gene arrangements but differ in sequence details and in the extent of repetition of an AT-rich motif in one of the nontranscribed spacer regions. These few but substantial differences between otherwise nearly identical histone gene groups suggest that we have independently isolated alleles of the same site of the duck genome or that this gene arrangement occurs (with slight variations) more than once per haploid genome. Within the histone gene cluster described, H3 and H4 genes are duplicated (with inverted orientation), whereas one H1 gene is flanked by single H2A and H2B genes. The arrangement of duck histone genes described here is identical to a subsection of the chicken genome but differs from any other published histone gene cluster.     

Tetrahymena histone H3. Purification and two variant sequences

The H3 histone of the protozoan Tetrahymena pyriformis was obtained as described previously (Fusauchi, Y. & Iwai, K. (1983) J. Biochem. 93, 1487-1497) and further purified by Sephadex G-50 chromatography after reduction and carboxymethylation. The purified H3 was shown to comprise two variants, 75 mol% of H3(1) and 25 mol% of H3(2). The H3 mixture was directly sequenced by Edman degradation from the N-terminal through residue 104. Sequence determination was further performed with tryptic peptides and cyanogen bromide fragments derived from the H3 mixture. Thus, the total sequences of H3(1) and H3(2) were completely determined; both consist of a total of 135 amino acid residues (the molecular weights in the unmodified form are 15,336 for H3(1) and 15,424 for H3(2), and both are partially acetylated or methylated at the same six lysine residues to similar extents. The H3(1) and H3(2) sequences differ in 14 positions from each other, and in 17 and 21 positions from those of human spleen H3 (Ohe, Y. & Iwai, K. (1981) J. Biochem. 90, 1205-1211). The implications of these results for the structure-function relationship of this histone species and also for the phylogeny of protozoa are discussed.     

The two macronuclear histone H4 genes of the hypotrichous ciliate Stylonychia lemnae

Macronuclear DNA of hypotrichous ciliates is organized in short gene-sized molecules, each containing all regulatory sequences for autonomous replication and expression. In these organisms the histone genes are not clustered but dispersed on different molecules of various sizes. Two histone H4 genes containing fragments, one of 1.7 kb and one of 2.8 kb, were found in the macronucleus of Stylonychia lemnae. Restriction and sequence data reveal that the two genes-sized pieces are derived from different micronuclear precursors. Both histone H4 genes code for the same protein of 103 aminoacids but differ greatly in their 5'-and 3'-regions.     

Isolation and characterization of two human H1 histone genes within clusters of core histone genes

Two human H1 histone genes, termed H1.3 and H1.4, were isolated from two cosmid clones. The H1.4 gene is associated with an H2B gene, whereas genes coding for all four core histones are located in the vicinity of the H1.3 gene. This cluster arrangement was found both in the two cosmid clones and on overlapping bacteriophage clones isolated from an EMBL3 library. In continuation of our previous analysis of two human H1 genes, this analysis raises the number of completely sequenced H1 histone genes within clusters of core histone genes to four.     

The nucleotide sequences of two leghemoglobin genes from soybean.

We present the complete nucleotide sequences of two leghemoglobin genes isolated from soybean DNA. Both genes contain three intervening sequences in identical positions. Comparison of the coding sequences with known amino-acid sequences of soybean leghemoglobins suggest that the two genes correspond to leghemoglobin C2 and leghemoglobin C3, respectively.     

The nucleotide sequences of two tRNAAsn genes from tobacco chloroplasts

Recombinant plasmids which contain EcoRI fragments of tobacco chloroplast DNA carrying tRNA genes were constructed. Plasmids pTC211 and pTC293 contain the base sequences for tRNAAsn in their 1.4 and 1.1 Md EcoRI fragments, respectively. These two tRNA sequences are identical and are; 5'-TCCTCAGTAGCTCAGTGGTAGAGCGGTCGGCTGTTAACCGATTGGTCGTAGGTTCGAATCCTACTTGGGGAG-3'. Each tRNAAsn gene is located at about 0.9 kb apart from the distal end of each 5S rRNA gene and is coded for by the DNA strand opposite from that of the rRNA genes.