PubMed Health⌕ Search

Biomedical subjects

M Iwabuchi

Publications and source records attributed to M Iwabuchi.

At least 91 records · Page 5Linked to original sources
PubMed1992

Phenol-treatment and a homologous pairing-assay.

Homologous pairing is a key step in homologous genetic recombination. In the early stage of trials for the identification of homologous pairing-promoting proteins from a fission yeast, Schizosaccharomyces pombe, we treated DNA products with phenol in the presence of a salt for the removal of tightly bound proteins from DNA before the assay, but we found that this treatment caused very efficient protein-independent double-strand formation from complementary single-stranded DNAs. Using an assay including the phenol treatment, we detected another species of apparent homologous pairing-promoting proteins in the nuclei, in addition to a homologous pairing-promoting protein consisting of three components which we reported previously. However, studies involving the use of an assay without the phenol-treatments revealed that the second one was not really a homologous pairing-protein. Thus, the protein-independent double-strand formation by phenol-treatment in the presence of a salt could cause the erroneous identification of homologous pairing-promoting proteins.

Bacteriophages↗
PubMed1992

Highly conserved hexamer, octamer and nonamer motifs are positive cis-regulatory elements of the wheat histone H3 gene.

Base substitution mutations were introduced into the promoter region of the wheat histone H3 gene, and promoter activity was assayed in stably transformed sunflower calli or in wheat protoplasts transfected transiently. At least four positive regulatory elements, a hexamer motif (ACGTCA), two octamer(-like) motifs of a direct (CcCGGATC) and a reverse (aATCCGCG) form, and a nonamer motif (CATCCAACG) were identified within the -185 region of the H3 promoter. Analyses of the type I element (CCACGTCACCaATCCGCG) consisting of the hexamer and reverse-oriented octamer motifs, and which is conserved in other plant histone genes as well, predicted the presence of an octamer-binding protein(s).

Base Sequence↗
PubMed1992

Isolation and characterization of a cDNA clone encoding the TATA box-binding protein (TFIID) from wheat.

We isolated a complementary DNA (cDNA) encoding the TATA-binding factor 'TFIID' from a wheat seedling cDNA library. The wheat TFIID transcript of 1.2 kb poly(A)+ RNA was expressed at a low level early in germination, but gradually increased as the seedlings developed. In vitro binding experiments showed that the bacterially expressed wheat TFIID protein could specifically bind to the TATA boxes of the cauliflower mosaic virus (CaMV) 35S, wheat histone H3 and adenovirus major late genes with different affinity. A comparison with Arabidopsis TFIID showed the presence of a plant-specific region consisting of 13 amino acids at the divergent amino terminus and a conserved region (182 amino acids) at the carboxy terminus longer than that observed in yeasts (180 amino acids) and animals (181 amino acids).

Amino Acid Sequence↗
PubMed1991

Sequence-specific single-strand DNA-binding proteins that interact with the regulatory regions of wheat histone H3 and H4 genes.

We identified two novel DNA-binding proteins, ssDBP-1 and ssDBP-2, in wheat germ nuclear extract that interact with the proximal sequences of the promoter regions of the wheat histone H3 and H4 genes. Mobility shift and methylation interference assays have demonstrated that these factors specifically bind to the single-strand DNA which partially overlaps the hexamer and octamer cis-elements of the H3 promoter. Both proteins are distinguishable from HBP-1a and HBP-1b which specifically bind to the H3 hexamer sequence. These ssDNA-binding proteins are supposed to regulate the transcription of the wheat histone genes.

Base Sequence↗
PubMed1991

HBP-1a and HBP-1b: leucine zipper-type transcription factors of wheat.

Wheat transcription factors HBP-1a and HBP-1b bind to the hexamer motif, ACGTCA, of wheat histone gene promoters. HBP-1b also binds to the hexamer motif in the promoter of the 35S RNA gene of cauliflower mosaic virus, whereas HBP-1a does not. A cDNA clone encoding HBP-1b was isolated on the basis of its binding specificity to the hexamer motif. The deduced amino acid sequence indicates that HBP-1b, like HBP-1a, belongs to a leucine zipper class of transcription factors. Mutational analyses of the HBP-1a and -1b encoded cDNAs revealed that truncated polypeptides containing the leucine zipper and basic regions are sufficient for DNA binding. HBP-1a and -1b form homodimers, as expected from earlier studies on this class of transcription factors, but did not form heterodimers. Although the hexamer motif or its homologs exist in several plant genes, HBP-1a and -1b exhibited the highest binding affinity to the hexamer motif in the histone promoters, suggesting that both DNA binding proteins are involved in transcriptional regulation of wheat histone genes.

Amino Acid Sequence↗
PubMed1990

Cell cycle-regulated gene expression in transgenic plant cells.

A majority of histone genes are expressed in the S phase during the cell cycle. Using the gene expression system of transformed sunflower cells into which wheat histone H3 gene was introduced by the Ti-plasmid gene transfer technique, we determined three cis-acting control sequences (hexameric, octameric, and nonameric motifs) which seemed to confer the S-phase-specific transcription of wheat histone genes. Furthermore, as candidates for regulatory transcription factors, three nuclear DNA-binding proteins HBP-1a, HBP-1b, and HBP-2 that interact with the hexameric and nonameric motifs were identified. The structural analysis of the cDNA of HBP-1a revealed that a nuclear protein has the leucine-zipper structure and a DNA-binding motif. The hexameric motif in the H3 gene was also seen in cauliflower mosaic virus 35S (CaMV 35S) promoter and shown to function as a regulatory element of this promoter. The wheat HBP-1b can interact with the hexameric motif of the CaMV 35S promoter. Much attention has been paid to the significance of the hexameric sequences within the H3 and CaMV 35S promoters and the DNA-binding proteins HBP-1a and HBP-1b.

Base Sequence↗
PubMed1990

Isolation and characterization of spore coat protein (sp96) gene of Dictyostelium discoideum.

A cDNA library was constructed from poly(A)+ RNA isolated from slug cells of Dictyostelium discoideum, using lambda gt11 phage, and screened with an antiserum specific for the spore coat protein sp96. A positive clone was obtained and the gene product was identified as sp96. The sp96 mRNA is 2.2 kb in size, and it starts to accumulate at the tipped aggregate stage only in prespore cells. Southern analysis using nuclear DNA established that the sp96 gene is unique. Two genomic clones containing the sp96 gene were isolated and the sequence of the gene established. The coding region contains a long open reading frame interrupted by a single intron.

Amino Acid Sequence↗
PubMed1989

Wheat nuclear protein HBP-1 binds to the hexameric sequence in the promoter of various plant genes.

HBP-1 is a sequence-specific DNA-binding protein that interacts with the hexameric sequence ACGTCA, the putative cis-acting element of the wheat histone H3 gene. Gel mobility shift and DNase I footprint analyses showed that this protein interacts with homologous sequences in the regulatory regions for the transcription of the cauliflower mosaic virus (CaMV) 35S RNA and nopaline synthase (NOS) genes, evidence that HBP-1 may bind to hexameric sequences in the regulatory regions of various genes. An HBP-1-like protein, indistinguishable from wheat HBP-1 in its the DNA-binding specificity, is present in sunflower nuclear extract, an indication that HBP-1-like DNA-binding proteins also exist in dicots.

Amino Acid Oxidoreductases↗
PubMed1989

Function of the hexameric sequence in the cauliflower mosaic virus 35S RNA promoter region.

The hexameric sequence ACGTCA functions in transcriptional regulation of wheat histone genes. The cauliflower mosaic virus (CaMV) 35S RNA promoter has the same hexameric sequence, and mutation analyses confirmed that the hexamer contributed greatly to transcription from the 35S promoter when a test gene with this promoter was introduced into sunflower cells. Electrophoretic mobility shift assays revealed the existence of a nuclear protein(s) in sunflower cells which is homologous to the HBP-1b that has been identified as binding to the 35S promoter in wheat. These results provide evidence of the involvement of the hexameric sequence and the HBP-1b-like DNA binding protein(s) in transcription from the 35S promoter.

Base Sequence↗
PubMed1989

Multiplicity of the DNA-binding protein HBP-1 specific to the conserved hexameric sequence ACGTCA in various plant gene promoters.

A novel DNA-binding protein that specifically interacts with the hexameric sequence ACGTCA in the regulatory region of the wheat histone H3 gene has been identified in wheat nuclear extract and designated HBP-1a. The nuclear protein HBP-1 previously identified as a DNA-binding protein that interacts with hexameric sequences in the H3, cauliflower mosaic virus (CaMV) 35 S RNA, and nopaline synthase (NOS) promoter regions therefore has been renamed HBP-1b. The flanking sequences that surround the hexameric sequence may account for the difference in the binding properties of HBP-1a and HBP-1b.

Binding, Competitive↗
PubMed1989

A protein that binds to a cis-acting element of wheat histone genes has a leucine zipper motif.

The structure and function of transcription factors of higher plants was studied by isolating cDNA clones encoding a wheat sequence-specific DNA binding protein. A hexameric nucleotide motif, ACGTCA, is located upstream from the TATA box of several plant histone genes. It has been suggested that this motif is essential for efficient transcription of the wheat histone H3 gene. A wheat nuclear protein, HBP-1 (histone DNA binding protein-1), which specifically binds to the hexameric motif, has previously been identified as a putative transcription factor. A cDNA clone encoding HBP-1 has been isolated on the basis of specific binding of HBP-1 to the hexameric motif. The deduced amino acid sequence indicates that HBP-1 contains the leucine zipper motif, which represents a characteristic property of several eukaryotic transcription factors.

Amino Acid Sequence↗
PubMed1989

Four tandem defective P elements associated with positive regulation of the Drosophila melanogaster glucose-6-phosphate dehydrogenase gene.

Three high-glucose-6-phosphate dehydrogenase (G6PD)-activity mutants (2512H, S44H, and 1FH) are characterized by two insertion sequences associated with the G6PD locus; one (Ins1; 3.5 kb long in 2512H and S44H and 2.9 kb long in 1FH) is present just 5' to exon I and consists of a KP' (the 32nd base of the KP was replaced by guanine), a core sequence and a KP, and the other is 4.2 kb long and resides within an intron. Southern blot analyses of revertants showing low G6PD activity suggested that the insertion sequence responsible for high G6PD activity may be the core sequence but not the flanking KP and KP' or the Ins2. DNA sequencing data of the clone carrying the core sequence of 2512H demonstrated that the core sequence is another type of defective P elements (core P). Interestingly, a protein(s) was found in the nuclear extract of Canton S embryos that specifically binds to the core P but not to the KP or various fragments of p pi 25.1. In addition, the mutant G6PD activity was found to be affected not only by the genotype, but also by cytoplasmic factors.

Animals↗
PubMed1988

DNA-binding protein(s) interacts with a conserved nonameric sequence in the upstream regions of wheat histone genes.

A nuclear protein(s), HBP-2, that binds to the upstream region of the wheat histone H4 gene was identified from a fractionated nuclear extract of wheat germ by DNase I footprinting. The DNase I-protected region contained the conserved nonameric motif, CATCCAACG. Cross-competition experiments that used the mobility shift assay showed that this nuclear protein(s) binds specifically to the upstream sequence that has been postulated to be a cis element of the wheat H3 gene. Our findings suggest that this DNA-binding protein(s) may be a trans-acting factor in the regulation of the transcription of wheat histone genes.

Base Sequence↗