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H Yamagata

Publications and source records attributed to H Yamagata.

At least 19 recordsLinked to original sources
PubMed1997

Phytochrome-regulated repression of gene expression requires calcium and cGMP.

The plant photoreceptor phytochrome A utilizes three signal transduction pathways, dependent upon calcium and/or cGMP, to activate genes in the light. In this report, we have studied the phytochrome A regulation of a gene that is down-regulated by light, asparagine synthetase (AS1). We show that AS1 is expressed in the dark and repressed in the light. Repression of AS1 in the light is likely controlled by the same calcium/cGMP-dependent pathway that is used to activate other light responses. The use of the same signal transduction pathway for both activating and repressing different responses provides an interesting mechanism for phytochrome action. Using complementary loss- and gain-of-function experiments we have identified a 17 bp cis-element within the AS1 promoter that is both necessary and sufficient for this regulation. This sequence is likely to be the target for a highly conserved phytochrome-generated repressor whose activity is regulated by both calcium and cGMP.

Aspartate-Ammonia Ligase↗
PubMed1997

Cloning and analysis of a cDNA encoding a two-domain hemoglobin chain from the water flea Daphnia magna.

A cDNA encoding a two-domain hemoglobin (Hb) chain of Daphnia magna was cloned and its nucleotide (nt) sequence of 1261 bp was determined. The nt sequence contained 74 bp of the leader sequence, 1047 bp of an open reading frame (ORF), and 119 bp of the 3'-untranslated region (UTR), excluding the polyadenylation tail. A sequence, AATACA, located 24 bp upstream from the polyA sequence was considered to be a polyadenylation signal. cDNA-derived amino acid (aa) sequence revealed that D. magna Hb chain is synthesized as a secretory precursor with a signal peptide of 18 aa. Mature D. magna Hb chain consists of 330-aa residues with a calculated molecular weight of 36227, which is composed of two large repeated domains, domain 1 and 2. Several key aa that are invariant in all or most of other Hb and required for functional heme-binding are conserved in each of the two domains. The N-terminal extension (pre-A segment) of domain 1 was unusually long and contained an unusual threonine-rich sequence. The homology between the aa sequences of the two domains (24% identity) was much lower than that observed in other two-domain Hb chains from clams or nematode. Hb mRNA level in D. magna reared under low oxygen concentration was more than 12 times higher than that in D. magna reared with sufficient aeration, indicating that the expression of Hb gene is regulated by mRNA level.

Amino Acid Sequence↗
PubMed1997

Cloning of dnaK and dnaJ homologous genes from a purple non-sulfur bacterium Rhodopseudomonas species.

The dnaK and dnaJ genes were isolated as a cluster from a purple non-sulfur phototrophic bacterium, Rhodopseudomonas species No. 7 by a polymerase chain reaction (PCR) based method. The deduced products of dnaK (631 amino acids) and dnaJ (379 amino acids) were 67% and 56% identical to the respective Escherichia coli gene products. The functions of DnaK and DnaJ could be confirmed by complementation of the respective E. coli mutants.

Amino Acid Sequence↗
PubMed1997

Haplotype analysis of congenital myotonic dystrophy patients from asymptomatic DM father.

We report a family with congenital myotonic dystrophy (CDM) transmitted from an asymptomatic DM father; we analyzed the haplotype of this family by using polymorphism within and by flanking the DM protein kinase locus. One patient with congenital DM was homozygous for all markers studied, except for the expanded CTG repeats. Two other patients with congenital DM were heterozygous. One patient with congenital DM who was homozygous had greater clinical severity and more expanded CTG repeats than other CDM patients who were heterozygous. The asymptomatic father had a DM protomutation.

Child↗
PubMed1997

Structural and functional analysis of the phosphoenolpyruvate carboxylase gene from the purple nonsulfur bacterium Rhodopseudomonas palustris No. 7.

The ppc gene, encoding phosphoenolpyruvate carboxylase (PEPC), from Rhodopseudomonas palustris No. 7 was cloned and sequenced. Primer extension analysis identified a transcriptional start site 42 bp upstream of the ppc initiation codon. An R. palustris No. 7 PEPC-deficient strain showed a slower doubling time compared with the wild-type strain either anaerobically in the light or aerobically in the dark, when pyruvate was used as a carbon source.

Amino Acid Sequence↗
PubMed1996

The efficient production of human epidermal growth factor by Bacillus brevis.

A system has been developed for the efficient production of heterologous proteins using Bacillus brevis as a host that secretes large amounts of cell wall protein into the medium. The promoter region and signal peptide-encoding region of the cell wall protein gene were used to construct an expression-secretion vector. Bacterial proteins such as amylases can be produced in large amounts by this system (1 g/l or more), but mammalian proteins such as human alpha-amylase are produced at a low level (one or two orders of magnitude less than for bacterial proteins). The highly efficient secretion of human epidermal growth factor (h-EGF, more than 1 g/l) was obtained with B. brevis HPD31 as the host and plasmid pHY481, derived from B. brevis 481, as the vector. Recombinant hEGF was purified easily from the culture supernatant by two steps. Purified hEGF had the identical NH2-terminal amino acid sequence and COOH-terminal amino acid sequence with those of the authentic hEGF, and it was fully active in biological assays. This recombinant hEGF has been shown to be successful for biological wool harvesting (CSIRO, Australia). These results, in combination with previous results, indicate that foreign proteins of diverse origins can be produced efficiently as functional proteins in B. brevis.

Amino Acid Sequence↗
PubMed1996

Heterologous expression and site-directed mutagenesis studies on the activation mechanism and the roles of the basic residues in the prosegment of aspergillopepsinogen I.

To study the structure/function relationship of the prosegment of aspartic proteinase, a putative proform of aspergillopepsin I (or proteinase B) from Aspergillus niger var. macrosporus was expressed by Escherichia coli, refolded in vitro, and purified. The conversion of the purified proenzyme (aspergillopepsinogen I, proproteinase B) into the active mature form occurred at pH < or = 4.5 and was completely inhibited by pepstatin A, a specific inhibitor for aspartic proteinase, suggesting autoprocessing. The N-terminus of this mature form was Glu67 (numbering in preproform), which was different from the N-terminal Ser70 of native proteinase B although there was no significant difference in enzymatic activity. During the conversion, two intermediates were observed on SDS/PAGE, indicating a stepwise mechanism. The Lys56-Phe57 sequence seems to be a counterpart of the Lys-Tyr pair highly conserved in the prosequences of aspartic proteinases. When the mutant proenzyme (K56N), in which Lys56 was replaced with Asn by site-directed mutagenesis, was allowed to refold under various conditions, no significant potential activity could be obtained. Proproteinase B was also expressed by Bacillus brevis HPD31. This system required no in vitro refolding to obtain potentially active proenzyme, which was secreted into the culture medium (30-120 mg/l) and had the same properties with that obtained by the E. coli system. The K56N mutant prepared by this system also had no potential activity, and was rapidly digested by incubation with native proteinase B, suggesting that the mutant did not fold correctly. On the other hand, the K56R mutant (Lys56-Arg) was potentially active. These results indicated that Lys56 is essential for the folding through electrostatic interaction with the catalytic Asp residues in the active site although it may be replaced with Arg. In the presence of a low concentration of pepstatin A, an incompletely processed form with N-terminal Ser53 was obtained. Further, the R52Q (Arg52-->Glin) mutant showed no processing but was converted to the active mature form by incubation with the native enzyme. Therefore, the cleavage between Arg52 and Ser53 is considered to be the initial and essential step of the autoactivation. The R26Q, K27Q, R36Q, K40Q, R42Q, and K66Q mutants were also potentially active. The K66Q mutant was processed to a form with N-terminal Ala55.

Amino Acid Sequence↗
PubMed1996

Association of CTG repeats and the 1-kb Alu insertion/deletion polymorphism at the myotonin protein kinase gene in the Japanese population suggests a common Eurasian origin of the myotonic dystrophy mutation.

We have studied linkage disequilibrium between CTG repeats and an Alu insertion/deletion polymorphism at the myotonin protein kinase gene (DMPK) in 102 Japanese families, of which 93 were affected with myotonic dystrophy (DM). All of the affected chromosomes are in complete linkage disequilibrium with the Alu insertion allele. Among the normal chromosomes, alleles of CTG repeats 5 and > or = 17 are exclusively associated with the insertion allele. On the other hand, intermediate alleles of 11-16 repeats show a significantly greater association with the deletion allele. A strikingly similar pattern of linkage disequilibrium observed in European populations suggests a common origin of the DM mutation in the Japanese and European populations.

Asian People↗
PubMed1996

Late development of anti-La/SS-B antibodies in a patient with Sjogren's syndrome and high titer anti-Ro/SS-A antibodies.

The frequent coexistence of anti-Ro and anti-La autoantibodies is well described, however, there is little evidence of sequential development of these two autoantibodies. We report a case of typical Sjogren's syndrome with high titer anti-Ro antibodies, who subsequently developed anti-La antibodies later in the course. This case suggests that the anti-La antibodies may actually follow the anti-Ro antibodies in some cases as hypothesized in the concept of linked set of autoantibodies, analogous to development of anti-Sm in certain anti-nRNP antibody positive SLE patients and animal models.

Antibodies, Antinuclear↗
PubMed1996

Restricted heterogeneity and changing spectrotypes in autoantibodies to La/SS-B.

Isoelectric focusing (IEF) spectrotype of specific immunoglobulins has been studied as a marker for B-cell clonality. In the present study, the spectrotype of anti-La antibodies in human autoimmune sera were analyzed by newly developed IEF sandwich assay in which focused total immunoglobulin on filter papers are incubated with crude antigen followed by horse-radish peroxidase-labeled anti-La antibodies. The anti-La spectrotypes contained oligoclonal bands, the positions and patterns of which are different in each patient, suggesting the preferential expansion of limited numbers of anti-La producing B-cell clones unique to individual patients. Furthermore, the bands on anti-La spectrotype in sequentially obtained sera changed continuously, suggesting alteration in the expanding anti-La producing clones. These may reflect affinity maturation and/or diversification of the B-cell epitopes involving somatic mutation.

Antibodies, Antinuclear↗
PubMed1996

An intergenerational contraction of the CTG repeat in Japanese myotonic dystrophy.

We present the first report of a Japanese family with myotonic dystrophy (DM) that showed an intergenerational contraction of the CTG repeat. The size of the expanded CTG repeats was 3.2 kb for the father and 2.2 kb for the daughter, indicating that the expansion decreased during transmission from the father to the daughter. Despite the CTG repeat contraction, the daughter showed earlier age of onset than the father. However, she appeared to be less severely affected than the father. We discuss the correlation between the CTG repeat contraction and the clinical phenotype. The presence of the CTG repeat contraction in Japanese DM is important for genetic counseling of Japanese DM families.

Adult↗
PubMed1995

Cloning, subcellular localization and expression of CHL1, a subunit of magnesium-chelatase in soybean.

Mg-insertion is the first committed step in chlorophyll synthesis and is catalyzed by Mg-chelatase. In photosynthetic bacteria, bchI gene product was suggested to be a subunit of Mg-chelatase. We isolated a bchI homolog from a soybean cDNA library and designated it as chlI. CHLI consisted of 421 amino acid residues and the sequence exhibited a high similarity to other BchI homologs. CHLI contained an ATP-binding motif found in other BchI homologs. CHLI was localized in the soluble fraction in soybean chloroplasts, suggesting that it was a stromal subunit of Mg-chelatase. chlI mRNA in cell culture (SB-P) of soybean was reversibly induced by light.

Adenosine Triphosphate↗
PubMed1995

Epidemiological and clinical features of Budd-Chiari syndrome in Japan.

The Japanese Ministry of Health and Welfare Research Committee on Aberrant Portal Blood Flow carried out an epidemiological survey and clinical study on Budd-Chiari syndrome in 1990. In the primary survey for determining the prevalence of the disease, a questionnaire was sent to all major hospitals throughout Japan and 160 cases seen in 1989 were compiled. More epidemiological details were obtained in 87 of these 160 cases. The number of patients with Budd-Chiari syndrome in this country was estimated to be about 300 (prevalence of 2.4/million) with about 20 new cases occurring every year. In the clinical study, 157 authentic cases of Budd-Chiari syndrome studied in 15 years (1975-89) were analyzed. There were 87 males (average age, 36.4 years) and 70 females (46.5 years), and the average period from the likely onset to the first medical consultation was 6.6 years, suggesting that these patients were mostly chronic cases. The main clinical features were hepatomegaly, leg edema, ascites and venous dilatation over the trunk. Abdominal pain was recorded in only four (2.5%). There were 16 (10.2%) with known identifiable etiologies. Of the patients 93% showed an obstructing lesion of various thickness in the hepatic portion of the inferior vena cava. Only nine (5.7%) had hepatic vein obstruction without caval lesions. Thus, the majority of Budd-Chiari syndrome patients in Japan are idiopathic, having an obstructing lesion in the inferior vena cava. The main causes of 33 deaths (21%) were liver failure, variceal bleeding and hepatocellular carcinoma. Hepatocellular carcinoma occurred in 10 (6.4%) in the 15-year period. However, the incidence of Budd-Chiari syndrome among all cases of hepatocellular carcinoma was less than 1% in the survey made by the Liver Cancer Study Group of Japan.

Adult↗
PubMed1995

Congenital myotonic dystrophy: molecular diagnosis and clinical study.

Recently, an unstable DNA fragment specific to myotonic dystrophy (MyD) was discovered. In affected individuals, a DNA fragment is found that is larger than in normal siblings. Our objectives were to show whether the results of DNA analysis agree with the disease severity and prognosis in congenital myotonic dystrophy (CMyD) by DNA analysis. We investigated three pregnancies (two studied retrospectively) in three families. We genotyped the family members with the Southern blots and the polymerase chain reaction (PCR) analysis. In one case a prenatal diagnosis was carried out using chorionic villus sampling. This report also presents the three cases of affected mothers and CMyD babies with their growth courses. We clarify four main problems in CMyD, namely, respiratory distress, delayed motor development, feeding difficulty, and delayed mental development. The allele size in the range of 10 to 13 kb tended to be present as the adult form of MyD, and 14 to 15 kb as the CMyD. The three CMyD cases whose alleles size in the range of 14 to 15 kb showed various forms of disease and prognosis. We reached the following conclusions: the disease severity and prognosis in babies with CMyD did not correlate with the result of DNA analysis. The DNA analysis is a useful test for prenatal diagnosis. However, it is impossible to predict the disease severity and prognosis in babies with CMyD.

Adult↗
PubMed1995

Cloning and characterization of the gene for a protein thiol-disulfide oxidoreductase in Bacillus brevis.

The gene (bdb) for protein thiol-disulfide oxidoreductase cloned from Bacillus brevis was found to encode a polypeptide consisting of 117 amino acid residues with a signal peptide of 27 residues. Bdb contains a well-conserved motif, Cys-X-X-Cys, which functions as the active center of disulfide oxidoreductases such as DsbA, protein disulfide isomerase, and thioredoxin. The deduced amino acid sequence showed significant homology with those of several bacterial thioredoxins. The bdb gene complemented the Escherichia coli dsbA mutation, restoring motility by means of flagellar and alkaline phosphatase activity. The Bdb protein overproduced in B. brevis was enzymatically active in both reduction and oxidization of disulfide bonds in vitro. Immunoblotting indicated that Bdb could function at the periphery of the cell.

Amino Acid Sequence↗
PubMed1995

Development of anti-Sm and anti-DNA antibodies followed by clinical manifestation of systemic lupus erythematosus in an elderly woman with long-standing Sjögren's syndrome.

A 69-year-old Japanese women who had been followed up for 10 years as a primary Sjögren's syndrome, is reported. She suddenly developed serological and clinical characteristics of systemic lupus erythematosus (SLE): anti-Sm and anti-dsDNA antibodies followed by nephrotic syndrome and pancytopenia. This case suggests that the diagnosis of primary Sjögren's syndrome should be considered as tentative in certain cases and that the development of serological characteristics precede and are associated with the development of clinical symptoms of SLE.

Aged↗