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Biomedical subjects

H Yamagata

Publications and source records attributed to H Yamagata.

At least 163 records · Page 9Linked to original sources
PubMed1984

Anti-La/SSB antibody is present in some normal sera and is coincident with anti-Ro/SSA precipitins in systemic lupus erythematosus.

Sera from 42 patients with systemic lupus erythematosus (SLE) and precipitating antibody to the La/SSB antigen contained 80,000 to 28,800,000 times the minimum detectable binding activity (units) in a solid phase ELISA assay using purified La/SSB antigen. Three normal sera (of 40 tested) had 7,200,21,600 and 21,100 units, respectively, while the log average of the 40 normals was 270 units. Binding activity in normal sera was in the F(ab')2 fragments of IgG, inhibited by purified La/SSB antigen, and bound the major La/SSB peptides. The average apparent relative binding affinity to La/SSB in normal donors was 10-fold lower than in SLE patients with anti-La/SSB precipitins. Analysis of other SLE sera revealed a high incidence of anti-La/SSB in association with anti-Ro/SSA precipitins.

Antibodies, Antinuclear↗
PubMed1983

Cloning and expression of a gene coding for the prolipoprotein signal peptidase of Escherichia coli.

An Escherichia coli mutant, Y815, has a temperature-sensitive prolipoprotein signal peptidase. IPTG-induced synthesis of the major outer membrane prolipoprotein (PLP) results in the inhibition of cell growth because of accumulation of PLP in its envelope [J. Bacteriol. (1982) 152, 1163-1168]. The 2000 E. coli strains of Clarke and Carbon's collection were screened for the presence of a plasmid complementing the IPTG-sensitivity of the growth of Y815. One plasmid, pLC3-13, complemented the IPTG-sensitivity. The envelope fraction prepared from Y815 transformed by pLC3-13 showed high activity of the PLP signal peptidase in vitro at high temperature. A 4 kb AccI fragment subcloned onto plasmid pHY001 was shown to carry the gene for the PLP signal peptidase.

Chromosome Mapping↗
PubMed1983

The precipitating antibody to an acidic nuclear protein antigen, the Jo-1, in connective tissue diseases. A marker for a subset of polymyositis with interstitial pulmonary fibrosis.

The clinical significance of antibodies to the Jo-1 antigen in connective tissue diseases was studied. Clinical diagnoses of 11 patients who had anti-Jo-1 antibody were: polymyositis 8, dermatomyositis 1, and overlap syndrome 2 (polymyositis--systemic lupus erythematosus 1, polymyositis--scleroderma 1). All the patients who had anti-Jo-1 antibody showed interstitial pulmonary fibrosis, and in 2 patients anti-Jo-1 antibodies were detected before the appearance of lung disease.

Adult↗
PubMed1983

Genetic characterization of a gene for prolipoprotein signal peptidase in Escherichia coli.

A mutation (lspA, prolipoprotein signal peptidase) rendering the prolipoprotein signal peptidase temperature-sensitive in Escherichia coli has been analyzed. The mutation was mapped in the dnaJ-rpsT-ileS-dapB region by interrupted mating with various Hfr strains and P1 phage transduction. lambda transducing phage lambda ddapB2 that carries the rpsT-ileS-dapB region was shown to complement the lspA mutation. Plasmid pLC3-13 which had been isolated from Clarke and Carbon's collection as a plasmid carrying the lspA locus was shown to carry the dnaJ and rpsT loci. Complementation analysis with plasmids carrying various DNA fragments derived from pLC3-13 showed that the lspA locus is between the rpsT and ileS loci. The wildtype allele was dominant over the lspA allele.

Bacteriophage lambda↗
PubMed1983

Temperature-sensitive prolipoprotein signal peptidase in an Escherichia coli mutant: use of the mutant for an efficient and convenient assay system.

Escherichia coli mutant Y815 accumulates the precursor of lipoprotein (prolipoprotein) in its envelope. The accumulated prolipoprotein could be chased to mature lipoprotein at 30 degrees C but not at 60 degrees C (Yamagata, H., Ippolito, C., Inukai, M., & Inouye, M. (1982) J. Bacteriol. 152, 1163). When the envelope fraction prepared from the mutant was mixed with the envelope fraction prepared from wild-type E. coli cells and incubated at 60 degrees C in the presence of Triton X-100, the prolipoprotein in the mutant envelope fraction was cleaved rapidly to mature lipoprotein. The cleavage was dependent on the addition of wild-type envelope fraction and Triton X-100 to the reaction mixture. This indicated that the prolipoprotein accumulated in the mutant envelope is a good substrate for the signal peptidase which cleaves the signal peptide from the prolipoprotein, and hence the accumulation of prolipoprotein was due to lack of the signal peptidase in the mutant. The optimum concentration of Triton X-100 for the cleavage of the prolipoprotein in the above in vitro system was 0.05 to 0.1% (v/v) at a wild-type envelope concentration of 0.35 mg protein/ml. Prolipoprotein accumulated in wild-type cells on treatment with globomycin, a specific inhibitor of the signal peptidase, was also cleaved to mature lipoprotein under the same conditions. Triton X-100 was shown to solubilize the signal peptidase from the envelope fraction. The cleavage of the prolipoprotein was rapid and complete in the in vitro system described here, which provides an efficient and convenient assay system for the solubilized signal peptidase for prolipoprotein.

Anti-Bacterial Agents↗
PubMed1983

Inhibition of secretion of a mutant lipoprotein across the cytoplasmic membrane by the wild-type lipoprotein of the Escherichia coli outer membrane.

A globomycin-resistant mutant of Escherichia coli was found to produce a precursor of the major outer membrane lipoprotein (prolipoprotein), in which the glycine residue at position 14 within the signal peptide was replaced by an aspartic acid residue. The same mutation has been reported by Lin et al. (Proc. Natl. Acad. Sci. U.S.A. 175:4891-4895, 1978). The structural gene of the mutant prolipoprotein was inserted into an inducible expression cloning vehicle. When the mutant prolipoprotein was produced in lipoprotein-minus host cells, 82% of the unprocessed protein was found in the membrane fraction, with the remaining 18% localized in the soluble fraction. However, when the production of the mutant prolipoprotein was induced in the wild-type lpp+ host cells, only 31% of the mutant prolipoprotein was found in the membrane fraction, leaving the remaining 69% in the soluble, cytoplasmic fraction. In addition, the assembly of the wild-type lipoprotein in these cells was not affected, whether the mutant prolipoprotein was produced or not. These results suggest that secretions of both mutant and wild-type prolipoproteins utilize the same component(s) responsible for the initial stages of secretion across the cytoplasmic membrane. However, it appears that the wild-type lipoprotein has a higher affinity for these components than does the mutant lipoprotein.

Anti-Bacterial Agents↗
PubMed1983

Genetic transformation of Bacillus brevis 47, a protein-secreting bacterium, by plasmid DNA.

A method has been developed for introducing plasmid DNA into Bacillus brevis 47, a protein-secreting bacterium. Treatment of B. brevis 47 cells with 50 mM Tris-hydrochloride buffer of alkaline pH was effective for inducing DNA uptake competence. In the presence of polyethylene glycol, the Tris-treated cells incorporated plasmid DNA with a frequency of 10(-4) (transformants per viable cell) when 1 microgram of plasmid DNA was added to 10(9) Tris-treated cells. The pH of Tris-hydrochloride buffer as well as the concentration and molecular weight of the polyethylene glycol affected the transformation frequency. The growth phase of B. brevis 47 cells strongly influenced the frequency. Two plasmids, pHW1 and pUB110, have been introduced into B. brevis 47 by this method. The mechanism of induction of competence for DNA uptake in connection with removal of the outer two protein layers of the cell wall by treatment of B. brevis 47 cells with Tris-hydrochloride buffer is discussed.

Bacillus↗
PubMed1982

Biosynthesis of storage proteins in developing rice seeds.

Sodium dodecyl sulfate-polyacrylamide gel electrophoretic analysis of the starchy endosperm protein of rice (Oryza sativa L. Japonica cv Koshihikari) during seed development confirmed that storage protein begins to accumulate about 5 days after flowering. Two polypeptide groups, 22 to 23 and 37 to 39 kilodaltons, the components of glutelin, the major storage protein in rice seed, appeared 5 days after flowering. A 26-kilodalton polypeptide, the globulin component, also appeared 5 days after flowering. Smaller polypeptides (10- to 16-kilodaltons) including prolamin components, appeared about 10 days after flowering. In contrast, the levels of the 76- and 57-kilodalton polypeptides were fairly constant throughout seed development. Transmission electron microscopy and fractionation by sucrose density gradient centrifugation of the starchy endosperms at various stages of development showed that protein body type II, the accumulation site of glutelin and globulin, was formed faster than protein body type I, the accumulation site of prolamin.The 57-kilodalton polypeptide but not the glutelin subunits was labeled in a 2-hour treatment with [(14)C]leucine given between 4 and 12 days after flowering to developing ears. In vivo pulse-chase labeling studies showed the 57-kilodalton polypeptide to be a precursor of the 22 to 23 and 37 to 39 kilodalton subunits. The 57-kilodalton polypeptide was salt-soluble, but the mature glutelin subunits were almost salt insoluble.In vitro protein synthesis also showed that the mRNAs directly coding the 22 to 23 and 37 to 39 kilodalton components were absent in developing seeds and that the 57-kilodalton polypeptide was the major product. Thus, it was concluded that the two subunits of rice glutelin are formed through post-translational cleavage of the 57-kilodalton polypeptide.

Journal Article↗
PubMed1982

Temperature-sensitive processing of outer membrane lipoprotein in an Escherichia coli mutant.

A mutant of Escherichia coli that accumulated prolipoprotein, a secretory precursor of the outer membrane lipoprotein, was isolated. The prolipoprotein accumulated in this mutant was modified by glyceride, but the in vitro cleavage of the signal peptide of the accumulated prolipoprotein was found to be temperature sensitive. The mutation appears to be located outside the gene for the lipoprotein, thus suggesting that the gene for the signal peptidase for the prolipoprotein was mutated.

Bacterial Outer Membrane Proteins↗
PubMed1981

Comparison of the lipoprotein gene among the Enterobacteriaceae. DNA sequence of Erwinia amylovora lipoprotein gene.

A DNA sequence of 816 base pairs encompassing the entire Erwinia amylovora lipoprotein gene was determined. Sequence comparison between E. amylovora, Escherichia coli, and Serratia marcescens suggests that the structure of the lipoprotein has been highly conserved under the constraint of efficient gene expression selecting promoter structure, mRNA secondary structure, and codon usage in addition to the polypeptide function. The sequence also suggests that the lpp gene of the three bacteria diverged sequentially in the course of evolution.

Base Sequence↗
PubMed1981

Characterization of a high molecular weight acidic nuclear protein recognized by autoantibodies in sera from patients with polymyositis-scleroderma overlap.

Autoantibodies in the serum from a patient with connective tissue disease have been used to define a high molecule weight acidic nuclear protein antigen. The antigen tentatively termed Ku, after the first two letters of patient's name, has distinct physicochemical properties and immunological specificities that distinguish it from previously reported antigens. The Ku antigen has an apparent 300,000 mol wt as determined by gel filtration and sucrose density gradient ultracentrifugation techniques. The antigen is destroyed by trypsin, mild heating, and pH variations greater than 10 and less than 5. Treatment with ribonuclease or deoxyribonuclease did not affect the antigenic reactivity. The Ku antigen was demonstrated in the soluble extracts of human, calf, and rabbit, but not of rat tissues. Purified antibody localized the Ku antigen within the nuclei of human liver where a "reticular" pattern of immunofluorescence was seen. Of 330 patients with various connective tissue diseases, 9 had precipitating antibodies to the Ku antigen. Preliminary results of clinical analysis indicated that antibody to the Ku antigen might become a useful marker for a group of patients with clinical characteristics of both polymyositis and scleroderma with a good prognosis.

Antigens↗
PubMed1980

Deletion mapping and heterogenote analysis of a mutation responsible for osmosis-sensitive growth, spectinomycin resistance, and alteration of cytoplasmic membrane in Escherichia coli.

Lambda transducing phages carrying Escherichia coli deoxyribonucleic acid of various lengths from the aroE-rpsL region were lysogenized into the F'3 plasmid and were used for heterogenote analysis of YM101, a sucrose-dependent, spectinomycin-resistant mutant of E. coli. Three characteristics of the mutant strain, resistance to spectinomycin, sucrose dependence of growth, and lack of I-19 protein in the cytoplasmic membrane, were shown to be the result of a mutation in a region designated delta 53-spcl. This region extends over 3.6-kilobase pairs and is located within a cluster of ribosomal genes. The mutation is recessive to the wild-type allele.

Bacterial Proteins↗