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Biomedical subjects

S Natori

Publications and source records attributed to S Natori.

At least 181 records · Page 10Linked to original sources
PubMed1990

Production of recombinant sarcotoxin IA in Bombyx mori cells.

A cDNA for sarcotoxin IA, an antibacterial protein of Sarcophaga peregrina (fleshfly), was inserted into a silkworm baculovirus vector and expressed in Bm-N cells, a line of Bombyx mori cells. When a cysteine proteinase inhibitor, p-chloromercuribenzenesulphonic acid, was present in the culture medium, a significant amount of recombinant sarcotoxin IA accumulated, but without this reagent the product seemed to be degraded in this system. The C-terminus of the recombinant sarcotoxin IA seemed to be glycine, not amidated arginine as found in authentic sarcotoxin IA. Probably, Bm-N cells lack the C-terminal alpha-amidation enzyme.

Animals↗
PubMed1990

1H nuclear magnetic resonance study of the solution conformation of an antibacterial protein, sapecin.

The solution conformation of an antibacterial protein sapecin has been determined by 1H nuclear magnetic resonance (NMR) and dynamical simulated annealing calculations. It has been shown that the polypeptide fold consists of one flexible loop (residues 4-12), one helix (residues 15-23), and two extended strands (residues 24-31 and 34-40). It was found that the tertiary structure of sapecin is completely different from that of rabbit neutrophil defensin NP-5, which is homologous to sapecin in the amino acid sequences and also has the antibacterial activity. The three-dimensional structure determination has revealed that a basic-residue rich region and the hydrophobic surface face each other on the surface of sapecin.

Amino Acid Sequence↗
PubMed1990

Site-directed mutagenesis of arginine 246, glutamic acid 247, and histidine 248 in the eukaryotic transcription factor S-II.

When His248 of the transcription factor S-II was replaced by alanine or tyrosine, the activity of the resulting mutants was less than 30% of that of the wild-type S-II. When Arg246, Glu247, and His248 were all replaced by leucine, the resulting mutant showed complete loss of activity. These results indicate that the amino acid sequence Arg-Glu-His at positions 246-248 of S-II is important for its stimulatory activity. The mutant S-II with no activity could not form a complex with RNA polymerase II, unlike wild-type S-II, but retained ability to interact with DNA.

Amino Acid Sequence↗
PubMed1990

Purification and characterization of lipopolysaccharide-binding protein from hemolymph of American cockroach Periplaneta americana.

A protein having affinity to lipopolysaccharide of Escherichia coli K12 was purified to homogeneity from the hemolymph of Periplaneta americana. This protein, with an average molecular mass of 450 kDa. was a homooligomer of a 28-kDa subunit protein. Comparative studies using lipopolysaccharide molecules of E. coli and Salmonella minnesota suggested that this protein recognizes and binds to a specific carbohydrate structure of E. coli lipopolysaccharide. Ca2+ was required for this protein to bind to lipopolysaccharide, but other divalent cations could not replace Ca2+.

Acute-Phase Proteins↗
PubMed1990

Mutagenicity of isoquinoline alkaloids, especially of the aporphine type.

The mutagenicity of 44 isoquinoline alkaloids was tested in Salmonella typhimurium TA100 and TA98 in the presence or absence of S9 mix. The alkaloids tested included compounds from the isoquinoline, benzylisoquinoline, bisbenzylisoquinoline, monoterpene isoquinoline, berberine, morphinane, hasubanan, benzo[c]phenanthridine and aporphine groups. Among the alkaloids tested, liriodenine was the most potent mutagen for TA100 and roemerine was the most potent for TA98. A clear structure-mutagenicity relationship was observed in a series of aporphine alkaloids (aporphine, dehydroaporphine, 7-oxoaporphine and 4,5-dioxoaporphine), and 10,11-non-substituted aporphines were suggested to exert their mutagenicity through metabolic activation of the 10,11 positions, possibly as the 10,11-epoxides.

Alkaloids↗
PubMed1990

Secretory protein 7B2. A novel tumor marker of medullary carcinoma of the thyroid.

Mean plasma concentrations of 7B2 in three patients with medullary carcinoma of the thyroid (MCT) (294 +/- 38 pg/ml) were significantly higher than those in age-matched normal subjects (107.2 +/- 7.2 pg/ml, n = 11). The intravenous infusions of pentagastrin (0.5 microgram/kg) markedly increased the plasma concentrations of 7B2 as well as calcitonin in all three MCT patients but it caused no significant rise of the plasma 7B2 concentration in any healthy subjects. The peak times and rates of increase of plasma 7B2 concentrations were different from those of plasma calcitonin concentrations in MCT patients. The plasma 7B2 concentration in one of the patients with MCT showed a marked reduction and no further elevation from the pentagastrin infusion following a total thyroidectomy (preop. 226 pg/ml; postop. 112.1 pg/ml). The above evidence suggests that the increased levels of plasma 7B2 in MCT patients may be attributed to the release from parafollicular cells of thyroid. Therefore, 7B2 is considered to be clinically useful as a tumor marker of MCT.

Adolescent↗
PubMed1990

Purification and properties of a beta-galactoside-binding lectin from neonatal marmoset.

A beta-galactoside-binding lectin was extracted from whole neonatal marmoset homogenate with lactose solution and purified to homogeneity by ion-exchange chromatography on Q Sepharose Fast Flow and by affinity adsorption to trypsinized and glutaraldehyde-fixed ghosts of rabbit erythrocytes. The lectin has a dimeric structure composed of two 15K subunits. Its amino acid composition and partial amino acid sequences were quite similar to those of beta-galactoside-binding lectins from human placenta and lung.

Amino Acid Sequence↗
PubMed1990

Determination of the disulfide array in sapecin, an antibacterial peptide of Sarcophaga peregrina (flesh fly).

Sapecin is a 40-residue peptide containing 6 half-cystine residues. The disulfide structure of sapecin was determined by sequencing cystine-containing peptides obtained by digesting sapecin with thermolysin. Results showed that sapecin has a vortical structure fixed by 3 disulfide bonds between cysteine residues 3 and 30, 16 and 36, and 20 and 38, respectively, and that these disulfide bonds are essential for its antibacterial activity.

Amino Acid Sequence↗
PubMed1990

Mode of action of sapecin, a novel antibacterial protein of Sarcophaga peregrina (flesh fly).

Sapecin is an antibacterial protein purified from the culture medium of NIH-Sape-4, an embryonic cell line of Sarcophaga peregrina [Matsuyama, K. & Natori, S. (1988) J. Biol. Chem. 236, 17112-17116]. As this protein inhibited the growth of Gram-positive bacteria better than that of Gram-negative bacteria, we studied its mode of action with special reference to its effects on S. aureus and Escherichia coli. Results showed that sapecin had high affinity for cardiolipin, which is a major phospholipid of S. aureus. Moreover, a mutant of E. coli with a defect in cardiolipin synthesis was more resistant to sapecin than wild type E. coli, suggesting that cardiolipin is a target for sapecin. Lipopolysaccharide of E. coli was also found to be a barrier for the antibacterial activity of sapecin.

Animals↗
PubMed1990

Effect of octapeptide somatostatin analogue (SMS 201-995) on plasma 7B2 (a neuroendocrine polypeptide) levels in patients with acromegaly.

We studied the sequential changes of plasma levels of immunoreactive '7B2' (IR-7B2), a neuroendocrine polypeptide, after a subcutaneous injection of 50 micrograms of synthetic octapeptide somatostatin analogue (SMS 201-995) in seven patients with acromegaly due to GH-producing pituitary adenoma. Compared to the basal levels, mean plasma IR-7B2 and GH levels significantly decreased, until 5 and 10 h respectively after the administration of SMS 201-995. The mean (+/- SEM) nadir levels of plasma IR-7B2 and GH were 68.1 +/- 10.1 and 13.1 +/- 6.9%, respectively, compared to mean plasma levels before treatment (100%). Plasma IR-7B2 as well as GH levels did not change significantly when saline was administered subcutaneously to three acromegalic patients. In addition, plasma IR-7B2 levels did not change significantly after the administration of SMS 201-995 in normal subjects or in patients with primary hypothyroidism in whom SMS 201-995 induced a decrease of plasma TSH levels. These results strongly suggest that SMS 201-995 has an unequivocal suppressive effect on the synthesis and/or the secretion of 7B2 in human somatotroph adenoma cells.

Acromegaly↗
PubMed1990

Analysis of a gene cluster for sarcotoxin II, a group of antibacterial proteins of Sarcophaga peregrina.

Sarcotoxin II is a group of antibacterial proteins of Sarcophaga peregrina (flesh fly) with related primary structures. We have cloned three genes in this family. These genes formed a tandem array with about 2-kb intervals, and one of them was present in the opposite strand. The putative amino acid sequences of the proteins encoded by these genes were very similar except for a deletion in one of them. All of the genes were found to be activated transiently in the same way when the larval body wall was injured, suggesting that the encoded proteins are acute-phase-responsive proteins for protecting the insect from bacterial infection.

Amino Acid Sequence↗
PubMed1990

The effects of new cytochalasins from Phomopsis sp. and the derivatives on cellular structure and actin polymerization.

The effects of ten 10-phenyl-[11]cytochalasins produced by Phomopsis sp. including novel compounds having 5,7- or 6,7-glycol structures and their derivatives, on the cell morphology and actin distribution in C3H-2K cells, as well as on lymphocyte capping and actin polymerization, were examined. The structure-activity relationship reported in the previous papers has been confirmed. The novel glycol type compounds showed little or no activity, suggesting the importance of the perhydroisoindol-1-one nucleus for the manifestation of the cytochalasin actions.

Actins↗
PubMed1990

[Anti-tumor factor in insects' hemolymph].

We have purified a lectin from the hemolymph of Sarcophaga peregrina larvae, obtained after injury of their body wall. This lectin recognizes galactose residues and suggested to be involved in the defense mechanism of this insect. We also demonstrated that this lectin induced cytotoxic effects on tumor cells in the presence of murine macrophages. It was found that the murine macrophages had Sarcophaga lectin binding proteins. Using pupal hemocytes and fatbody of this insect, we established an in vitro system that mimics dissociation of the fatbody in vivo. New membrane protein, induced on the surface of the hemocytes at pupation, suggested to participate in the recognition of the fatbody.

Animals↗
PubMed1989

Cloning and in vitro transcription of the Sarcophaga lectin gene.

A genomic clone for the Sarcophaga lectin gene was isolated. This gene was a compact single copy gene. Two transcription initiation sites were located by S1 nuclease mapping and primer extension. However, transcription from one of these initiation sites was much greater than that from the other site under all conditions in which this gene was expressed. This gene was found to be transcribed efficiently in a nuclear extract of NIH-Sape-4 cells, an embryonic cell line of Sarcophaga synthesizing Sarcophaga lectin constitutively, but not in that of Ehrlich ascites tumor cells. These results suggested that the former extract contains a specific transcription factor(s) for this gene that is not present in the nuclear extract of Ehrlich cells.

Amino Acid Sequence↗
PubMed1989

Cloning of a housekeeping-type gene (MER5) preferentially expressed in murine erythroleukemia cells.

DNA complementary to mRNA preferentially produced in murine erythroleukemia (MEL) cells was cloned from a cDNA library of anemic mouse spleen mRNAs. An open reading frame was noted in the cloned DNA, and was tentatively designated MER5. The MER5 mRNA is abundant in three MEL cell lines, but less in other tissues or cell lines. The levels of the MER5 mRNA changed periodically during MEL cell differentiation and decreased as globin mRNA accumulated. The MER5 promoter region contained no typical TATA-like sequence, but possible target sequences for AP1, AP2, SP1 and octamer-binding protein. More interestingly, this promoter contained the duplicated CACCC boxes, which are common in the adult beta-globin promoter from many species, but uncommon for promoters of other eukaryotic genes.

Amino Acid Sequence↗
PubMed1989

Stage-specific detection of a DNA-binding protein for the storage protein gene of Sarcophaga peregrina.

A nuclear extract of fat body prepared from third instar larvae of Sarcophaga peregrina (flesh fly) was found to contain a DNA-binding protein that specifically bound to 5'-upstream region of the storage protein (arylphorin) gene. This protein was found only in larvae harvested 46 h after larval emergence, indicating that its appearance was strictly regulated by the developmental stage of the insect. Since the storage protein gene is actively transcribed in the fat body at this stage, this protein is probably a specific transcription factor for the storage protein gene. DNase I footprinting analysis showed that the nucleotide sequence of the binding site of this protein is ACCACAACA, which is located at residues -247 to -255 upstream of the +1 site. Results indicated that formation of the DNA-protein complex required Zn2+.

Animals↗
PubMed1989

Production of functional S-II in Bombyx mori cells.

A cDNA for murine transcription factor S-II (Hirashima et al., J. Biol. Chem (1988) 263, 3858-3863) was inserted into a silkworm baculovirus vector and expressed in Bm-N cells, a cell line of Bombyx mori maintained in the laboratory. Recombinant S-II was purified from virus-infected cell extracts to near homogeneity by ammonium sulfate fractionation, and chromatographies on DEAE-cellulose and phosphocellulose. About 60 micrograms of recombinant S-II was obtained from 1 g of virus-infected cells. The molecular mass and specific activity of recombinant S-II were exactly the same as those of authentic S-II purified from Ehrlich ascites tumor cells.

Animals↗