Biomedical subjects

S Natori

Publications and source records attributed to S Natori.

At least 127 records · Page 7Linked to original sources

PubMed1994

Cloning and identification of testis-specific transcription elongation factor S-II.

A new S-II cDNA clone was isolated from a rat testis library. This cDNA contained an open reading frame encoding 299 amino acid residues. The deduced amino- and carboxyl-terminal regions were very similar with those of Ehrlich cell S-II, which we reported previously, but the sequence of the intervening 46 amino acid residues was unique. This new S-II was expressed in the testis but not in the other rat tissues examined, suggesting that it was a testis-specific S-II. Recombinant testis-specific S-II produced in Escherichia coli was shown to stimulate RNA polymerase II.

Amino Acid Sequence↗

PubMed1994

Purification and characterization of ATBP, a novel protein that binds to A/T stretches in three segments of the Sarcophaga lectin gene.

A DNA-binding protein for the Sarcophaga lectin gene, ATBP (A/T-stretches-binding protein) was purified to homogeneity from the nuclear extract of NIH-Sape-4 cells. The molecular mass of ATBP determined under denaturing conditions was 53 kDa, but its native molecular mass estimated by gel-filtration chromatography was 430 kDa, suggesting that it is an octamer of the 53-kDa subunit. This protein bound to at least three DNA fragments from the Sarcophaga lectin gene, two of them are in the 5'-upstream region and the other is in a region containing an intron. These fragments are very AT rich and inlaid with stretches of A or T residues (A/T stretches). ATBP was found to have affinity for poly[d(A-T)]. These results suggest that ATBP binds to A/T stretches in the three DNA fragments from this gene. Furthermore, longer DNA was found to be bound more effectively, suggesting that an octamer of the 53-kDa subunit has multiple binding sites for the DNA fragments and requires a relatively long DNA sequence for binding.

Amino Acid Sequence↗

PubMed1994

Function of antimicrobial proteins in insects.

We have isolated and characterized various antimicrobial proteins from the haemolymph of Sarcophaga peregrina (flesh fly) larvae. Of these the sarcotoxin I family is a group of proteins mainly active against Gram-negative bacteria whereas sapecin is active mainly against Gram-positive bacteria. In addition to its function in defence, sapecin also plays a role in insect development. Recently, we identified a hendecapeptide of the sapecin homologue sapecin B that has the same antibacterial activity as the original sapecin B. Both sarcotoxin I and sapecin are inducible proteins synthesized de novo by the fat body and/or haemocytes and secreted into the haemolymph when the insect is in the acute phase response to bacterial infection. Antifungal protein (AFP) is constitutively present in the haemolymph and is active against certain fungi but not bacteria. These various antimicrobial proteins interact with microbial membranes. Sarcotoxin I interferes with membrane functions such as ATP synthesis and amino acid transport. The fungicidal activity of AFP is enhanced synergistically by sarcotoxin I, although sarcotoxin I alone has no appreciable antifungal activity. It is clear that the flesh fly has the ability to mount a potent defence response against microbial parasites by mobilizing several antimicrobial proteins.

Amino Acid Sequence↗

PubMed1994

Peptides derived from the granins (chromogranins/secretogranins).

This review summarizes the role of granins (chromogranins/secretogranins) as precursors to biologically active peptides. We discuss the structural basis of the proteolytic processing of the granins, the consequences of their processing and the biological effects of granin-derived peptides.

Amino Acid Sequence↗

PubMed1994

Purification of an insect defensin from the mosquito, Aedes aegypti.

Using a new, sensitive assay of bacterial growth inhibition, inducible antibacterial activity has been identified in the haemolymph of the mosquito, Aedes aegypti following inoculation with bacteria or with microfilariae of the filarial nematode Brugia pahangi, but not after inoculation with sterile culture medium. A lower level of antibacterial activity has also been observed in untreated individual mosquitoes. Following bacterial inoculation, a basic, inducible antibacterial peptide has been detected using native PAGE at pH 4, which corresponds with a 4.5 kDa peptide detected by tricine SDS-PAGE followed by silver staining. A peptide has been purified from immune haemolymph by ultrafiltration, followed by reversed-phase HPLC, yielding a single major peak with antibacterial activity. Partial amino acid sequence analysis of this fraction has revealed substantial homology with insect defensins. The data are consistent with the peptide being another member of this family, and we propose the name Aedes aegypti defensin.

Aedes↗

PubMed1994

Purification and molecular cloning of cDNA for an inducible antibacterial protein of larvae of a coleopteran insect, Holotrichia diomphalia.

Injection of Escherichia coli into larvae of the coleopteran Holotrichia diomphalia results in the appearance of antibacterial activity in the hemolymph. An antibacterial protein, named holotricin 2, was purified from larvae of this insect and characterized. A cDNA clone for holotricin 2 was isolated and its complete sequence was determined. This protein was found to inhibit the growth of Gram-negative bacteria and to consist of 72-amino acid residues with no cysteine residues. Its amino acid sequence is similar to that of coleoptericine, an antibacterial protein isolated from larvae of the coleopteran Zophobas atratus.

Amino Acid Sequence↗

PubMed1994

A prolyl endopeptidase of Sarcophaga peregrina (flesh fly): its purification and suggestion for its participation in the differentiation of the imaginal discs.

A prolyl endopeptidase that hydrolyses Suc-Gly-Pro-MCA (Suc, succinyl; MCA, methyl-coumaryl-7-amide) was purified to near homogeneity from NIH-Sape-4 cells derived from the flesh fly (Sarcophaga peregrina). The molecular mass of the purified enzyme was 84 kDa, and its activity was inhibited almost completely by 1 mM diisopropyl fluorophosphate (DFP). Immunoblotting and DFP-labeling experiments revealed that the leg imaginal discs of Sarcophaga contained this enzyme as a major serine proteinase. This prolyl endopeptidase is suggested to be involved in the differentiation of imaginal discs, because 2 mM DFP and 0.1 mM N-benzyloxycarbonyl-thioprolyl-thioprolynal-dimethylaceta l (ZTTA), a specific inhibitor for prolyl endopeptidase, inhibited differentiation of the imaginal discs from the eversion to the elongation stage.

Amino Acid Sequence↗

PubMed1994

Purification and molecular cloning of cDNA for an inducible antibacterial protein from larvae of the coleopteran, Tenebrio molitor.

Antibacterial activity was induced in the hemolymph of larvae of the coleopteran Tenebrio molitor by injection of Escherichia coli. An antibacterial protein, named tenecin 1, was purified to homogeneity from the larval hemolymph and characterized. A cDNA clone for tenecin 1 was isolated and its complete sequence was determined. This protein was found to inhibit the growth of Gram-positive bacteria and to consist of 43-amino acid residues including six cysteine residues. The disulfide structure of tenecin 1 was determined by sequencing cysteine containing peptides obtained by digesting tenecin 1 with endopeptidase Lys-C, trypsin, and thermolysin. The amino acid sequence and its disulfide bonds were similar to those of sapecin and sapecin C, antibacterial proteins of Sarcophaga peregrina.

Animals↗

PubMed1994

Induction of glutathione metabolism in the fat body of Sarcophaga peregrina by integumental injury.

When the body wall of Sarcophaga larvae was pricked to activate various defense protein genes, the glutathione level in the fat body was found to decrease significantly. Previously, we showed that these defense protein genes were activated when the fat body was incubated in buffered insect saline [Sugiyama and Natori (1991) Eur. J. Biochem. 200, 495-500]. Under these conditions, the glutathione level was also found to decrease significantly. Probably, the decrease of glutathione level is crucial for activation of insect NF-kappa B-like factor, which has been suggested to participate in the expression of various defense protein genes.

Animals↗

PubMed1994

[A case of myelodysplastic syndrome with pericarditis due to atypical Mycobacterium].

A 28-year-old woman with high fever and cough was admitted because of an abnormal shadow on the chest X-ray film. Mycobacterium kansasii was detected by sputum culture. The complete blood cell count disclosed pancytopenia and the myelogram showed slight hypoplasia and abnormality of the cell morphology. We diagnosed her disease as atypical mycobacteriosis and myelodysplastic syndrome. We began medical therapy with antituberculous drugs against Mycobacterium kansassi, and the sputum culture became negative. She was discharged after 4 months, but cardiothoracic ratio (CTR) increased gradually and pericardial effusion was detected by echocardiogram during follow-up. She was admitted again. We did not perform exploratory puncture, because the pericardial effusion did not increase for 6 months after admission and she had no complaints. We continued the antituberculous drugs, and CTR and the pericardial effusion decreased during follow-up. We considered the diagnosis in this case to be pericarditis due to Mycobacterium kansasii.

Adult↗

PubMed1993

Molecular cloning of cDNA for the 29 kDa proteinase participating in decomposition of the larval fat body during metamorphosis of Sarcophaga peregrina (flesh fly).

A cDNA clone for the 29 kDa proteinase participating in tissue disintegration during metamorphosis of Sarcophaga was isolated. This proteinase, named Sarcophaga cathepsin B, consisted of 256 amino acid residues, and contained three putative N-glycosylation sites. By comparison with other cathepsins B, its unique substrate specificity was partly explained by Ala at position 248.

Adipose Tissue↗

PubMed1993

Solution conformation of an antibacterial peptide, sarcotoxin IA, as determined by 1H-NMR.

The solution conformation of sarcotoxin IA, which is an antibacterial peptide isolated from Sarcophaga peregrina with a molecular mass of 4 kDa, was determined by NMR spectroscopy and hybrid distance geometry/dynamical simulated annealing calculations. On the basis of 227 experimental constraints, including 185 distance constraints obtained from NOE and 42 constraints associated with 21 hydrogen bonds, a total of 18 converged structures of sarcotoxin IA were obtained. The final 18 converged structures exhibit backbone-atomic root-mean-square differences about the averaged coordinate positions of 0.070 +/- 0.027 nm for residues 3-23 and 0.040 +/- 0.017 nm for residues 28-38. It has been indicated that sarcotoxin IA consists of two amphiphilic alpha-helical regions, i.e. helix I (Leu3-Gln23) and helix II (Ala28-Ala38), with a hinge region (Gly24-Ile27), which connects helix I and helix II. We conclude that these two amphiphilic helical segments of sarcotoxin IA are of importance for the expression of the antibacterial activity.

Amino Acid Sequence↗

PubMed1993

Purification, characterization, and cDNA cloning of an antifungal protein from the hemolymph of Sarcophaga peregrina (flesh fly) larvae.

An antifungal protein (AFP) was purified from the hemolymph of third instar larvae of Sarcophaga peregrina. This protein repressed the growth of Candida albicans in Sabouraud medium in the presence of nitrofurazone. However, in distilled water or saline, AFP alone killed C. albicans. Significant synergism was detected between AFP and sarcotoxin IA, an antibacterial protein of Sarcophaga. The lethal effect of AFP on C. albicans was greatly enhanced by the presence of a small amount of sarcotoxin IA. AFP was shown to bind to C. albicans and cause leakage of a substance(s) with absorbance at 260 nm from the cells. Analysis of its cDNA showed that AFP is a novel histidine-rich protein consisting of 67 amino acid residues.

Amino Acid Sequence↗

PubMed1993

Purification, sequence and antibacterial activity of two novel sapecin homologues from Sarcophaga embryonic cells: similarity of sapecin B to charybdotoxin.

Two sapecin homologues were purified from the culture medium of NIH-Sape-4, an embryonic cell line of Sarcophaga peregrina (flesh fly). These homologues contained six cysteine residues with exactly the same disulphide pairings as those in sapecin. The amino acid sequence of one of them, sapecin C, was also very similar to that of sapecin. The other homologue, sapecin B, was less similar to sapecin but showed significant similarity to charybdotoxin, an inhibitor of K+ channels isolated from a scorpion venom. Like sapecin, these homologues repressed the growth of various Gram-positive bacteria.

Amino Acid Sequence↗

PubMed1993

Transient appearance and localization of a 26-kDa lectin, a novel member of the Periplaneta lectin family, in regenerating cockroach leg.

A lectin consisting of a 26-kDa subunit was purified from the hemolymph of adult American cockroaches (Periplaneta americana) and shown to be a member of the Periplaneta lectin family. Immunoblotting analysis revealed that this lectin appeared transiently in regenerating legs after nymphal legs were amputated. Thus, its mode of appearance was similar to that of regenectin, another member of the Periplaneta lectin family. However, its time of appearance and localization in the regenerates were different from those of regenectin: the 26-kDa lectin appeared in regenerates in the middle stage of regeneration and was localized in the vicinity of the outside of newly formed epidermal cells. These results suggest that this lectin participates in the organization or stabilization of the epidermis during leg regeneration.

Animals↗

PubMed1993

Relaxation of supercoiled DNA associated with induction of heat shock proteins in Escherichia coli.

Heat treatment of wild-type Escherichia coli cells led to a transient relaxation of negatively supercoiled plasmid DNA and there was no recovery of DNA torsional strain in the DNA in gyrA mutant cells. After heat treatment, DnaK and GroEL proteins were synthesized continuously in the gyr A mutant cells, whereas they were synthesized only transiently in wild-type cells. Thus, change in superhelical density of the DNA correlated with the temperature-induced expression of heat shock proteins. Inhibitors of DNA gyrase (nalidixic acid, novobiocin), an organic solvent (ethanol) and a psychotropic drug (chlorpromazine) all stimulated relaxation of cellular DNA over the same concentration range that induces heat shock proteins. As DNA relaxation was induced by heat treatment or chemicals in an rpoH mutant, the process is not the result of induced synthesis of heat shock proteins.

Bacterial Proteins↗

PubMed1993

A novel role of Periplaneta lectin as an opsonin to recognize 2-keto-3-deoxy octonate residues of bacterial lipopolysaccharides.

1. Periplaneta lectin of the American cockroach was shown to have affinity to bacterial lipopolysaccharides (LPS) of chemotypes Rb-Re, but not to lipid A. 2. 2-Keto-3-deoxy octonate (KDO) was the most effective sugar so far tested for inhibition of the hemagglutinating activity of Periplaneta lectin. 3. Periplaneta lectin was suggested to participate in the clearance of bacteria injected into the abdominal cavity of the cockroach.

Animals↗

PubMed1993

Heat-induced DNA relaxation in vitro by mouse DNA topoisomerase I in the presence of ethidium bromide.

In general, covalently-closed circular DNAs that are relaxed by DNA topoisomerase I at higher temperatures are more negatively (or less positively) supercoiled when analyzed at the same temperature. We found that in the presence of ethidium bromide the reaction products were less negatively supercoiled at higher temperatures. Consequently, the linking number of substrate DNA changed reversibly with temperature-shift: DNA relaxation occurred on temperature shift-up, and re-supercoiling on temperature shift-down. Analyses of the migration of covalently closed circular DNA on agarose gel electrophoresis and of the fluorescence intensity of ethidium bromide bound to DNA indicated decrease in binding of the drug to DNA at higher temperatures. Thus, the thermal effects on the topology of the reaction products of mouse DNA topoisomerase I in the presence of ethidium bromide can be explained by the temperature-sensitive interaction of the drug with DNA.

Animals↗