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K Takeishi

Publications and source records attributed to K Takeishi.

At least 55 records · Page 3Linked to original sources
PubMed1981

Isolation and characterization of small nuclear RNAs from Dictyostelium discoideum.

Low molecular weight RNAs were isolated from nuclei of the cellular slime mold Dictyostelium discoideum AX-3. Analysis of the RNAs by polyacrylamide gel electrophoresis showed that the vegetative cell nuclei contained, besides tRNA (Dd1), 5S RNA (Dd4), and 5.8S RNA (Dd7), at least 7 small RNA species (Dd3, Dd5, Dd6, Dd8, Dd9, Dd10, Dd11) of 4S to 8S as major components and that the 7 small RNAs were localized mainly in the nucleus and had no poyl(A) sequence. These nuclear RNA species were metabolically stable, as shown by a chase experiment. Dd6, Dd8, and Dd9 had similar gel electrophoretic mobilities to those of the small nuclear RNA species U1, U2, and U3, respectively, of rat liver. Analysis of the 5'-terminus of these RNA molecules with tobacco acid phosphodiesterase suggested that Dd6, Dd8, and Dd9 each contain a cap. Sequence analysis of the 3'-end labeled Dd9 RNA showed that the 3'-terminal region sequenced had sequence homology with that of rat Novikoff hepatoma U3 RNA. These results indicate that Dictyostelium nuclei contain a set of small nuclear RNA species which is structurally similar to that in mammalian cells. No qualitative differences were detected between the small nuclear RNA species of vegetative and early differentiating cells.

Animals↗
PubMed1981

Species difference in liver microsomal and cytosolic enzymes involved in mutagenic activation of N-hydroxy-N-2-fluorenylacetamide.

The mutagenic activations of N-hydroxy-N-2-fluorenylacetamide (N-OH-2-FAA) by subcellular fractions of the livers of the Sprague-Dawley rat, C57BL mouse, Hartley guinea pig, Syrian golden hamster, and Macaca fuscata fuscata monkey were examined for sensitivity to paraoxon, which inhibits a deacetylase but not an arylhydroxamic acid acyltransferase. The mutagenic activation by liver microsomes was almost entirely mediated by a paraoxon-sensitive enzyme in all the animals tested. In contrast, the mutagenic activation by liver cytosol was mediated mostly by a paraoxon-sensitive enzyme in mice and guinea pigs, mostly by a paraoxon-resistant enzyme in rats and hamsters, and by both enzyme types in the monkey. In rats and guinea pigs, attempts were made to identify the enzymes causing mutagenic activation in the liver cytosol by a comparison of the elution positions of these enzymes in gel filtration and DEAE-cellulose column chromatography with those of known enzymes. In the rat liver cytosol, the mutagenic activation was mediated not only by acyltransferase but also by an unknown enzyme, which was resistant to paraoxon and differed from acyltransferase in chromatographic behavior. In the guinea pig liver cytosol, the activation was due to deacetylase activities, which could be separated into four fractions by gel filtration. These data indicate that species differ in the kinds of liver cytosolic enzymes involved in mutagenic activation of N-OH-2-FAA but not in the kind of liver microsomal enzyme involved.

2-Acetylaminofluorene↗
PubMed1980

Structural changes in the glutamine-chargeable Escherichia coli transfer RNA-Trp produced by chemical modification with sodium bisulfite.

Glutamine-mischargeable tRNA produced by sodium bisulfite-treated Escherichia coli tRNA-Trp was isolated by dihydroxyboryl-cellulose affinity column chromatography. This tRNA was shown to have dual specificity tryptophan and glutamine, and, when charged with either amino acid, bound to ribosomes in response to the non-sense codon UAG but not in response to the tryptophan codon UGG. The results were consistent with the reported properties of Su+7 tRNA. The bisulfite-treated tRNA-Trp migrated as two bands during polyacrylamide gel electrophoresis. The faster moving band (band I) coincided with that of untreated tRNA-Trp. The slower moving band (band II) coincided with the glutamine-chargeable tRNA-Trp. Su+7 tRNA behaved like band II tRNA upon gel electrophoresis. Nucleotide sequence analysis showed that a cytidine-uridine transition occurred at the 1st or the 2n position of the anitcodon of band II tRNA. Band I and band II tRNAs differed from each other in their thermal melting profiles. It is suggested that the single base change in the anticodon is responsible for the altered conformation of band II tRNA.

Autoradiography↗
PubMed1980

Messenger ribonucleic acid of the lipoprotein of the Escherichia coli outer membrane. II. The complete nucleotide sequence.

The complete nucleotide sequence of the mRNA for the outer membrane lipoprotein from Escherichia coli has been determined. All the ribonuclease T1 and ribonuclease A fragments obtained from the mRNA were connected with DNA sequencing of restriction endonuclease fragments of the cloned lipoprotein gene. The mRNA consists of 322 nucleotides, and there are 38 and 50 nucleotides in the 5' and 3' end untranslated regions, respectively. The mRNA has several unique features: (a) Out of 50 possible codons for 15 amino acids in the prolipoprotein only 25 codons are used, and all of these appear to be read by the major isoaccepting species of tRNAs for individual amino acids. (b) In the first 64 nucleotides from the 5' end, there are no obvious secondary structures. On the other hand, between the 65th nucleotide and the 3' end, 85% of the nucleotides are involved in the formation of secondary structures, with nine stable stem-and-loop structures. (c) There are many repeating sequences including one repeat of 40 nucleotides. (d) There are a few other features which could be important for efficient translation of the mRNA.

Base Sequence↗
PubMed1979

Mutagenic activation of 2-acetylaminofluorene by guinea-pig liver homogenates: essential involvement of cytochrome P-450 mixed-function oxidases.

2-Acetylaminofluorene (AAF) was highly mutagenic to Salmonella typhimurium strain TA98, when activated by a liver post-mitochondrial supernatant fraction (S9 fraction) from guinea-pigs, in spite of the resistance of this species to AAF carcinogenesis and the low capacity of the liver of this species for N-hydroxylation of AAF. The mutagenicity was comparable to or higher than that resulting from activation by mouse- or rat-liver S9 fraction, and was not enchanced by treatment with cytochrome P-450 inducers, a combination of phenobarbital and 5,6-benzoflavone. In an attempt to understand this unexpected result we examined whether a cytochrome P-450 mixed-function oxidase system participated in the mutagenic activation of AAF by guinea-pig liver, as it does in the case of mouse liver. The mutagenic activation was: (1) completely dependent on the addition of a co-factor, NADPH, to the mutation assay system, (2) completely suppressed by antiserum against NADPH--cytochrome c reductase, and (3) sensitive to a cytochrome P-450 inhibitor, 7,8-benzoflavone. These results indicate that the cytochrome P-450 enzyme system is essentially involved even in the mutagenic activation of AAF by guinea-pig-liver S9 fraction. Based on both the present and other data, the mechanism of the mutagenic activation is discussed to explain the observed high mutagenic potential of AAF in the presence of guinea-pig-liver S9 fraction.

2-Acetylaminofluorene↗
PubMed1979

Differential effect of a microsomal deacetylase inhibition on the mutagenicity in Salmonella typhimurium of 2-acetylaminofluorene by liver homogenates of guinea pigs, mice and rats.

The effect of paraoxon, a microsomal deacetylase inhibitor, on the mutant genicity of 2-acetylaminofluorene (AAF) by liver homogenates was compared between the AAF carcinogenesis-resistant guinea pigs and the susceptible mice and rats. The mutagenicity of AAF was mostly abolished by paraoxon, not only in the 3 kinds of untreated animals but also in guinea pigs treated with a combination of phenobarbital and 5,6-benzoflavone, whereas about 50% of the mutagenicity was resistant to paraoxon in treated mice and rats. We suggest that microsomal deacetylase activity is crucially involved in the mutagenic activation of AAF by guinea pig liver homogenates, while the enzyme activity other than the deacetylase activity is also important in the activation by liver homogenates from treated mice or rats.

2-Acetylaminofluorene↗
PubMed1979

Low molecular weight nuclear RNA species in Dictyostelium discoideum.

Low molecular weight nuclear RNA (snRNA) species present in Dictyostelium discoideum Ax-3 cells were examined by electrophoresis in polyacrylamide slab gels. Dictyostelium nuclei were found to contain almost as many snRNA species as mammals and their electrophoretic pattern was similar to that of snRNA in mammalian cells. The same results were obtained with snRNA prepared using Cemusol NPT-12 as a detergent for cell lysis instead of Nonidet P-40 used for most RNA preparations.

Cell Nucleus↗
PubMed1976

Isolation and identification of the messenger ribonucleic acid for a structural lipoprotein of the Escherichia coli outer membrane.

The cells of Escherichia coli strain CP 78 were labeled with [32P]orthophosphate and the total radioactive RNA was prepared from the cells. The mRNA that codes for a structural lipoprotein in the outer membrane was purified from the total RNA by three successive electrophoreses on polyacrylamide slab gels, twice at pH 8.3 and once at pH 3.5 in 7 M urea. Approximately 0.002% of the total radioactive phosphate used was incorporated into the fraction containing the most purified mRNA. The two-dimensional fingerprint of the T1 ribonuclease digest of the 32P-labeled mRNA showed that the purity of the mRNA was as high as 90%. A preliminary sequence analysis was carried out on the T1 ribonuclease oligonucleotides which had been separated by the fingerprinting procedure. By using the established amino acid sequence of the lipoprotein and the genetic code, three relatively long oligonucleotides were assigned to code for three different parts of the lipoprotein. From these data, the present RNA fraction was identified as the lipoprotein mRNA. From the analysis of the T1 ribonuclease oligonucleotides, the mRNA was estimated to be 360 +/- 10 nucleotides in length. Although the length of the mRNA was enough to code for 2 lipoprotein molecules, T1 ribonuclease digestion of the mRNA yielded only 1 mol/mol of mRNA of the individual oligonucleotides assigned to parts of the amino acid sequence of the lipoprotein. This suggests that the mRNA codes for only 1 molecule of the lipoprotein. It was also found that the mRNA has no polyadenylate sequence at the 3' end.

Base Sequence↗
PubMed1976

Lipoprotein from the outer membrane of Escherichia coli: purification, paracrystallization, and some properties of its free form.

In the envelope of Escherichia coli, is a lipoprotein of molecular weight 7,200 as a major envelope protein. This lipoprotein was previously shown to exist in two different forms in the outer membrane of E. coli: the free form and the boundform, which is covalently linked to the peptidoglycau. The free form of the lipoprotein has been purified and paracrystallized by adding acetone to a sodium dodecyl sulfate solution in the presence of magnesium ion. The paracrystals were needle shaped. An electron micrograph of the negatively stained paracrystals showed a highly ordered ultrastructure. The chemical structure of the free form was compared with that of the bound form by (i) the amino acid composition, (ii) the fatty acid composition, and (iii) the peptide analysis after cyanogen bromide cleavage. The alpha-helical content of the free form of the lipoprotein was measured from the circular dichroism spectrum of the lipoprotein in 0.01% sodium dodecyl sulfate and found to be 87%. Using the purified lipoprotein as antigen, antiserum against the free form of the lipoprotein was obtained. Immunoprecipitation of the lipoprotein with the antiserum was found to be very specific, since only the free form of the lipoprotein was found as a major peak when the antiserum was reacted with the whole envelope proteins solubilized in 0.2% sodium dodecyl sulfate, and the immunoprecipitate thus formed was analyzed by polyacrylamide gel electrophoresis.

Amino Acids↗
PubMed1976

Protein synthesis in bacteriophage ghost-infected cells.

Escherichia coli B infected with T4 phage ghosts at 10 mM Mg2+ regains its protein synthesizing activity upon addition of ATP, GTP, and their generator to approximately 2% of the intact exponentially growing cells. In contrast to amino acid incorporation by intact cells, this system is sensitive to EDTA or low Mg2+. On the other hand, this system, differing from the regular cell-free system, does not respond to addition of soluble protein and ribonuclease. The ghost-infected cells were able to synthesize beta-galactosidase upon addition of the inducer isopropyl thiogalactoside. The initial rate of the induction was 2.6% of intact cells. For this induction, the addition of cyclic AMP, amino acids, ATP, GTP, UTP, CTP, and their generator was necessary. The induction of beta-galactosidase in these ghost-infected cells was very sensitive to the addition of EDTA, CaCl2, sulfhydryl blocking reagent, rifampin and chloramphenicol but insensitive to DNA synthesis inhibitors such as nalidixic acid and DNase.

Amino Acids↗
PubMed1975

Presence of active polyribosomes in bacterial cells infected with T4 bacteriophage ghosts.

Host protein synthesis of Escherichia coli stops abruptly after T4 bacteriophage ghost infection. When infection was carried out in the presence of 10 mM Mg2plus, infected cells still have active polyribosomes despite the complete stoppage of protein synthesis. On the other hand, when T4 ghost infection was carried out in the presence of 1 mM Mg2plus, no polyribosomes were observed and most of the ribosomes were 30S and 50S subunit particles. Subunits obtained from extracts of ghost-infected cells at 1 mM M'G2++ concentration could not be converted to polyribosomes, even when Mg2plus concentration was adjusted to 10 mM after ghost infection. There was very little difference in amino acid incorporation activities between polyribosomes from ghost-infected and uninfected cells. In addition, the activity of 70S ribosomes isolated from uninfected cells was identical to that from cells infected with ghosts at 10 mM Mg2plus.

Amino Acids↗