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Biomedical subjects

T Komano

Publications and source records attributed to T Komano.

197 records · Page 11Linked to original sources
PubMed1975

Bacteriophage phi X174 DNA synthesis in Escherichia coli HF4704S (dnaHts) cells.

The DNA synthesis of bacteriophage phiX174 in Escherichia coli HF470S, a mutant temperature sensitive in the initiation of DNA replication (dnaHts), has been examined. In HF4704S cells, phiX174 can grow normally at 27 degree C whereas the phage cannot grow after the cessation of DNA synthesis of the host cells at 42 degrees C. Upon infection, phiX174 DNA can be injected into the host cell and the parental replicative form can be formed, but the progency replicative form cannot be synthesized at 43 degrees C in the absence of host DNA synthesis. The progency replicative form cannot be synthesized at 27 degrees C in the presence of 30 mug chloramphenicol/ml in the host cell which has been incubated for 74 min at 43 degrees C followed by transfer to 27 degrees C in the presence of 30 mug chloramphenicol/ml. When 30 mug chloramphenicol/ml is added later than 5 min after the temperature shift-down to 27 degrees C, the progency replicative form synthesis is not inhibited. Thus, the host cell function, for which the gene dnaH is responsible, has been shown to be essential to the progency replicative form production.

Chloramphenicol↗
PubMed1975

Deoxyribonucleic acid synthesis induced with ultraviolet light in Brij 58-treated Bacillus subtilis spores germinated in the presence of chloramphenicol.

The direct measurement of ultraviolet light-stimulated DNA synthesis in the permeable Bacillus subtilis cells was performed. Bacillus subtilis spores germinated in the presence of chloramphenicol were treated with Brij 58 and irradiated with ultraviolet light, and (3H)dTTP was incorporated into these cells by the DNA polymerase assay system. Characteristics of the incorporation were distinct from those into spores germinated in the absence of chloramphenicol and treated with Brij 58, in the respect that the former incorporation did not require ATP and only partially depended on the presence of all four deoxyribonucleoside triphosphates. The incorporation of (3H)dTTP into DNA was confirmed by CsCl density gradient centrifugation. A DNA polymerase I-deficient strain, JBl 49(59) had no (3H)sTTP incorporating activity induced by ultraviolet light irradiation when the germinated spores were treated with Brij 58. Analysis of alkaline sucrose gradient centrifugation revealed that fragmented DNA caused by ultraviolet light irradiation was rejoined to the size of DNA of non-irradiated cells by incubating irradiated cells in the DNA polymerase assay mixture containing NAD+. The results also suggested that a machinery of DNA repair probably pre-existed in the spore.

Bacillus subtilis↗
PubMed1975

Studies on pig serum lipoproteins. I. Separation and properties of low-density lipoproteins.

The low-density lipoproteins in pig serum were separated into two subclasses (LDL1 and LDL2) by 2 to 7% pore size gradient gel electrophoresis. Preparative gel electrophoresis in 2 to 4% gradient gel made it possible to isolate these components as distinct entities. After delipidation by chromatography on Sepharose 4B in the presence of SDS, both apo-LDL1 and apo-LDL2 were found to have a molecular weight of 2.6X10(5). However, when these apoproteins were incubated in 10% sodium dodecyl sulfate, fragmentation occurred and the minimum fragment molecular weight was estimated to be 2.4X10(4). No essential difference was found in the amino acid compositions or fragmentation patterns of the apoproteins. However, the amounts of carbohydrates in the two apoproteins were different (7.09% in apo-LDL1 and 5.08% in apo-LDL2). The carbohydrate composition was 0.8% sialic acid, 2.38% N-acetyl-glucosamine, and 4.01% neutral sugars in apo-LDL1 and 0.5, 1.75, and 2.83% in apo-LDL2, respectively. In both apoproteins, mannose, galactose, and fucose were present in almost the same molar ratio of 4-5 : 2-3 : 1.

Amino Acids↗
PubMed1974

Replication of deoxyribonucleic acid in Escherichia coli C mutants temperature sensitive in the initiation of chromosome replication.

An Escherichia coli HF4704S mutant temperature sensitive in deoxyribonucleic acid (DNA) synthesis and different from any previously characterized mutant was isolated. The mutated gene in this strain was designated dnaH. The mutant could grow normally at 27 C but not at 43 C, and DNA synthesis continued for an hour at a decreasing rate and then ceased. After temperature shift-up, the increased amount of DNA was 40 to 50%. When the culture was incubated at 43 C for 70 min and then transferred to 27 C, DNA synthesis resumed after about 50 min, initiating synchronously at a fixed region on the bacterial chromosome. The initiation step in DNA replication sensitive to 30 mug of chloramphenicol per ml occurs synchronously before the resumption of DNA replication after the temperature shift-down, being completed about 30 min before the start of DNA replication. When the cells incubated at 27 C in the presence of 30 mug of chloramphenicol per ml after the temperature shift-down to 27 C were transferred to 43 C with simultaneous removal of the antibiotic, no resumption of DNA replication was observed. When the culture was returned to 43 C after being released from high-temperature inhibition at 30 min before the start of DNA replication, no recovery replication was observed; whereas at 20 min, the recovery of replication was observed. These results indicated that HF4704S was temperature sensitive in the initiation of DNA replication. Analysis of HF4704S, by an interrupted conjugation experiment, indicated that gene dnaH was located at about 64 min on the E. coli C linkage map. In E. coli S1814 (a K-12 derivative), which was a dnaH(ts) transductant from HF4704S (C strain) with phage P1, the mutated gene (dnaH) was demonstrated to be closely linked to the thyA marker by conjugation and P1 transduction experiments and to be distinct from genes dnaA through dnaG.

Chloramphenicol↗
PubMed1973

Increasing activity of germinating Bacillus subtilis spores to incorporate thymidine triphosphate into deoxyribonucleic acid after detergent treatment.

The incorporation of (3)H-labeled thymidine triphosphate ((3)H-dTTP) into deoxyribonucleic acid (DNA) of germinated and then Brij 58-treated Bacillus subtilis spores was measured to study DNA replication activity of cells. The dTTP incorporation rate was very low in dormant spores, gradually increased as germination proceeded, and reached a level of the vegetative cell activity approximately 4 hr after the start of germination. This is in contrast to the DNA polymerase activity in the cell extract which remained at the same level throughout the germination period. The increase of the dTTP incorporation activity was inhibited by chloramphenicol or phenethyl alcohol. When these inhibitors were added after germination had proceeded, the elevated dTTP incorporation activity gradually decreased. Permeability to dTTP of spores germinated in the presence of chloramphenicol and then treated with Brij 58 was confirmed by (i) (3)H-dTTP incorporation into the treated spores following either electron or ultraviolet irradiation and (ii) release of radioactivity from the treated spores containing radioactively labeled DNA after deoxyribonuclease I treatment.

Alcohols↗
PubMedDate not supplied

Functional analysis of the fic gene involved in regulation of cell division.

We have shown that cAMP may be a regulation factor in cell division of Escherichia coli (Utsumi et al., 1982, 1989). The fic (filamentation induced by cAMP) gene of this system found previously (Utsumi, et al., 1982) was analysed in this study. The open reading frame of the fic gene coded for 200 amino acids. The pabA (p-aminobenzoate synthase) gene was found downstream from the fic gene. The distance between the end of fic and the start of pabA was 31 base pairs. To deduce the function of Fic protein, the fic gene was destroyed by the kanamycin-resistant (Kmr) gene and the fic gene was shown to be essential for growth of E. coli. Such mutants required PAB (p-aminobenzoate) or folate for growth. These data suggested that the Fic protein is involved in the synthesis of PAB or folate and the fic gene could be part of a pab operon. In cells starved of them, cell division was inhibited. Addition of folate also repressed the filamentation induced by cAMP at 43 degrees C in the fic-1 mutant. These results would indicate that Fic protein and cAMP are involved in a new regulatory mechanism of cell division via folate metabolism. Furthermore, it is also shown that cell division could be controlled by coordination of cAMP, Fic and Fts proteins.

Amino Acid Sequence↗