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Biomedical subjects

R Okazaki

Publications and source records attributed to R Okazaki.

At least 91 records · Page 5Linked to original sources
PubMed1973

RNA-linked DNA fragments in vitro.

RNA-linked DNA fragments are intermediates in DNA replication in Escherichia coli cells made permeable to nucleoside triphosphates by treatment with toluene. Covalent linkage of a short RNA stretch to the 5' end of the DNA is proved by transfer of (32)P from [alpha-(32)P]dNTP to ribonucleotides upon digestion with alkali or pancreatic RNase, and by a small decrease in the molecular size upon alkaline hydrolysis. The (32)P transfer experiments reveal a unique structure...p(rPy)p(rA)p(rU or rC)p(dC)p... at the RNA-DNA junction.

Adenosine Triphosphate↗
PubMed1972

RNA-linked nascent DNA fragments in Escherichia coli.

Nucleic acid that is extracted from E. coli labeled by a brief pulse of [(3)H]dT and depatured by treatment with heat, formamide, or formaldehyde bands in a region with a density higher than that of single-stranded E. coli DNA in a Cs(2)SO(4) equilibrium density gradient. If treated with alkali or RNase, it then exhibits the density of single-stranded DNA. These results suggest the presence of a short strand of RNA covalently linked to the nascent DNA. Evidence for the presence of covalently linked RNA-DNA molecules is also obtained by pulse labeling with [(3)H]U. Analyses of nascent nucleic acids from cells pulse labeled for various times, and of the molecules with different sizes, support the hypothesis that the short DNA fragments are formed by extension of even shorter RNA chains, which are synthesized on the parental DNA strands and are removed before ligation of the DNA fragments. The synthesis of the RNA segment of the RNA-DNA molecule is much less sensitive to rifampicin than is the synthesis of bulk RNA.

Carbon Isotopes↗
PubMed1971

Slow joining of newly replicated DNA chains in DNA polymerase I-deficient Escherichia coli mutants.

In Escherichia coli mutants deficient in DNA polymerase I, newly replicated short DNA is joined at about 10% of the rate in the wild-type strains. It is postulated that DNA polymerase I normally functions in filling gaps between the nascent short segments synthesized by the replication complex. Possible implications of the finding are discussed in relation to other abnormal properties of these mutants.

Binding Sites↗
PubMed1969

Mechanism of DNA chain growth. 3. Equal annealing of T4 nascent short DNA chains with the separated complementary strands of the phage DNA.

Nascent short DNA chains isolated from T4-infected E. coli under a variety of conditions anneal equally to the separated complementary phage DNA strands. The samples examined include: pulse-labeled short chains isolated by alkaline sucrose gradient sedimentation from the T4D (wild type)-infected cells in both the early and late stages of phage DNA synthesis; nascent chains accumulated during ligase inhibition of T4 ts B20-infected cells; and the single-stranded nascent short chains isolated from T4D-infected cells by mild procedures involving no denaturation treatment. The results are consistent with the hypothesis that both strands of DNA are synthesized discontinuously.

Carbon Isotopes↗
PubMed1969

Mechanism of DNA chain growth. IV. Direction of synthesis of T4 short DNA chains as revealed by exonucleolytic degradation.

T4 nascent short chains labeled at their growing ends with H(3)-thymidine and uniformly with C(14)-thymidine were prepared, separated into complementary strands, and degraded by E. coli exonuclease I in the 3' to 5' direction or by B. subtilis nuclease in the 5' to 3' direction. The kinetics of release of H(3) and C(14) labels by both enzymes was consistent with the conclusion that the H(3) label is at the 3' end of the nascent short chains of both strands and that the short chains are products of discontinuous synthesis in the 5' to 3' direction along the two template strands.

Bacillus subtilis↗