Deoxyribonucleoside triphosphate (dNTP) concentrations measured in cells are not symmetric. dGTP almost always represents only 5-10% of the total dNTP pools in cells. In an in vitro replication system involving semiconservative replication from an SV 40 origin, the mutation frequency of an M13 phagemid replicated by human cell extracts in...
Vaccinia virus-infected animal cells have been used to
study the interactions between the replication of
deoxyribonucleic acid (DNA) and the biosynthesis of its
nucleotide precursors. Some antimetabolites that inhibit
DNA replication have as their targets enzymes of nucleotide
biosynthesis. Furthermore, the disruption of nucleotide
metabolism can alter the fidelity of...
Ribonucleotide reductase is an important enzyme in the control of
DNA replication within the cell. Ribonucleotide reductase exerts its
control through enzymatic reduction of nucleoside diphosphates. The
bacteriophage T4 enzyme is an example of the class of iron-requiring
reductases which also includes E. coli and mammalian ribonucleotide
reductases. The two...
Bacteriophage T4 gene 42 encodes dCMP hydroxymethylase, an
enzyme unique to the deoxyribonucleotide metabolism of T-even
bacteriophages. To study biochemical and biophysical properties of
the enzyme, as well as the interaction of dCMP hydroxymethylase with
other DNA precursor biosynthetic enzymes in vitro, availability of large
amounts of the enzyme is...
Vaccinia virus infected monkey kidney cells had been previously shown
to have an increased ribonucleoside diphosphate reductase (RR) activity. DNA
from mutant virus resistant to hydroxyurea were digested with restriction
endonucleases and were shown to have substoichiometric amounts of the Hind
III F fragment. Additional information from Southern blotting experiments...
Although the synthesis of DNA precursors is
closely coordinated with DNA replication, it is still
not clear whether deoxyribonucleoside triphosphates
(dNTPs) influence DNA replication independently of
their interactions with DNA polymerase catalytic sites.
In an effort to understand the extent to which rate and
fidelity of DNA replication are regulated...
A rapid nuclear isolation technique was adapted in
order to examine the question of DNA precursor
compartmentation in mammalian cells. By using this method
a reproducible proportion of the cellular nucleotides
remained associated with the isolated nuclei.
Examination, at several different cell densities, of
exponentially growing HeLa cells showed that...
A crucial factor in determining the accuracy of DNA replication is
maintenance of a balanced supply of deoxyribonucleoside triphosphates
(dNTPs) at replication forks. Perturbation of dNTP biosynthesis can
induce dNTP pool imbalance with deleterious genetic consequences,
including increased mutagenesis, recombination, chromosomal
abnormalities and cell death. Using the T4 bacteriophage system,...
Imbalanced deoxyribonucleoside triphosphate (dNTP) pools are mutagenic for DNA synthesis in both intact cells and cell-free replication systems. Almost certainly, such mutagenesis involves competition between correctly and incorrectly base-paired precursors at replication sites. However, there are certain differences between the intact cell and cell-free systems that do not always allow...
The ability to faithfully replicate DNA is dependent upon the maintenance
and regulation of its precursors, the deoxyribonucleoside triphosphates.
Enzymes encoded by the bacteriophage T4 have been widely used as models
of biochemical processes. A body of evidence supports the concept that the
bacteriophage T4 enzymes involved in deoxyribonucleotide biosynthesis...