The Function of T4 DNA Polymerase

Speyer, Joseph F.; Rosenberg, David H.

doi:10.1101/sqb.1968.033.01.040

Cited by 32 publications

(9 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Other studies, for example, suggest that the products of T4 genes 43, 32, and 45 play roles in the repair of gaps which seem to be generated when phage DNA is replicated in the absence of the T4 gene 30 DNA ligase (31). This repair by the gene 43 polymerase is probably specific to replication since the enzyme does not appear to have a role either in recombination or in repair of UV-irradiated T4 DNA in vivo (53).…”

Section: Discussionmentioning

confidence: 99%

Suppression of Amber Mutations of Bacteriophage T4 Gene 43 (DNA Polymerase) by Translational Ambiguity

Karam

O’Donnell

1973

J Virol

View full text Add to dashboard Cite

The growth properties of twelve different amber (am) mutants of bacteriophage T4 gene 43 (DNA polymerase) were examined by using nonpermissive (su-) as well as permissive (su+) Escherichia coli hosts. It was found that most of these mutants were measurably suppressed in su-hosts by translational ambiguity (misreading of codons during protein synthesis). The ability of these mutants to grow in response to this form of weak suppression probably means that the T4 gene 43 DNA polymerase can be effective in supporting productive DNA replication when it is supplied in small amounts. By similar criteria, studies with other phage mutants suggested that the products of T4 genes 62 (uncharacterized), 44 (uncharacterized), 42 (dCMP-hydroxymethylase), and 56 (dCTPase) are also effective in small amounts. Some T4 gene products, such as the product of gene 41 (uncharacterized), seem to be partially dispensable for phage growth since am mutants of such genes do propagate, although weakly, in streptomycinresistant su-hosts which appear to have lost the capacity to suppress am mutations by ambiguity.

show abstract

Section: Discussionmentioning

confidence: 99%

Suppression of Amber Mutations of Bacteriophage T4 Gene 43 (DNA Polymerase) by Translational Ambiguity

Karam

O’Donnell

1973

J Virol

View full text Add to dashboard Cite

show abstract

“…1) has been observed with all the ligase-rIl double mutants which we have tested, including cases where rII deletions were used. Thus, the early slow DNA synthetic activity is independent of the quality of the mutated rII gene product as is probably caused by the gene 30 ligase deficiency.…”

Section: Resultsmentioning

confidence: 99%

“…(2 min) was used here to compensate, in part, for the difference in the rates of DNA synthesis during early and late times after infection. Figure 3 shows that DNA made at later times after infection in the absence of the gene 30 ligase (amH39X/ rUV375/tsL56) was more susceptible to breakdown than DNA made by the phage carrying a normal gene 30 (rUV375/tsL56). This means that phage DNA replication is affected by the gene 30 ligase deficiency throughout the phage growth cycle and that the transition from slow to rapid synthesis is probably not a reflection of increased DNA repair activity during late times after infection.…”

Section: Resultsmentioning

confidence: 99%

Properties of Bacteriophage T4 Mutants Defective in Gene 30 (Deoxyribonucleic Acid Ligase) and the rII Gene

Karam

Barker

1971

J Virol

View full text Add to dashboard Cite

In Escherichia coli K-12 strains infected with phage T4 which is defective in gene 30 [deoxyribonucleic acid (DNA) ligase] and in the rII gene (product unknown), near normal levels of DNA and viable phage were produced. Growth of such T4 ligase-rIl double mutants was less efficient in E. coli B strains which show the "rapidlysis" phenotype of rII mutations. In pulse-chase experiments coupled with temperature shifts and with inhibition of DNA synthesis, it was observed that DNA synthesized by gene 30-defective phage is more susceptible to breakdown in vivo when the phage is carrying a wild-type rII gene. Breakdown was delayed or inhibited by continued DNA synthesis. Mutations of the rII gene decreased but did not completely abolish the breakdown. T4 ligase-rII double mutants had normal sensitivity to ultraviolet irradiation.

show abstract

“…It is known that T4 phage codes for its own DNA polymerase (2). It is also known that the chief function of this polymerase is replication rather than repair or recombination (33). In addition, about a dozen other T4 gene products are also required for DNA replication; the function of only half of these is known (17).…”

Section: Fig 1 Sucrose Gradient Centrifugation Of T4 Phagementioning

confidence: 99%