T4 DNA topoisomerase: a new ATP-dependent enzyme essential for initiation of T4 bacteriophage DNA replication

  title={T4 DNA topoisomerase: a new ATP-dependent enzyme essential for initiation of T4 bacteriophage DNA replication},
  author={Leroy F. Liu and Chung‐Cheng Liu and Bruce Alberts},
A novel ATP-dependent DNA topoisomerase which makes reversible double-strand breaks in the DNA double helix has been purified to near homogeneity from T4 bacteriophage-infected Escherichia coli cells. Genetic data suggest that this activity is essential for initiating T4 DNA replication forks in vivo. 
Reverse gyrase—a topoisomerase which introduces positive superhelical turns into DNA
An enzyme which converts closed circular DNA into a positively supercoiled form is present in cellular extracts of Sulfolobus, an acidothermophilic archaebacterium, and is active only at temperatures > 55 °C, in the presence of ATP and Mg2+.
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DNA duplication is catalyzed by DNA polymerase III in cooperation with a number of associated replication proteins; the DNA elongation complex has been termed “replisome" in the expectation of an ordered structure carrying out an ordered sequence of reaction steps.
Microbial DNA topoisomerases and their inhibition by antibiotics
A brief outline of the supercoiled state of DNA in bacteria and to all microbial topoisomerases hitherto described is devoted to the discovery of a so‐called reverse gyrase.
The probabilities of supercoil removal and decatenation by yeast DNA topoisomerase II
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    Genes to cells : devoted to molecular & cellular mechanisms
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To deduce the molecular characteristics of these enzyme‐mediated reactions, the efficiencies of supercoil removal and decatenation by the yeast enzyme upon the addition of a nonhydrolysable ATP analogue were determined.
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A selection of the new themes that have been recently introduced into the already large body of topoisomerase research are discussed.
Superhelical DNA-dependent ATPase from calf thymus.
Structure and Mechanism of Eukaryotic Type IIA Topoisomerases
A wealth of biochemical and structural data on Top2 (topo II), the eukaryotic member of this topoisomerase family, as well as complementary studies on its bacterial counterparts (DNA gyrase and topo IV), has helped explain many essential features of this complex catalytic cycle.


Recent excitement in the DNA replication problem
It is now possible to reproduce most of the reactions involved in DNA replication using prokaryotic enzymes in vitro. Such systems have revealed that DNA replication is a complex process depending on
DNA gyrase: an enzyme that introduces superhelical turns into DNA.
Relaxed closed-circular DNA is converted to negatively supercoiled DNA by DNA gyrase by purified from Escherichia coli cells, and the final superhelix density of the DNA can be considerably greater than that found in intracellularly super coiled DNA.
Structure of the replicating DNA from bacteriophage T4.
At an early stage of replication, parental T4 DNA shows a loop structure often displaying two 3'-ended, single-stranded "whiskers", located in trans configuration at the branching-points, which suggests that the loop was growing in both directions.
Physical structure of the replication origin of bacteriophage lambda.
The nucleotide sequence of part of the replication region of wild-type bacteriophage lambda and of four mutants defective in the origin of DNA replication (ori-) has been determined and contains a number of unusual features.
Genetic structure of the replication origin of bacteriophage lambda.
A fragment of bacteriophage lambda DNA produced by the restriction endonuclease Eco RI and extending from the immunity region to a point inside gene O is found to have a fully functional origin of
Initiation of DNA synthesis in Escherichia coli.
PERSPECfIVES AND SUMMARY 999 DNA SYNTHESIS ON SINGLE-STRANDED CIRCULAR DNA 1001 Priming by RNA Polymerase 1002 Priming by dnaG Protein 1003 Priming by dnaG Protein in Conjunction with Other Proteins
Probing DNA replication mechanisms with the T4 bacteriophage in vitro system.
The goal of this work is to obtain a static picture of the architecture of a replication fork (including the arrangement of the multienzyme complex which functions there), as well as a dynamicpicture of the events that accompany D N A polymerization.
Novobiocin and coumermycin inhibit DNA supercoiling catalyzed by DNA gyrase.
It is concluded that DNA gyrase controls the supercoiling of DNA in E. coli.
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Purification of gene 41 protein of bacteriophage T4.