Initiation of DNA Replication from Closed Circular DNA

Simmons, Daniel T.

doi:10.5772/20429

Cited by 2 publications

(5 citation statements)

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“…Another cellular component of the replication machine is topo I [ 1 , 2 ]. There are two binding sites on T antigen for topo I, near the C-terminal end and at the junction between the OBD and the J domain [ 36 , 37 ].…”

Section: Resultsmentioning

confidence: 99%

“…There is little structural information on pol/prim. This four subunit enzyme complex synthesizes the RNA primer using its p48 primase subunit and extends it with DNA using its p180 polymerase subunit [ 1 , 2 ]. Each of these two subunits would have to accommodate the passing ssDNA template in order to copy it.…”

Section: Resultsmentioning

confidence: 99%

“…It has been clearly documented that the SV40 large T antigen forms a structure that acts as a scaffold for the construction of the viral replication factory [ 1 , 2 , 3 ]. This virally encoded protein forms a double hexamer structure over the virus origin of replication [ 4 ].…”

Section: Introductionmentioning

confidence: 99%

“…Replication of the viral DNA is, however, dependent on a number of cellular proteins that are recruited to this unwinding machine. Three cellular proteins, replication protein A (RPA), topoisomerase I (topo I) and DNA polymerase alpha/primase (pol/prim) are needed for maximal replication initiation [ 1 , 2 , 3 ]. At least three other proteins, polymerase delta, PCNA and replication factor C (RFC) are required for elongation synthesis [ 1 , 2 , 3 ].…”

Section: Introductionmentioning

confidence: 99%

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Modeling of the SV40 DNA Replication Machine

Simmons

2012

Genes

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The mechanism of SV40 DNA replication is certainly not completely understood. The proteins that are necessary for replication have been known for quite some time, but how they work together to form a nanomachine capable of faithfully replicating the virus DNA is only partially understood. Some of the proteins involved have been crystallized and their 3D structures determined, and several EM reconstructions of SV40 T antigen have been generated. In addition, there is a fair amount of biochemical data that pinpoints the sites of interaction between various proteins. With this information, various models were assembled that show how the SV40 DNA replication nanomachine could be structured in three dimensional space. This process was aided by the use of a 3D docking program as well as fitting of structures. The advantage of the availability of these models is that they are experimentally testable and they provide an insight into how the replication machine could work. Another advantage is that it is possible to quickly compare newly published structures to the models in order to come up with improved models.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Modeling of the SV40 DNA Replication Machine

Simmons

2012

Genes

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“…Many helicases are also modular and, as well as a catalytic helicase core, they contain accessory modules that contribute to functional diversity. For example, the human Werner syndrome helicase has nuclease and strand-annealing domains required for its genome stabilizing function (17), while the replicative DNA helicases of the small DNA tumour viruses such as SV40 and papillomavirus are fused to dsDNA-replication-origin–binding domains that allow them to function in replication initiation (18). …”

Section: Introductionmentioning

confidence: 99%

Characterization of an unusual bipolar helicase encoded by bacteriophage T5

Wong

Sayers

Sanders

2013

Nucleic Acids Research

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Bacteriophage T5 has a 120 kb double-stranded linear DNA genome encoding most of the genes required for its own replication. This lytic bacteriophage has a burst size of ∼500 new phage particles per infected cell, demonstrating that it is able to turn each infected bacterium into a highly efficient DNA manufacturing machine. To begin to understand DNA replication in this prodigious bacteriophage, we have characterized a putative helicase encoded by gene D2. We show that bacteriophage T5 D2 protein is the first viral helicase to be described with bipolar DNA unwinding activities that require the same core catalytic residues for unwinding in either direction. However, unwinding of partially single- and double-stranded DNA test substrates in the 3′–5′ direction is more robust and can be distinguished from the 5′–3′ activity by a number of features including helicase complex stability, salt sensitivity and the length of single-stranded DNA overhang required for initiation of helicase action. The presence of D2 in an early gene cluster, the identification of a putative helix-turn-helix DNA-binding motif outside the helicase core and homology with known eukaryotic and prokaryotic replication initiators suggest an involvement for this unusual helicase in DNA replication initiation.

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Initiation of DNA Replication from Closed Circular DNA

Cited by 2 publications

References 91 publications

Modeling of the SV40 DNA Replication Machine

Modeling of the SV40 DNA Replication Machine

Characterization of an unusual bipolar helicase encoded by bacteriophage T5

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