scholarly journals Stimulation of the processivity of the DNA polymerase of bacteriophage T4 by the polymerase accessory proteins. The role of ATP hydrolysis

1991 ◽  
Vol 266 (3) ◽  
pp. 1830-1840
Author(s):  
T C Jarvis ◽  
J W Newport ◽  
P H von Hippel
Keyword(s):  
Dna Polymerase ◽  
Atp Hydrolysis ◽  
Bacteriophage T4 ◽  
Accessory Proteins ◽  
Stimulation Of

Effect of temperature on transition and transversion mutagenesis: characterization of wild type and a mutator T4 DNA polymerase mutant

1984 ◽  
Vol 26 (3) ◽  
pp. 386-389 ◽  
Author(s):  
Linda J. Reha-Krantz ◽  
Sükran Parmaksizoglu
Keyword(s):  
Dna Polymerase ◽  
Low Temperatures ◽  
Bacteriophage T4 ◽  
Effect Of Temperature ◽  
In Vitro Mutagenesis ◽  
Wild Type ◽  
Mutational Site

The effect of temperature on genetically well-defined mutational pathways was examined in the bacteriophage T4. The mutational site was a T4 rII ochre mutant which could revert to rII+ via a transversion or to the amber convertant via a transition. Temperature did not strongly affect any of the pathways examined in a wild-type background; however, increased temperature reduced the mutational activity of a mutator DNA polymerase mutant. Possible models to explain the role of temperature in mutagenesis are discussed as well as the significance of low temperatures for in vitro mutagenesis reactions.Key words: bacteriophage T4, mutator, transition, transversion, temperature effects.

scholarly journals Accessory proteins assist exonuclease-deficient bacteriophage T4 DNA polymerase in replicating past an abasic site

2007 ◽  
Vol 402 (2) ◽  
pp. 321-329 ◽  
Author(s):  
Giuseppina Blanca ◽  
Emmanuelle Delagoutte ◽  
Nicolas Tanguy le gac ◽  
Neil P. Johnson ◽  
Giuseppe Baldacci ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Synthesis ◽  
Dna Polymerase ◽  
Bacteriophage T4 ◽  
Dna Polymerases ◽  
Accessory Proteins ◽  
Clamp Loader ◽  
Abasic Site ◽  
Translesion Dna Synthesis ◽  
Translesion Dna

Replicative DNA polymerases, such as T4 polymerase, possess both elongation and 3′–5′ exonuclease proofreading catalytic activities. They arrest at the base preceding DNA damage on the coding DNA strand and specialized DNA polymerases have evolved to replicate across the lesion by a process known as TLS (translesion DNA synthesis). TLS is considered to take place in two steps that often require different enzymes, insertion of a nucleotide opposite the damaged template base followed by extension from the inserted nucleotide. We and others have observed that inactivation of the 3′–5′ exonuclease function of T4 polymerase enables TLS across a single site-specific abasic [AP (apurinic/apyrimidinic)] lesion. In the present study we report a role for auxiliary replicative factors in this reaction. When replication is performed with a large excess of DNA template over DNA polymerase in the absence of auxiliary factors, the exo− polymerase (T4 DNA polymerase deficient in the 3′–5′ exonuclease activity) inserts one nucleotide opposite the AP site but does not extend past the lesion. Addition of the clamp processivity factor and the clamp loader complex restores primer extension across an AP lesion on a circular AP-containing DNA substrate by the exo− polymerase, but has no effect on the wild-type enzyme. Hence T4 DNA polymerase exhibits a variety of responses to DNA damage. It can behave as a replicative polymerase or (in the absence of proofreading activity) as a specialized DNA polymerase and carry out TLS. As a specialized polymerase it can function either as an inserter or (with the help of accessory proteins) as an extender. The capacity to separate these distinct functions in a single DNA polymerase provides insight into the biochemical requirements for translesion DNA synthesis.

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