Biomaterial Database

Contribution of 3' leads to 5' exonuclease activity of DNA polymerase III holoenzyme from Escherichia coli to specificity. 1983

A R Fersht, and J W Knill-Jones

The effects of deoxynucleoside monophosphates on the 3' leads to 5' exonuclease activity of DNA polymerase III holoenzyme have been correlated with their effects on the fidelity of DNA replication. In particular, dGMP inhibits the proofreading activity of the enzyme and decreases the fidelity in those cases where a "following nucleotide effect" is also noted. This is strong evidence for proofreading. However, the absence of the effects of proofreading inhibitors or following nucleotides need not be evidence against the occurrence of proofreading: a theoretical analysis shows that these effects may not be observed even though there is active proofreading. This is suggested to be the case with the phage T4 enzyme system. The proofreading activity of Pol III appears to be directed primarily towards removing purine x pyrimidine-mediated rather than purine x purine-mediated misincorporations. recA protein inhibits the proofreading activity of Pol III on synthetic templates containing mismatched 3' termini. This is paralleled by a decrease in the fidelity of DNA replication in vitro. The inhibition is increased in the presence of dGMP or dAMP but there is no further increase in the infidelity of replication. The presence of both dNMPs and recA protein does not enable Pol III to copy past pyrimidine photodimers.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D010584	Bacteriophage phi X 174	The type species of the genus MICROVIRUS. A prototype of the small virulent DNA coliphages, it is composed of a single strand of supercoiled circular DNA, which on infection, is converted to a double-stranded replicative form by a host enzyme.	Coliphage phi X 174,Enterobacteria phage phi X 174,Phage phi X 174,phi X 174 Phage,Phage phi X174
D011938	Rec A Recombinases	A family of recombinases initially identified in BACTERIA. They catalyze the ATP-driven exchange of DNA strands in GENETIC RECOMBINATION. The product of the reaction consists of a duplex and a displaced single-stranded loop, which has the shape of the letter D and is therefore called a D-loop structure.	Rec A Protein,RecA Protein,Recombinases, Rec A
D003854	Deoxyribonucleotides	A purine or pyrimidine base bonded to a DEOXYRIBOSE containing a bond to a phosphate group.	Deoxyribonucleotide
D004258	DNA Polymerase III	A DNA-dependent DNA polymerase characterized in E. coli and other lower organisms but may be present in higher organisms. Use also for a more complex form of DNA polymerase III designated as DNA polymerase III* or pol III* which is 15 times more active biologically than DNA polymerase I in the synthesis of DNA. This polymerase has both 3'-5' and 5'-3' exonuclease activities, is inhibited by sulfhydryl reagents, and has the same template-primer dependence as pol II.	DNA Polymerase delta,DNA-Dependent DNA Polymerase III,DNA Pol III,DNA Dependent DNA Polymerase III,Polymerase III, DNA,Polymerase delta, DNA
D004259	DNA-Directed DNA Polymerase	DNA-dependent DNA polymerases found in bacteria, animal and plant cells. During the replication process, these enzymes catalyze the addition of deoxyribonucleotide residues to the end of a DNA strand in the presence of DNA as template-primer. They also possess exonuclease activity and therefore function in DNA repair.	DNA Polymerase,DNA Polymerases,DNA-Dependent DNA Polymerases,DNA Polymerase N3,DNA Dependent DNA Polymerases,DNA Directed DNA Polymerase,DNA Polymerase, DNA-Directed,DNA Polymerases, DNA-Dependent,Polymerase N3, DNA,Polymerase, DNA,Polymerase, DNA-Directed DNA,Polymerases, DNA,Polymerases, DNA-Dependent DNA
D004260	DNA Repair	The removal of DNA LESIONS and/or restoration of intact DNA strands without BASE PAIR MISMATCHES, intrastrand or interstrand crosslinks, or discontinuities in the DNA sugar-phosphate backbones.	DNA Damage Response
D004261	DNA Replication	The process by which a DNA molecule is duplicated.	Autonomous Replication,Replication, Autonomous,Autonomous Replications,DNA Replications,Replication, DNA,Replications, Autonomous,Replications, DNA
D004926	Escherichia coli	A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.	Alkalescens-Dispar Group,Bacillus coli,Bacterium coli,Bacterium coli commune,Diffusely Adherent Escherichia coli,E coli,EAggEC,Enteroaggregative Escherichia coli,Enterococcus coli,Diffusely Adherent E. coli,Enteroaggregative E. coli,Enteroinvasive E. coli,Enteroinvasive Escherichia coli
D005090	Exodeoxyribonucleases	A family of enzymes that catalyze the exonucleolytic cleavage of DNA. It includes members of the class EC 3.1.11 that produce 5'-phosphomonoesters as cleavage products.	DNA Exonucleases,Exonucleases, DNA