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The bacteriophage phi 29 DNA polymerase, a proofreading enzyme.
C Garmendia1, A Bernad, J A Esteban
1Centro de Biología Molecular (Consejo Superior de Investigacìones Científicas-UAM), Universidad Autónoma, Madrid, Spain.
The Journal of Biological Chemistry
|February 5, 1992
Summary
Bacteriophage phi 29 DNA polymerase proofreads DNA replication by excising mismatched nucleotides. This proofreading requires coupling polymerase and exonuclease activities to prevent errors during viral DNA synthesis.
Area of Science:
- Molecular Biology
- Virology
- Enzymology
Background:
- Bacteriophage phi 29 DNA polymerase is crucial for viral DNA replication initiation and elongation.
- The enzyme possesses significant 3',5'-exonuclease activity, particularly on single-stranded DNA.
Purpose of the Study:
- To investigate the proofreading capabilities of bacteriophage phi 29 DNA polymerase.
- To elucidate the role of its 3',5'-exonuclease activity in preventing DNA replication errors.
Main Methods:
- Comparative analysis of wild-type phi 29 DNA polymerase and a mutant lacking 3',5'-exonuclease activity.
- Characterization of exonuclease activity preference for mismatched versus correctly paired DNA termini.
Main Results:
- Phi 29 DNA polymerase exhibits high processivity in its 3',5'-exonuclease activity, preferring single-stranded DNA.
- The exonuclease activity preferentially excises mismatched 3' termini over correctly paired ones.
- Coupling of exonuclease and polymerase activities is essential for error prevention in DNA replication.
Conclusions:
- Bacteriophage phi 29 DNA polymerase functions as a proofreading enzyme.
- The editing mechanism of phi 29 DNA polymerase is similar to that of T4 DNA polymerase and E. coli DNA polymerase I.
- Effective proofreading relies on the coordinated action of polymerase and exonuclease functions.