DNA polymerase lambda, a novel DNA repair enzyme in human cells.

Abstract:

DNA polymerase lambda (pol lambda) is a novel family X DNA polymerase that has been suggested to play a role in meiotic recombination and DNA repair. The recent demonstration of an intrinsic 5'-deoxyribose-5-phosphate lyase activity in pol lambda supports a function of this enzyme in base excision repair. However, the biochemical properties of the polymerization activity of this enzyme are still largely unknown. We have cloned and purified human pol lambda to homogeneity in a soluble and active form, and we present here a biochemical description of its polymerization features. In support of a role in DNA repair, pol lambda inserts nucleotides in a DNA template-dependent manner and is processive in small gaps containing a 5'-phosphate group. These properties, together with its nucleotide insertion fidelity parameters and lack of proofreading activity, indicate that pol lambda is a novel beta-like DNA polymerase. However, the high affinity of pol lambda for dNTPs (37-fold over pol beta) is consistent with its possible involvement in DNA transactions occurring under low cellular levels of dNTPs. This suggests that, despite their similarities, pol beta and pol lambda have nonredundant in vivo functions.

Polymerases:

Topics:

Historical Protein Properties (MW, pI, ...), Source / Purification, Exonuclease Activity, Kinetic Parameters, Fidelity, Nucleotide Incorporation

Status:

new topics/pols set partial results complete validated

Results:

Polymerase Reference Property Result Context
Human Pol lamba García-Díaz M2002 Molecular Weight 6.8E+04 Dalton Technique: SDS-PAGE
Human Pol lamba García-Díaz M2002 3-5' Exonuclease (proofreading) No
Human Pol lamba García-Díaz M2002 Cloned or native Cloned in E. coli
Human Pol lamba García-Díaz M2002 Nucleotide Substitution Rate 0.0009 errors/bp Technique: M13mp2 forward mutation assay
Human Pol lamba García-Díaz M2002 Full length or truncated Full length
Human Pol lamba García-Díaz M2002 Processivity 6bp
Human Pol lamba García-Díaz M2002 KM 0.5uM Reaction: Nucleotide incorporation; Substrate: dNTPs

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