Characterization of a natural mutator variant of human DNA polymerase lambda which promotes chromosomal instability by compromising NHEJ

PLoS One. 2009 Oct 6;4(10):e7290. doi: 10.1371/journal.pone.0007290.


Background: DNA polymerase lambda (Pollambda) is a DNA repair polymerase, which likely plays a role in base excision repair (BER) and in non-homologous end joining (NHEJ) of DNA double-strand breaks (DSB).

Principal findings: Here, we described a novel natural allelic variant of human Pollambda (hPollambda) characterized by a single nucleotide polymorphism (SNP), C/T variation in the first base of codon 438, resulting in the amino acid change Arg to Trp. In vitro enzyme activity assays of the purified W438 Pollambda variant revealed that it retained both DNA polymerization and deoxyribose phosphate (dRP) lyase activities, but had reduced base substitution fidelity. Ectopic expression of the W438 hPollambda variant in mammalian cells increases mutation frequency, affects the DSB repair NHEJ pathway, and generates chromosome aberrations. All these phenotypes are dependent upon the catalytic activity of the W438 hPollambda.

Conclusions: The expression of a cancer-related natural variant of one specialized DNA polymerase can be associated to generic instability at the cromosomal level, probably due a defective NHEJ. These results establish that chromosomal aberrations can result from mutations in specialized DNA repair polymerases.

Publication types

  • Research Support, N.I.H., Intramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acids / chemistry
  • Arginine / chemistry
  • Chromosomal Instability / genetics*
  • Chromosome Aberrations
  • Codon
  • DNA / chemistry
  • DNA Breaks, Double-Stranded
  • DNA Mutational Analysis
  • DNA Polymerase beta / genetics*
  • DNA Polymerase beta / physiology
  • DNA Repair
  • DNA Repair Enzymes / genetics*
  • DNA Repair Enzymes / metabolism
  • DNA-Binding Proteins / genetics*
  • DNA-Binding Proteins / metabolism
  • Humans
  • Mutation*
  • Polymorphism, Single Nucleotide
  • Tryptophan / chemistry


  • Amino Acids
  • Codon
  • DNA-Binding Proteins
  • NHEJ1 protein, human
  • Tryptophan
  • DNA
  • Arginine
  • DNA polymerase beta2
  • DNA Polymerase beta
  • DNA Repair Enzymes