Novel DNA repair alkyltransferase from Caenorhabditis elegans

S. Kanugula, Anthony Pegg, Larry Thompson, Jack Von Borstel

Research output: Contribution to journalArticle

21 Scopus citations

Abstract

O6-Alkylguanine DNA-alkyltransferase (AGT) is a widely distributed DNA repair protein that protects living organisms from endogenous and exogenous alkylation damage to DNA at the O6-position of guanine. The search of the C. elegans genome database for an AGT protein revealed the presence of a protein (cAGT-2) with some similarity to known AGTs in addition to the easily recognized cAGT-1 protein. The predicted protein sequence of cAGT-2 contains the amino acid sequence -ProCys-HisPro- at the presumed active site of the protein, whereas all other known AGTs have -ProCys-HisArg-. A truncated version of the cAGT-2 protein was expressed in E. coli. This purified recombinant protein was able to repair O6-methylguanine and O4-methylthymine adducts in DNA in vitro and also reacted with the bulky benzyl adduct in O6-benzylguanine. This fragment of cAGT-2 (104 amino acids) is the smallest protein possessing AGT activity yet described. The full-length cAGT-2 protein (274 amino acids) totally lacks the N-terminal domain present in all other known AGTs but has a long C-terminal extension that has significant homology to histone 1C. Expression of cAGT-2 in an E. coli strain lacking endogenous AGT activity provided modest but statistically significant resistance to the toxicity of N-methyl-N′-nitro-N-nitrosoguanidine, confirming that cAGT-2 is an alkyltransferase.

Original languageEnglish (US)
Pages (from-to)235-243
Number of pages9
JournalEnvironmental and Molecular Mutagenesis
Volume38
Issue number2-3
DOIs
StatePublished - Nov 28 2001

All Science Journal Classification (ASJC) codes

  • Environmental Science(all)
  • Environmental Chemistry
  • Genetics
  • Genetics(clinical)
  • Toxicology
  • Health, Toxicology and Mutagenesis

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