Characterization of the major formamidopyrimidine-DNA glycosylase homolog in Mycobacterium tuberculosis and its linkage to variable tandem repeats

FEMS Immunol Med Microbiol. 2009 Jul;56(2):151-61. doi: 10.1111/j.1574-695X.2009.00562.x. Epub 2009 Jun 3.


The ability to repair DNA damage is likely to play an important role in the survival of facultative intracellular parasites because they are exposed to high levels of reactive oxygen species and nitrogen intermediates inside phagocytes. Correcting oxidative damage in purines and pyrimidines is the primary function of the enzymes formamidopyrimidine (faPy)-DNA glycosylase (Fpg) and endonuclease VIII (Nei) of the base excision repair pathway, respectively. Four gene homologs, belonging to the fpg/nei family, have been identified in Mycobacterium tuberculosis H37Rv. The recombinant protein encoded by M. tuberculosis Rv2924c, termed Mtb-Fpg1, was overexpressed, purified and biochemically characterized. The enzyme removed faPy and 5-hydroxycytosine lesions, as well as 8-oxo-7,8-dihydroguanine (8oxoG) opposite to C, T and G. Mtb-Fpg1 thus exhibited substrate specificities typical for Fpg enzymes. Although Mtb-fpg1 showed nearly complete nucleotide sequence conservation in 32 M. tuberculosis isolates, the region upstream of Mtb-fpg1 in these strains contained tandem repeat motifs of variable length. A relationship between repeat length and Mtb-fpg1 expression level was demonstrated in M. tuberculosis strains, indicating that an increased length of the tandem repeats positively influenced the expression levels of Mtb-fpg1. This is the first example of such a tandem repeat region of variable length being linked to the expression level of a bacterial gene.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / genetics
  • Bacterial Proteins / isolation & purification
  • Bacterial Proteins / metabolism*
  • Conserved Sequence
  • DNA Repair*
  • DNA, Bacterial / metabolism*
  • DNA-Formamidopyrimidine Glycosylase / genetics
  • DNA-Formamidopyrimidine Glycosylase / isolation & purification
  • DNA-Formamidopyrimidine Glycosylase / metabolism*
  • Gene Expression
  • Gene Expression Profiling
  • Humans
  • Minisatellite Repeats*
  • Mycobacterium tuberculosis / enzymology*
  • Mycobacterium tuberculosis / genetics
  • Mycobacterium tuberculosis / physiology*
  • Sequence Homology
  • Substrate Specificity


  • Bacterial Proteins
  • DNA, Bacterial
  • DNA-Formamidopyrimidine Glycosylase