Molybdenum cofactor-dependent resistance to N-hydroxylated base analogs in Escherichia coli is independent of MobA function

Mutat Res. 2007 Jun 1;619(1-2):9-15. doi: 10.1016/j.mrfmmm.2006.12.005. Epub 2007 Feb 2.


Lack of molybdenum cofactor (MoCo) in Escherichia coli and related microorganisms was found to cause hypersensitivity to certain N-hydroxylated base analogs, such as HAP (6-N-hydroxylaminopurine). This observation has lead to a previous proposal that E. coli contains a molybdoenzyme capable of detoxifying such N-hydroxylated analogs. Here, we show that, unexpectedly, deletion of all known or putative molybdoenzymes in E. coli failed to reveal any base-analog sensitivity, suggesting that a novel type of MoCo-dependent activity is involved. Further, we establish that protection against the analogs does not require the common molybdopterin guanine-dinucleotide (MGD) form of the cofactor, but instead the guanosine monophosphate (GMP)-free version of MoCo (MPT) is sufficient.

Publication types

  • Research Support, N.I.H., Intramural

MeSH terms

  • Adenine / analogs & derivatives*
  • Adenine / toxicity
  • Coenzymes / chemistry
  • Coenzymes / metabolism*
  • Drug Resistance, Bacterial / genetics
  • Escherichia coli / drug effects*
  • Escherichia coli / genetics
  • Escherichia coli / metabolism*
  • Escherichia coli Proteins / genetics
  • Escherichia coli Proteins / metabolism*
  • Genes, Bacterial
  • Metalloproteins / chemistry
  • Metalloproteins / metabolism*
  • Mutagens / toxicity
  • Pteridines / chemistry
  • Pteridines / metabolism*


  • Coenzymes
  • Escherichia coli Proteins
  • Metalloproteins
  • Mutagens
  • Pteridines
  • mobA protein, E coli
  • 6-N-hydroxylaminopurine
  • molybdenum cofactor
  • Adenine