PROSITE documentation PDOC00834
Radical activating enzymes signature


In Escherichia coli and related bacteria, the pflA protein (or act) [1] is involved (EC in the activation of pyruvate formate-lyase (gene pflB) under anaerobic conditions by generation of an organic free radical, using S-adenosylmethionine and reduced flavodoxin as cosubstrates to produce 5'-deoxy-adenosine. A protein highly similar to pflA and termed pflC [2] is probably involved in the activation of a second pyruvate format lyase (gene pflD). The pflA/C proteins belong to a family that also includes phage T4 and Escherichia coli nrdG which are involved [3] in the generation of the free radical for the anaerobic ribonucleoside-triphosphate reductase (gene nrdD or sunY). This family also includes:

  • Escherichia coli hypothetical protein yjjW.
  • Haemophilus influenzae hypothetical protein HI0520.
  • Methanococcus jannaschii hypothetical protein MJ0021.

All these proteins possess, in their N-terminal section, a highly conserved region which contains three clustered cysteines which are involved in the binding of a 4Fe4S iron-sulfur cluster [4]. We use this region as a signature pattern.

Last update:

December 2004 / Pattern and text revised.


Technical section

PROSITE method (with tools and information) covered by this documentation:

RADICAL_ACTIVATING, PS01087; Radical activating enzymes signature  (PATTERN)


1AuthorsRoedel W. Plaga W. Frank R. Knappe J.
SourceEur. J. Biochem. 177:153-158(1988).

2AuthorsReizer J. Reizer A. Saier M.H. Jr.
TitleNovel phosphotransferase system genes revealed by bacterial genome analysis--a gene cluster encoding a unique Enzyme I and the proteins of a fructose-like permease system.
SourceMicrobiology 141:961-971(1995).
PubMed ID7773398

3AuthorsSun X. Eliasson R. Pontis E. Andersson J. Buist G. Sjoeberg B.-M. Reichard P.
TitleGeneration of the glycyl radical of the anaerobic Escherichia coli ribonucleotide reductase requires a specific activating enzyme.
SourceJ. Biol. Chem. 270:2443-2446(1995).
PubMed ID7852304

4AuthorsTamarit J. Gerez C. Meier C. Mulliez E. Trautwein A. Fontecave M.
TitleThe activating component of the anaerobic ribonucleotide reductase from Escherichia coli. An iron-sulfur center with only three cysteines.
SourceJ. Biol. Chem. 275:15669-15675(2000).
PubMed ID10821845

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