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A glycyl radical solution: oxygen-dependent interconversion of pyruvate formate-lyase
- Source :
- Molecular microbiology. 29(4)
- Publication Year :
- 1998
-
Abstract
- Pyruvate formate-lyase (PFL) catalyses the non-oxidative dissimilation of pyruvate to formate and acetyl-CoA using a radical-chemical mechanism. The enzyme is enzymically interconverted between inactive and active forms, the active form contains an organic free radical located on a glycyl residue in the C-terminal portion of the polypeptide chain. Introduction of the radical into PFL only occurs anaerobically, and the activating enzyme responsible is an iron-sulphur protein that uses S-adenosyl methionine as cofactor and reduced flavodoxin as reductant. As the radical form of PFL is inactivated by molecular oxygen it is safeguarded during the transition to aerobiosis by conversion back to the radical-free, oxygen-stable form. This reaction is catalysed by the anaerobically induced multimeric enzyme alcohol dehydrogenase. The genes encoding PFL and its activating enzyme are adjacent on the chromosome but form discrete transcriptional units. This genetic organization is highly conserved in many, but not all, organisms that have PFL. Recent studies have shown that proteins exhibiting significant similarity to PFL and its activating enzyme are relatively widespread in facultative and obligate anaerobic eubacteria, as well as archaea. The physiological function of many of these PFL-like enzymes remains to be established. It is becoming increasingly apparent that glycyl radical enzymes are more prevalent than previously surmised. They represent a class of enzymes with unusual biochemistry and probably predate the appearance of molecular oxygen.
- Subjects :
- Free Radicals
Flavodoxin
Molecular Sequence Data
Microbiology
Cofactor
chemistry.chemical_compound
Residue (chemistry)
Bacterial Proteins
Acetyltransferases
Catalytic Domain
Escherichia coli
Formate
Amino Acid Sequence
Molecular Biology
Phylogeny
Alcohol dehydrogenase
chemistry.chemical_classification
Methionine
biology
Bacteria
Sequence Homology, Amino Acid
Amino acid
Oxygen
Enzyme
chemistry
Biochemistry
Genes, Bacterial
biology.protein
Trans-Activators
Subjects
Details
- ISSN :
- 0950382X
- Volume :
- 29
- Issue :
- 4
- Database :
- OpenAIRE
- Journal :
- Molecular microbiology
- Accession number :
- edsair.doi.dedup.....dc586c5a40bf2792ae74c43724d6524a