MetaCyc Enzyme: Pfl-activating enzyme

Gene: act Accession Number: G-9370 (MetaCyc)

Species: Clostridium pasteurianum

pyruvate formate-lyase (Pfl) catalyzes the reversible, coenzyme A-dependent, nonoxidative dissimilation of pyruvate to acetyl-coenzyme A and formate and forms the major route of pyruvate catabolism in anaerobically growing Escherichia coli K-12. The cleavage of the pyruvate C-C bond is catalyzed by an organic free radical which is located on a glycyl residue at amino acid position 734 on the polypeptide chain [Unkrig89, Wagner92]. The anaerobic introduction of the radical into the polypeptide chain is catalyzed by a 28-kDa iron-dependent Pfl-activating enzyme (Act) [Knappe90].

In contrast to the catabolic function of pyruvate formate-lyase in Escherichia coli K-12, Enterococcus faecalis, and Streptococcus mutans, the clostridial enzyme has an anabolic function in furnishing the cells with C1 units [Thauer72, Thauer70]. Initially Pfl could not be detected in Clostridium pasteurianum, but eventually Weidner and Sawers were able to clone the genes and demonstrate their activity [Weidner96].

Molecular Weight of Polypeptide: 27.148 kD (from nucleotide sequence), 28 kD (experimental) [Weidner96 ]

Unification Links: ModBase:Q46267 , Protein Model Portal:Q46267 , Swiss-Model:Q46267 , UniProt:Q46267

Relationship Links: Entrez-Nucleotide:PART-OF:X93463 , InterPro:IN-FAMILY:IPR001989 , InterPro:IN-FAMILY:IPR007197 , InterPro:IN-FAMILY:IPR012838 , Pfam:IN-FAMILY:PF04055 , Prosite:IN-FAMILY:PS01087

Gene-Reaction Schematic: ?

Gene-Reaction Schematic


Enzymatic reaction of: Pfl-activating enzyme

EC Number:

a [formate C acetyltransferase]-glycine + S-adenosyl-L-methionine + a reduced flavodoxin <=> a [formate C acetyltransferase]-glycin -2-yl radical + 5'-deoxyadenosine + L-methionine + a flavodoxin semiquinone

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the Enzyme Commission system.

Reversibility of this reaction is unspecified.


Knappe90: Knappe J, Sawers G (1990). "A radical-chemical route to acetyl-CoA: the anaerobically induced pyruvate formate-lyase system of Escherichia coli." FEMS Microbiol Rev 1990;6(4);383-98. PMID: 2248795

Thauer70: Thauer RK, Rupprecht E, Jungermann K (1970). "The synthesis of one-carbon units from CO(2) via a new ferredoxin dependent monocarboxylic acid cycle." FEBS Lett 8(5);304-307. PMID: 11947600

Thauer72: Thauer RK, Kirchniawy FH, Jungermann KA (1972). "Properties and function of the pyruvate-formate-lyase reaction in clostridiae." Eur J Biochem 27(2);282-90. PMID: 4340563

Unkrig89: Unkrig V, Neugebauer FA, Knappe J (1989). "The free radical of pyruvate formate-lyase. Characterization by EPR spectroscopy and involvement in catalysis as studied with the substrate-analogue hypophosphite." Eur J Biochem 184(3);723-8. PMID: 2553398

Wagner92: Wagner AF, Frey M, Neugebauer FA, Schafer W, Knappe J (1992). "The free radical in pyruvate formate-lyase is located on glycine-734." Proc Natl Acad Sci U S A 1992;89(3);996-1000. PMID: 1310545

Weidner96: Weidner G, Sawers G (1996). "Molecular characterization of the genes encoding pyruvate formate-lyase and its activating enzyme of Clostridium pasteurianum." J Bacteriol 178(8);2440-4. PMID: 8636053

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Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
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