Formyl phosphate: a proposed intermediate in the reaction catalyzed by Escherichia coli PurT GAR transformylase.
The Escherichia coli purT encoded glycinamide ribonucleotide transformylase (GAR transformylase) serves as an alternate enzyme in the production of formyl GAR for use in de novo purine biosynthesis. This enzyme differs from the previously known purN encoded enzyme in size, sequence, and substrates; ATP and formate are required as opposed to formyl tetrahydrofolate. Kinetic studies of the wild-type PurT enzyme described here demonstrate that formyl phosphate behaves as a chemically and kinetically competent intermediate. The requirement for ATP and GAR in these reactions is consistent with previous steady-state kinetic results, which demonstrated that all substrates must be bound before catalysis. Kinetic characterization of a mutant, which releases formyl phosphate into solution, and positional isotope exchange studies also support the assignment of formyl phosphate as a plausible intermediate.
Marolewski
A E
AE
Department of Chemistry, The Pennsylvania State University, University Park 16802, USA.
Mattia
K M
KM
Warren
M S
MS
Benkovic
S J
SJ
D000217:Acyltransferases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D004926:Escherichia coli / Q000201:enzymology*; D029968:Escherichia coli Proteins; D005561:Formates / Q000378:metabolism; D019877:Hydroxymethyl and Formyl Transferases; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009943:Organophosphorus Compounds / Q000378:metabolism*; D051026:Phosphoribosylglycinamide Formyltransferase; D012265:Ribonucleotides / Q000378:metabolism; D016415:Sequence Alignment
D029968:Escherichia coli Proteins; D005561:Formates; D009943:Organophosphorus Compounds; D012265:Ribonucleotides; C030544:formic acid; C014978:glycineamide ribonucleotide; C053858:formyl phosphate; D000255:Adenosine Triphosphate; D019877:Hydroxymethyl and Formyl Transferases; C494825:purT protein, E coli; D051026:Phosphoribosylglycinamide Formyltransferase; D000217:Acyltransferases