Glyphosate catabolism by Pseudomonas sp. strain PG2982.
The pathway for the degradation of glyphosate (N-phosphonomethylglycine) by Pseudomonas sp. PG2982 has been determined by using metabolic radiolabeling experiments. Radiorespirometry experiments utilizing [3-14C]glyphosate revealed that approximately 50 to 59% of the C-3 carbon was oxidized to CO2. Fractionation of stationary-phase cells labeled with [3-14C]glyphosate revealed that from 45 to 47% of the assimilated label is distributed to proteins and that the amino acids methionine and serine are highly labeled. Adenine and guanine received 90% of the C-3 label found in the nucleic acid fraction, and the only pyrimidine base labeled was thymine. These results indicated that C-3 of glyphosate was at some point metabolized to a C-1 compound whose ultimate fate could be both oxidation to CO2 and distribution to amino acids and nucleic acid bases that receive a C-1 group from the C-1-donating coenzyme tetrahydrofolate. Pulse-labeling of PG2982 cells with [3-14C]glyphosate resulted in the isolation of [3-14C]sarcosine as an intermediate in glyphosate degradation. Examination of crude extracts prepared from PG2982 cells revealed the presence of a sarcosine-oxidizing enzyme that oxidizes sarcosine to glycine and formaldehyde. These results indicate that the first step in glyphosate degradation by PG2982 is cleavage of the carbon-phosphorus bond, resulting in the release of sarcosine and a phosphate group. The phosphate group is utilized as a source of phosphorus, and the sarcosine is degraded to glycine and formaldehyde. This pathway is supported by the results of [1,2-14C]glyphosate metabolism studies, which show that radioactivity in the proteins of labeled cells is found only in the glycine and serine residues.
D000225:Adenine / Q000378:metabolism; D001426:Bacterial Proteins / Q000378:metabolism; D005557:Formaldehyde / Q000378:metabolism; D005561:Formates / Q000378:metabolism; D005998:Glycine / Q000031:analogs & derivatives* / Q000378:metabolism; D006147:Guanine / Q000378:metabolism; D008715:Methionine / Q000378:metabolism; D010089:Oxidoreductases, N-Demethylating / Q000378:metabolism; D011549:Pseudomonas / Q000201:enzymology / Q000378:metabolism*; D012521:Sarcosine / Q000378:metabolism; D050879:Sarcosine Oxidase; D012694:Serine / Q000378:metabolism; D000097797:Glyphosate
D000225:Adenine; D001426:Bacterial Proteins; D005557:Formaldehyde; D005561:Formates; D005998:Glycine; D006147:Guanine; D008715:Methionine; D010089:Oxidoreductases, N-Demethylating; D012521:Sarcosine; D050879:Sarcosine Oxidase; D012694:Serine; D000097797:Glyphosate; C030544:formic acid