The bacterial oxidation of picolinamide, a photolytic product of Diquat.
The pathway of oxidation of picolinamide (pyridine-2-carboxamide) by a Gram-negative rod has been elucidated. Under conditions of high pH, restricted aeration and high substrate concentration, whole cells released 2,5-dihydroxypyridine into culture supernatants. Sodium arsenite at 5mm caused whole cells to accumulate 6-hydroxypicolinate, and, at 1mm, pyruvate, in culture media. Whole cells oxidized picolinamide, picolinate, 6-hydroxypicolinate, maleamate and maleate without lag. Cell-free extracts converted picolinamide into picolinate, and hydroxylated picolinate to 6-hydroxypicolinate. The hydroxylase was particulate, but could be solubilized by ultrasonic treatment; it required NAD(+) for activity, and did not require molecular oxygen. 2,5-Dihydroxypyridine was converted into maleamate and formate by an oxygenase requiring GSH and Fe(2+). Maleamate was deamidated to maleate, and maleate isomerized to fumarate, by unsupplemented extracts.
D000577:Amides / Q000378:metabolism*; D001152:Arsenicals; D001419:Bacteria / Q000378:metabolism*; D002474:Cell-Free System; D003470:Culture Media; D004178:Diquat / Q000378:metabolism; D005561:Formates; D005650:Fumarates; D006863:Hydrogen-Ion Concentration; D007501:Iron; D008298:Maleates; D006899:Mixed Function Oxygenases; D009243:NAD; D010084:Oxidation-Reduction; D010105:Oxygenases; D010782:Photolysis; D010848:Picolinic Acids / Q000378:metabolism*; D011726:Pyridinium Compounds / Q000378:metabolism*; D011773:Pyruvates
D000577:Amides; D001152:Arsenicals; D003470:Culture Media; D005561:Formates; D005650:Fumarates; D008298:Maleates; D010848:Picolinic Acids; D011726:Pyridinium Compounds; D011773:Pyruvates; D009243:NAD; D004178:Diquat; D007501:Iron; D006899:Mixed Function Oxygenases; D010105:Oxygenases