Microbial metabolism of the pyridine ring. The metabolism of pyridine-3,4-diol (3,4-dihydroxypyridine) by Agrobacterium sp

Abstract

1. Pyridine-3,4-diol (3,4-dihydroxypyridine, 3-hydroxypyrid-4-one), an intermediate in 4-hydroxypyridine metabolism by an Agrobacterium sp (N.C.I.B. 10413), was converted by extracts into 1mol of pyruvate, 2mol of formate and 1mol of NH(3) at pH7.0. 2. Formate, but not the alternative likely product formamide, was further oxidized fivefold faster by 4-hydroxypyridine-grown washed cells than by similar organisms grown on succinate. 3. The oxidation of pyridine-3,4-diol by crude extracts at pH8.5 required 1mol of O(2)/mol of substrate, produced 1mol of acid and led to the formation of formate and a new compound with an extinction maximum of 285nm (Compound I). This step was believed to be mediated by a new labile dioxygenase (t((1/2))=4h at pH7.0, 4 degrees C) cleaving the pyridine ring between C-2 and C-3. 4. Many of the properties of this pyridine-3,4-diol dioxygenase paralleled those of the extradiol (;meta') oxygenases of aromatic-ring cleavage. The extreme lability of the enzyme has so far precluded extensive purification. 5. Compound I showed changes in the u.v.-absorption spectrum with pH but after acidification it was converted into a new product, 3-formylpyruvate, with an extinction maximum now at 279nm. 6. Both Compound I and 3-formylpyruvate were metabolized by extracts but at very different rates. The slower rate of metabolism of Compound I was nevertheless consistent with that of pyridine-3,4-diol metabolism. 7. On acidification Compound I released about 0.65mol of NH(3) and has been identified as 3-formiminopyruvate. 8. 3-Formylpyruvate was hydrolysed to formate and pyruvate (K(m) 2mum) by an acylpyruvate hydrolase active against several other dioxo homologues. The activity of this enzyme was much lower in extracts of succinate-grown cells.

Microbial Metabolism of Quinoline and Related Compounds. XIV. Purifk ation and Properties of 1H-3-Hydroxy-4-oxoquinoline Oxygenase, a New Extradiol Cleavage Enzyme fromPseudomonasputida Strain 33/1

“…In contrast to these enzymes, our enzyme is very stable and does not need to be stabilized by the addition of 10% acetone. Many of the bacterial meta-cleavage dioxygenases have a broad substrate specificity^9· 24 ' 26 · 33 ' 381 whereas the l//-3-hydroxy-4-oxoquinoline oxygenase possesses a narrow substrate range similar to the pyridine-3,4-diol dioxygenase^1 11 and two other multi-ring extradiol dioxygenases^1 0 · 221 . Hg 20 and 4-chloromercuribenzoate strongly inhibited the enzyme which suggests an involvement of sulfhydryl groups in the activity.…”

Microbial degradation of pyridine by Paracoccus sp. isolated from contaminated soil

“…Since 1910s, researchers have isolated some microbial organisms degrading pyridine and its derivatives including hydroxypyridine, alkylpyridine and carboxypyridine, and elucidated microbial metabolic pathway of these compounds [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. There were some examples as following.…”

“…There were some examples as following. A group leaded by Cain [1,2,5,[9][10][11][12] from U.K. obtained some pure cultures with the ability to utilize pyridine as sole source of carbon, nitrogen and energy, and its hydroxy derivatives as principal carbon source by elective culture either from sewage of an activated-sludge plant or a few crumbs of soil. Five pure strains were selected for detailed study.…”

Bacterial Degradation of Quinoline and Derivatives—Pathways and Their Biocatalysts

“…probably catalyzes an extradiol cleavage reaction, forming 3-(N-formyl)-formiminopyruvate, which upon hydrolysis would yield the observed products formate and 3-formiminopyruvate (Scheme 4c). [37] In an analogous reaction catalyzed by 2,5-dihydroxypyridine 5,6-dioxygenases from various strains (Scheme 4d), the hydrolysis products maleamate and formate were identified. [38] The latter enzymes require Fe 2 and a thiol donor such as dithiothreitol, cysteine, or glutathion for activity.…”