Vanillate monooxygenase

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Vanillate monooxygenase
Cofactor NAD (P) + , [2Fe2S]
Identifier
Gene name (s) vanA , vanB
External IDs
Enzyme classification
EC, category 1.14.13.82 ,  monooxygenase
Substrate Vanillic acid, O 2 , NAD (P) H + H +
Products Protocatechuic acid, H 2 O, formaldehyde, NAD (P) +
Occurrence
Parent taxon bacteria

The vanillate monooxygenase (VAN, EC  1.14.13.82 ), also called vanillate demethylase referred catalyzes the conversion of vanillate, the anion of vanillic acid to protocatechuic acid . NADH is oxidized to NAD + , but depending on the species, NADPH can also act as an electron donor. As a monooxygenase , the enzyme consumes oxygen (O 2 ), forming formaldehyde and water:

Vanillic acid+ O 2 + NAD (P) H + H + + NAD (P) + + H 2 O + CH 2 O Protocatechuic acid

VAN has been identified in Pseudomonas , Acinetobacter and Corynebacterium strains.

Vanillate monooxygenase is a heterodimeric enzyme and is composed of an oxygenase and an oxidoreductase subunit. The former is encoded by the vanA gene, the latter by the vanB gene; they are close homologues. VanB also has a conserved NAD-ribose binding domain and an iron-sulfur domain.

The conversion of vanillate to protocatechuic acid is an intermediate step in the breakdown of lignin . While white rot fungi depolymerize lignin, bacterial microorganisms can further convert the aromatic degradation products that have arisen. In the case of protocatechuic acid, ring cleavage takes place and further metabolism. The formaldehyde released in the reaction catalyzed by VAN is converted by a glutathione- dependent formaldehyde dehydrogenase ( EC  1.2.1.1 ) because it is very toxic.

Individual evidence

  1. ↑ a b Makoto Hibi, Tomonori Sonoki, Hideo Mori: Functional coupling between vanillate-O-demethylase and formaldehyde detoxification pathway , in: FEMS Microbiol. Lett. , 2005 , 253  (2); Pp. 237-242; doi : 10.1016 / j.femsle.2005.09.036 ; PMID 1624286 .
  2. ↑ a b M. Nishimura, D. Ishiyama, J. Davies: Molecular cloning of streptomyces genes encoding vanillate demethylase. In: Bioscience, Biotechnology, and Biochemistry . Volume 70, Number 9, September 2006, pp. 2316-2319. PMID 16960359 .
  3. ↑ Miguel A. Providenti, Jason M. O'Brien, Jürgen Ruff, Alasdair M. Cook, Iain B. Lambert: Metabolism of isovanillate, vanillate, and veratrate by Comamonas testosteroni strain BR6020 , in: J. Bacteriol. , 2006 , 188  (11); Pp. 3862-3869; PMID 16707678 ; PMC 1482911 (free full text, PDF).