title: Identification and characterization of 2-naphthoyl-coenzyme A reductase, the prototype of a novel class of dearomatizing reductases.
abstract: The enzymatic dearomatization of aromatic ring systems by reduction represents a highly challenging redox reaction in biology and plays a key role in the degradation of aromatic compounds under anoxic conditions. In anaerobic bacteria, most monocyclic aromatic growth substrates are converted to benzoyl-coenzyme A (CoA), which is then dearomatized to a conjugated dienoyl-CoA by ATP-dependent or -independent benzoyl-CoA reductases. It was unresolved whether or not related enzymes are involved in the anaerobic degradation of environmentally relevant polycyclic aromatic hydrocarbons (PAHs). In this work, a previously unknown dearomatizing 2-naphthoyl-CoA reductase was purified from extracts of the naphthalene-degrading, sulphidogenic enrichment culture N47. The oxygen-tolerant enzyme dearomatized the non-activated ring of 2-naphthoyl-CoA by a four-electron reduction to 5,6,7,8-tetrahydro-2-naphthoyl-CoA. The dimeric 150 kDa enzyme complex was composed of a 72 kDa subunit showing sequence similarity to members of the flavin-containing 'old yellow enzyme' family. NCR contained FAD, FMN, and an iron-sulphur cluster as cofactors. Extracts of Escherichia coli expressing the encoding gene catalysed 2-naphthoyl-CoA reduction. The identified NCR is a prototypical enzyme of a previously unknown class of dearomatizing arylcarboxyl-CoA reductases that are involved in anaerobic PAH degradation; it fundamentally differs from known benzoyl-CoA reductases.
authors: Institute for Biology II, University of Freiburg, Schänzlestr. 1, D-79104, Freiburg, Germany.
authors: Christian
authors: C
authors: Eberlein
authors: Sebastian
authors: S
authors: Estelmann
authors: Jana
authors: J
authors: Seifert
authors: Martin
authors: M
authors: von Bergen
authors: Michael
authors: M
authors: Müller
authors: Rainer U
authors: RU
authors: Meckenstock
authors: Matthias
authors: M
authors: Boll
mesh_terms: D000693:Anaerobiosis; D001711:Biotransformation; D002264:Carboxylic Acids / Q000378:metabolism*; D003065:Coenzyme A / Q000378:metabolism*; D003067:Coenzymes / Q000378:metabolism; D004783:Environmental Microbiology; D004926:Escherichia coli / Q000235:genetics; D005486:Flavin Mononucleotide / Q000378:metabolism; D005182:Flavin-Adenine Dinucleotide / Q000378:metabolism; D007506:Iron-Sulfur Proteins; D008970:Molecular Weight; D009281:Naphthalenes / Q000378:metabolism*; D010088:Oxidoreductases / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D055503:Protein Multimerization; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D002264:Carboxylic Acids; D003067:Coenzymes; D007506:Iron-Sulfur Proteins; D009281:Naphthalenes; D011994:Recombinant Proteins; D005182:Flavin-Adenine Dinucleotide; C031721:naphthalene; C085312:1-naphthoic acid; D005486:Flavin Mononucleotide; D010088:Oxidoreductases; D003065:Coenzyme A