Identification and characterization of 2-naphthoyl-coenzyme A reductase, the prototype of a novel class of dearomatizing reductases

Christian Eberlein, Sebastian Estelmann, Jana Seifert, Martin Von Bergen, Michael Müller, Rainer U. Meckenstock, Matthias Boll

Research output: Contribution to journalArticlepeer-review

41 Scopus citations

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 150kDa enzyme complex was composed of a 72kDa 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.

Original languageEnglish
Pages (from-to)1032-1039
Number of pages8
JournalMolecular Microbiology
Volume88
Issue number5
DOIs
StatePublished - Jun 2013
Externally publishedYes

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