Archives of Microbiology

, Volume 168, Issue 4, pp 310–320

Anaerobic metabolism of l-phenylalanine via benzoyl-CoA in the denitrifying bacterium Thauera aromatica

  • Sabine Schneider
  • M. E.-S. Mohamed
  • G. Fuchs
Original paper

DOI: 10.1007/s002030050504

Cite this article as:
Schneider, S., Mohamed, MS. & Fuchs, G. Arch Microbiol (1997) 168: 310. doi:10.1007/s002030050504

Abstract

The anaerobic metabolism of phenylalanine was studied in the denitrifying bacterium Thauera aromatica, a member of the β-subclass of the Proteobacteria. Phenylalanine was completely oxidized and served as the sole source of cell carbon. Evidence is presented that degradation proceeds via benzoyl-CoA as the central aromatic intermediate; the aromatic ring-reducing enzyme benzoyl-CoA reductase was present in cells grown on phenylalanine. Intermediates in phenylalanine oxidation to benzoyl-CoA were phenylpyruvate, phenylacetaldehyde, phenylacetate, phenylacetyl-CoA, and phenylglyoxylate. The required enzymes were detected in extracts of cells grown with phenylalanine and nitrate. Oxidation of phenylalanine to benzoyl-CoA was catalyzed by phenylalanine transaminase, phenylpyruvate decarboxylase, phenylacetaldehyde dehydrogenase (NAD+), phenylacetate-CoA ligase (AMP-forming), enzyme(s) oxidizing phenylacetyl-CoA to phenylglyoxylate with nitrate, and phenylglyoxylate:acceptor oxidoreductase. The capacity for phenylalanine oxidation to phenylacetate was induced during growth with phenylalanine. Evidence is provided that α-oxidation of phenylacetyl-CoA is catalyzed by a membrane-bound enzyme. This is the first report on the complete anaerobic degradation of an aromatic amino acid and the regulation of this process.

Key wordsThauera aromatica l-phenylalanine metabolism Phenylalanine transaminase Phenylpyruvate decarboxylase Phenylacetaldehyde dehydrogenase Phenylacetate-CoA ligase α-Oxidation of phenylacetyl-CoA Phenylglyoxylate:acceptor oxidoreductase 

Copyright information

© Springer-Verlag Berlin Heidelberg 1997

Authors and Affiliations

  • Sabine Schneider
    • 1
  • M. E.-S. Mohamed
    • 1
  • G. Fuchs
    • 1
  1. 1.Mikrobiologie, Institut Biologie II, Universität Freiburg, Schänzlestr. 1, D-79104 Freiburg, Germany Tel. +49-761-203-2649; Fax +49-761-203–2626 e-mail: fuchsgeo@ruf.uni-freiburg.deDE

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