ISSN:
1432-072X
Keywords:
Key wordsThauera aromatica
;
l-phenylalanine
;
metabolism
;
Phenylalanine transaminase
;
Phenylpyruvate decarboxylase
;
Phenylacetaldehyde
;
dehydrogenase
;
Phenylacetate-CoA ligase
;
α-Oxidation
;
of phenylacetyl-CoA
;
Phenylglyoxylate:acceptor
;
oxidoreductase
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
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.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s002030050504
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