(R)-Benzylsuccinyl-CoA dehydrogenase of Thauera aromatica, an enzyme of the anaerobic toluene catabolic pathway.
The first intermediate of anaerobic toluene catabolism, (R)-benzylsuccinate, is formed by enzymic addition of the methyl group of toluene to a fumarate cosubstrate and is subsequently activated to (R)-2-benzylsuccinyl-CoA. This compound is then oxidised to benzoyl-CoA and succinyl-CoA by a specific beta-oxidation pathway. The enzyme catalysing the first oxidation step of this pathway, (R)-benzylsuccinyl-CoA dehydrogenase, is encoded by the bbsG gene in Thauera aromatica. It was functionally overproduced in Escherichia coli, purified and characterised. The enzyme is a homotetramer with a subunit size of 45 kDa and contains one FAD per subunit. It is highly specific for (R)-benzylsuccinyl-CoA and is inhibited by (S)-benzylsuccinyl-CoA. An apparent K(m) value of 110+/-10 micro M was obtained for (R)-benzylsuccinyl-CoA. The reaction product of (R)-benzylsuccinyl-CoA dehydrogenase was identified as (E)-benzylidene-succinyl-CoA by comparison with the chemically synthesised compound, which was obtained via a new synthetic procedure. (R)-Benzylsuccinyl-CoA dehydrogenase was detected as a specifically substrate-induced protein in toluene- and m-xylene-grown cells of several bacterial species, using enzyme activity and immunological detection.
Leutwein
Christina
C
Mikrobiologie, Institut für Biologie II, Albert-Ludwigs-Universität, Schänzlestrasse 1, 79104 Freiburg, Germany.
Heider
Johann
J
D000693:Anaerobiosis; D001426:Bacterial Proteins; D002384:Catalysis; D004591:Electrophoresis, Polyacrylamide Gel; D010088:Oxidoreductases / Q000302:isolation & purification / Q000378:metabolism*; D020628:Thauera / Q000201:enzymology* / Q000378:metabolism; D014050:Toluene / Q000737:chemistry / Q000378:metabolism*
D001426:Bacterial Proteins; D014050:Toluene; D010088:Oxidoreductases; C403325:BbsG protein, Thauera aromatica