Journal of Bacteriology, December 2001, p. 6936-6942, Vol. 183, No. 23
0021-9193/01/$04.00+0 DOI: 10.1128/JB.183.23.6936-6942.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
Institut für Mikrobiologie, Universität Stuttgart, 70569 Stuttgart,1 and Fachgebiet Wasserreinhaltung, Technische Universität Berlin, Sekr. KF4, 10623 Berlin,2 Germany
Received 8 June 2001/Accepted 10 September 2001
In cell extracts of Pseudaminobacter salicylatoxidans strain BN12, an enzymatic activity was detected which converted salicylate in an oxygen-dependent but NAD(P)H-independent reaction to a product with an absorbance maximum at 283 nm. This metabolite was isolated, purified, and identified by mass spectrometry and 1H and 13C nuclear magnetic resonance spectroscopy as 2-oxohepta-3,5-dienedioic acid. This metabolite could be formed only by direct ring fission of salicylate by a 1,2-dioxygenase reaction. Cell extracts from P. salicylatoxidans also oxidized 5-aminosalicylate, 3-, 4-, and 5-chlorosalicylate, 3-, 4-, and 5-methylsalicylate, 3- and 5-hydroxysalicylate (gentisate), and 1-hydroxy-2-naphthoate. The dioxygenase was purified and shown to consist of four identical subunits with a molecular weight of about 45,000. The purified enzyme showed higher catalytic constants with gentisate or 1-hydroxy-2-naphthoate than with salicylate. It was therefore concluded that P. salicylatoxidans synthesized a gentisate 1,2-dioxygenase with an extraordinary substrate range, which also allowed the oxidation of salicylate.
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