Characterization of the anthranilate degradation pathway in Geobacillus thermodenitrificans NG80-2

Abstract

Anthranilate is an important intermediate of tryptophan metabolism. In this study, a hydroxylase system consisting of an FADH2-utilizing monooxygenase (GTNG_3160) and an FAD reductase (GTNG_3158), as well as a bifunctional riboflavin kinase/FMN adenylyltransferase (GTNG_3159), encoded in the anthranilate degradation gene cluster inGeobacillus thermodenitrificansNG80-2 were functionally characterizedin vitro. GTNG_3159 produces FAD to be reduced by GTNG_3158 and the reduced FAD (FADH2) is utilized by GTNG_3160 to convert anthranilate to 3-hydroxyanthranilate (3-HAA), which is further degraded to acetyl-CoA through ameta-cleavage pathway also encoded in the gene cluster. Utilization of this pathway for the degradation of anthranilate and tryptophan by NG80-2 under physiological conditions was confirmed by real-time RT-PCR analysis of representative genes. This is believed to be the first time that the degradation pathway of anthranilate via 3-HAA has been characterized in a bacterium. This pathway is likely to play an important role in the survival ofG. thermodenitrificansin the oil reservoir conditions from which strain NG80-2 was isolated.