Comparative genome and transcriptome of Rhodococcus pyridinivorans GF3 for analyzing the detoxification mechanism of...

Anthraquinone compounds (ACs) could be efficiently degraded and detoxified by bacteria. However, the molecular mechanism of bacterial degradation and detoxification of ACs remains unclear. In this study, 1-aminoanthraquinone-2-sulfonate (ASA-2) was used as a model anthraquinone compound, the response mechanism of Rhodococcus pyridinivorans GF3 to ASA-2 using genomics and transcriptomics techniques was investigated. Comparative genome analysis showed that strain GF3 owned an especial gene region (Genes 1337-1399) containing the genes encoding cytochrome P450, monooxygenase, dehydrogenase and oxidoreductase, which did not commonly exist in Rhodococcus genus. The amino acid sequences of these genes were similar to those of the cleavage enzymes of anthraquinone ring in Aspergillus genus. Moreover, the transcriptions of Genes 1392-1394 (cytochrome 450 gene cluster) displayed 1.8-3.1-fold up-regulation under ASA-2 exposure. Meanwhile, as an intermediate product of ASA-2, catechol was degraded to acetyl-CoA, succinyl-CoA and pyruvate, resulting in the enhanced tricarboxylic acid cycle and ATP generation. This process also promoted the up-regulation of the genes encoding resistance, efflux, transporter and anti-oxidation pressure proteins, which were involved in resisting ASA-2 and maintaining the homeostasis of cells. These results provided us with a further understanding of the molecular mechanism of degradation and detoxification of ACs.