Benzoate metabolism intermediate benzoyl coenzyme A affects gentisate pathway regulation in Comamonas testosteroni.
A previous study showed that benzoate was catabolized via a coenzyme A (CoA)-dependent epoxide pathway in Azoarcus evansii (R. Niemetz, U. Altenschmidt, S. Brucker, and G. Fuchs, Eur. J. Biochem. 227:161-168, 1995), but gentisate 1,2-dioxygenase was induced. Similarly, we found that the Comamonas testosteroni strain CNB-1 degraded benzoate via a CoA-dependent epoxide pathway and that gentisate 1,2-dioxygenase (GenA) was also induced when benzoate or 3-hydroxybenzoate served as a carbon source for growth. Genes encoding the CoA-dependent epoxide (box genes) and gentisate (gen genes) pathways were identified. Genetic disruption revealed that the gen genes were not involved in benzoate and 3-hydroxybenzoate degradation. Hence, we investigated gen gene regulation in the CNB-1 strain. The PgenA promoter, a MarR-type regulator (GenR), and the GenR binding site were identified. We found that GenR took gentisate, 3-hydroxybenzoate, and benzoyl-CoA as effectors and that binding of GenR to its target DNA sequence was prohibited when these effectors were present. In vivo studies showed that the CNB-1 mutant that lost benzoyl-CoA synthesis was not able to activate PgenA promoter, while transcription of genA was upregulated in another CNB-1 mutant that lost the ability to degrade benzoyl-CoA. The finding that benzoyl-CoA (a metabolic intermediate of benzoate degradation) and 3-hydroxybenzoate function as GenR effectors explains why GenA was induced when CNB-1 grew on benzoate or 3-hydroxybenzoate. Regulation of gentisate pathways by MarR-, LysR-, and IclR-type regulators in diverse bacterial groups is discussed in detail.
State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, People's Republic of China University of Chinese Academy of Sciences, Beijing, People's Republic of China.
Dong-Wei
DW
Chen
CAS Key Laboratory of Microbial Physiological and Metabolic Engineering at Institute of Microbiology, Chinese Academy of Sciences, Beijing, People's Republic of China.
Yun
Y
Zhang
State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, People's Republic of China Environmental Microbiology Research Center, Institute of Microbiology, Chinese Academy of Sciences, Beijing, People's Republic of China.
Cheng-Ying
CY
Jiang
State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, People's Republic of China Environmental Microbiology Research Center, Institute of Microbiology, Chinese Academy of Sciences, Beijing, People's Republic of China liusj@im.ac.cn.
Shuang-Jiang
SJ
Liu
D000214:Acyl Coenzyme A / Q000378:metabolism*; D001565:Benzoates / Q000378:metabolism*; D020604:Comamonas testosteroni / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D003470:Culture Media / Q000737:chemistry; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D005841:Gentisates / Q000378:metabolism*; D053858:Metabolic Networks and Pathways / Q000235:genetics
D000214:Acyl Coenzyme A; D001565:Benzoates; D003470:Culture Media; D005841:Gentisates; C037817:benzoyl-coenzyme A