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Citrate utilization under anaerobic environment in Escherichia coli is under direct control of Fnr and indirect control of ArcA and Fnr via CitA‐CitB system
Author(s) -
Jiang Fengwei,
Huang Xinxin,
Barbieri Nicolle L.,
Logue Catherine M.,
Nolan Lisa K.,
Li Ganwu
Publication year - 2021
Publication title -
environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.954
H-Index - 188
eISSN - 1462-2920
pISSN - 1462-2912
DOI - 10.1111/1462-2920.15357
Subject(s) - escherichia coli , biology , fermentation , operon , microbiology and biotechnology , anaerobic exercise , bacteria , biochemistry , gene , genetics , physiology
Summary Most Escherichia coli ( E . coli ) strains do not cause disease, naturally living in the lower intestine and is expelled into the environment within faecal matter. Escherichia coli can utilize citrate under anaerobic conditions but not aerobic conditions. However, the underlying regulatory mechanisms are poorly understood. In this study, we explored regulatory mechanisms of citrate fermentation genes by global regulators ArcA and Fnr under anaerobic conditions. A gel mobility shift assay showed that the regulator proteins ArcA and Fnr binded to the promoter region localized between the citAB and citCDEFXGT operons. Subsequent assays confirmed that ArcA indirectly controled the expression of citrate fermentation genes via regulating CitA‐CitB system, while Fnr directly regulated but also indirectly modulated citrate fermentation genes via controling CitA‐CitB system. Deletions of arcA and fnr significantly reduced the growth of Escherichia coli in M9 medium with a citrate carbon source. We conclude that both ArcA and Fnr can indirectly control the citrate utilization via CitA‐CitB system, while Fnr can also directly regulate the expression of citrate fermentation genes in E . coli under anaerobic conditions.