Open AccessIron content and FNR‐dependent gene regulation in Escherichia coli
Author(s) -
Niehaus F.,
Hantke K.,
Unden G.
Publication year - 1991
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1991.tb04617.x
Subject(s) - escherichia coli , anaerobic exercise , operon , gene expression , ferrous , lac operon , biology , bacteria , biochemistry , fumarate reductase , activator (genetics) , gene , reductase , chemistry , microbiology and biotechnology , enzyme , genetics , physiology , organic chemistry
The significance of intracellular iron levels of Escherichia coli on the expression of the fumarate reductase operon ( frd ), which is regulated by the transcriptional activator FNR, was studied in vivo. The iron contents of aerobically and anaerobically grown E. coli were determined and related to the expression of frd and of genes ( fiu, fepA, fhuF ) which are regulated by the iron uptake regulatory protein Fur. The iron contents varied from 1.6 to 6.9 μmol Fe/g protein with no significant difference in aerobic and anaerobic bacteria. Expression of frd was not related to the different iron levels, but to oxygen supply. Only severe iron limitation in iron‐depleted medium, which caused lower iron contents (0.8 to 1.6 μmol/g), reduced the expression of frd under anaerobic conditions. On the other hand, expression of fiu, fepA and fhuF clearly responded to iron supply and cellular content, but only slightly to changed O 2 supply. Generally, expression of frd responded only to much stricter iron limitation, than expression of Fur regulated genes. It is concluded that the functional state of FNR during aerobic/anaerobic switch is not regulated by iron content and reversible binding of Fe 2+ under physiological conditions. Therefore FNR does not communicate with the iron pool regulating the Fur protein.