Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P51532 (transcriptional activator)
 6,546 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

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 mumol 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 mumol/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 O2 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 Fe2+ under physiological conditions. Therefore FNR does not communicate with the iron pool regulating the Fur protein.
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PMID:Iron content and FNR-dependent gene regulation in Escherichia coli. 180 64

The fumarate reductase (frdABCD), dimethyl sulfoxide (DMSO)-trimethylamine-N-oxide (TMAO) reductase (dmsABC), and nitrate reductase (narGHJI) operons in Escherichia coli encode enzymes involved in anaerobic respiration to the electron acceptors fumarate, DMSO or TMAO, and nitrate, respectively. They are regulated in response to anaerobiosis and nitrate availability. To determine how each operon is regulated in response to changes in cell growth rate and in oxygen availability, expression of frdA-lacZ, dmsA-lacZ, and narG-lacZ fusion genes was examined during continuous culture. After a change in the cell growth rate, each anaerobic electron transport pathway operon fusion responded somewhat differently. Whereas frdA-lacZ expression increased by fivefold as the growth rate decreased from 0.60 to 0.12/hour during aerobic growth, little change was seen under anaerobic conditions. In contrast, growth rate-dependent expression of narG-lacZ expression occurred under anaerobic conditions but not under aerobic conditions. Finally, dmsA-lacZ expression did not vary greatly for any of the growth rates tested. When cells were shifted from aerobic to anaerobic growth conditions, expression of each fusion increased at a moderate rate and peaked or "overshot" before reaching a new equilibrium value. This "overshoot" phenomenon was independent of the fnr gene product, which functions as a transcriptional activator of each respiratory operon during anaerobic conditions. In contrast to the moderate rate of anaerobic induction seen for narG-lacZ expression, the addition of nitrate caused a rapid induction response. The cell appears to have many ways to adjust cell respiration in response to changes in cell growth conditions.
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PMID:Effect of cell growth rate on expression of the anaerobic respiratory pathway operons frdABCD, dmsABC, and narGHJI of Escherichia coli. 796 11