Regulation of Escherichia coli fumarate reductase (frdABCD) operon expression by respiratory electron acceptors and the fnr gene product

Jones, Helen; Gunsalus, Robert P.

doi:10.1128/jb.169.7.3340-3349.1987

Cited by 168 publications

(156 citation statements)

References 52 publications

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“…4). This effect has been documented previously in batch culture (7,16) and suggests that the cell has a second means to regulate gene expression in response to anaerobiosis.…”

Section: Resultsmentioning

confidence: 80%

Effect of cell growth rate on expression of the anaerobic respiratory pathway operons frdABCD, dmsABC, and narGHJI of Escherichia coli

et al. 1994

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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 offrdA-lacZ, dmnsA-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. WhereasfrdA-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 frr 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. Escherichia coli can respire either aerobically or anaerobically by using one of the alternative electron acceptors: oxygen, nitrate, trimethylamine-N-oxide (TMAO), dimethyl sulfoxide (DMSO), and fumarate. Depending on the availability of these respiratory substrates, the cell synthesizes one or more of the terminal enzymes of the electron transport pathways. DMSO-TMAO reductase, encoded by dmsABC, exhibits a broad substrate specificity for reducing TMAO, DMSO, and other amine-N-oxides (4, 28). Fumarate reductase readily catalyzes the interconversion of fumarate and succinate, although under physiological conditions, it is thought to perform the reductive reaction primarily during anaerobic growth (1). The four enzyme subunits are encoded by the frdABCD genes. The inducible nitrate reductase enzyme complex of E. coli which converts nitrate to nitrite during anaerobic cell growth is encoded by the narGHJI genes (13,27). The frdABCD, dmsABC, and narGHJI operons that encode the subunits of each enzyme complex are unlinked to one another and map at 94, 20, and 27 min on the E. coli chromosome, respectively (2).Expression of the anaerobic electron transport pathway operons is regulated in response to anaerobiosis and by the availability of nitrate (17, 18). The anaerobic response is mediated by the fnr gene product...

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“…4). This effect has been documented previously in batch culture (7,16) and suggests that the cell has a second means to regulate gene expression in response to anaerobiosis.…”

Section: Resultsmentioning

confidence: 80%

Effect of cell growth rate on expression of the anaerobic respiratory pathway operons frdABCD, dmsABC, and narGHJI of Escherichia coli

et al. 1994

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“…The junction of each fusion was confirmed by double-stranded DNA sequence analysis (33). The gene and operon fusions were then transferred onto the specialized lambda vector, XRZ5, and introduced into the chromosome of MC4100 as previously described (19). Lysogens that contained a single phage were isolated and stocked for subsequent study.…”

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confidence: 99%

Regulation of narK gene expression in Escherichia coli in response to anaerobiosis, nitrate, iron, and molybdenum

1992

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The regulation of the narK gene in Escherichia coli was studied by constructing narK-lacZ gene and operon fusions and analyzing their expression in various mutant strains in response to changes in cell growth conditions. Expression of narK-lacZ was induced 110-fold by a shift to anaerobic growth and a further 8-fold by the presence of nitrate. The fnr gene product mediates this anaerobic response, while nitrate control is mediated by the narL, narX, and narQ gene products. The narX and narQ gene products were shown to sense nitrate independently of one another and could each activate narK expression in a NarL-dependent manner. We provide the first evidence that NarL and FNR interact to ensure optimal expression of narK. IHF and Fis proteins are also required for full activation of narK expression, and their roles in DNA bending are discussed.Finally, the availability of molybdate and iron ions is necessary for optimal narK expression, whereas the availability of nitrite is not. Although the role of the narK gene product in cell metabolism remains uncertain, the pattern of narK gene expression is consistent with a proposed role of NarK in nitrate uptake by the cell for nitrate-linked electron transport.The narK gene in Escherichia coli, located at 27 min on the chromosome, is near the structural genes for nitrate reductase (narGHJI) plus two regulatory genes that are involved in nitrate-dependent gene expression, narX and narL (1,30,40). The narK gene was recently sequenced, and a role in nitrate transport was suggested on the basis of its similarity in protein sequence to a family of cytoplasmic membrane transport proteins (31). This role is supported by observations that nitrate uptake and metabolism are altered in narK mutants (9,17,31).In a previous study, narK expression was examined under anaerobic conditions and found to be impaired in strains defective in either narL or fnr (40). However, the effect of oxygen and nitrate on narK expression was not examined nor was the effect of varying other nutritional conditions. To address these questions, narK-lacZ fusions were constructed and inserted into the chromosome in single copy, and their expression was analyzed under a variety of conditions. The role of the narX, narQ, chlD, chlE, chU, fiur, fis, and himA gene products on narK-lacZ expression was documented as was the effect of limiting iron and molybdenum availability. The conditions optimal for narK expression are consistent with a role for NarK in nitrate transport and/or metabolism. MATERIALS AND METHODSBacterial strains, bacteriophages, and plasmids. The genotypes and origins of the E. coli K-12 strains, bacteriophage, and plasmids used are given in Table 1. Strains TK100 (hiNMA) and TK101 (fis) were constructed by P1 transduction of the respective mutations from SD1 and SD6 into MC4100/ XTS8 (7,35). By using the same approach, the TK102 (narQ), TK103 [A(narXL) narQ], and TK104 (fur) strains were constructed (Table 1).Construction of narK-acZ gene fusions. Phage M13IS4 was constructed by inserting a ...

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“…The fnr gene product positively controls the expression of the nar (8,20,29) and frd (15,18,20) operons. Though fnr mutation does not affect the expression of the structural gene torA, it results in a decrease in TMAO reductase activity (24,28).…”

Section: Discussionmentioning

confidence: 99%

A novel gene, torB, for trimethylamine N-oxide reductase in Escherichia coli.

Yamamoto¹,

Hohmura

Ishimoto

1989

J. Gen. Appl. Microbiol.

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Trimethylamine N-oxide (TMAO) reductase which is involved in anaerobic respiration is one of the molybdenum-containing enzymes in Escherichia coli. A mutant defective in the activity of TMAO reductase was isolated by inserting phage Mudl. The mutation was localized at 0.7 min adjacent to chlG on the E. coli chromosome, and was designated torB. The torB mutant grown anaerobically with TMAO contained 10-30% of the enzyme activity in the parent strain grown under the same condition and about 80% of the enzyme protein immuno-reactive with an antiserum against the TMAO reductase. The content of molybdopterin, an organic moiety of molybdenum cofactor, in the immuno-precipitate from extracts of the torB mutant was rather low, about 60% of that in the immuno-precipitate from the parent strain. The mutant showed a normal level of another molybdenum enzyme nitrate reductase activity when anaerobically grown with nitrate. These findings suggest that the torB gene is involved in the formation of the active enzyme of TMAO reductase through the processing of molybdenum cofactor. There was a marked expression of torB under anaerobic conditions, and TMAO was not required for it.Some bacteria can use trimethylamine N-oxide (TMAO) as a terminal electron acceptor under anaerobic conditions (3). In Escherichia cold, the electron transport system of TMAO reduction is composed of some dehydrogenases, cytochromes, quinones, and TMAO reductase. This bacterium has three to four forms of TMAO reductase which are electrophoretically distinguishable (27). TMAO reductase I and III are inducible by TMAO and are composed of two identical peptides and a single one, respectively (28; Yamamoto and Hinakura, unpublished). TMAO reductase

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Regulation of Escherichia coli fumarate reductase (frdABCD) operon expression by respiratory electron acceptors and the fnr gene product

Cited by 168 publications

References 52 publications

Effect of cell growth rate on expression of the anaerobic respiratory pathway operons frdABCD, dmsABC, and narGHJI of Escherichia coli

Effect of cell growth rate on expression of the anaerobic respiratory pathway operons frdABCD, dmsABC, and narGHJI of Escherichia coli

Regulation of narK gene expression in Escherichia coli in response to anaerobiosis, nitrate, iron, and molybdenum

A novel gene, torB, for trimethylamine N-oxide reductase in Escherichia coli.

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