Formate-nitrate respiration in Salmonella typhimurium: studies of two rha-linked fdn genes

Paveglio, M T; Tang, Jane; Unger, Ronald E.; Barrett, Ericka L.

doi:10.1128/jb.170.1.213-217.1988

Cited by 12 publications

(14 citation statements)

References 27 publications

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“…Indeed, we originally identified our fdhD+ plasmids on the basis of their complementation patterns in the S. typhimurium mutants; subsequent comparison of our plasmids with those of Schlindwein et al (28) (Table 3). Finally, it has been suggested that fdnB encoded a structural component of cyt bFd, (26). However, our analysis of the fdnGHI operon of E. coli has shown that the structural gene for this cytochrome is encoded byfdnI (4,5 Table 2).…”

Section: Mo)mentioning

confidence: 67%

“…As VJS691 but X(4fdnG-laCZ)UGA (2,3,20,26). We used MacConkey-nitrate medium to screen TnJO-mutagenized colonies of E. coli.…”

Section: Mo)mentioning

confidence: 99%

“…Two additional genes affecting FDH-N activity have been identified in E. coli (fdhD and fdhE) and S. typhimurium (fdnB and fdnC) (2,3,23,26,28). In both organisms, these genes map at 88 min, between rha and glnA (23,26).…”

mentioning

confidence: 99%

“…In both organisms, these genes map at 88 min, between rha and glnA (23,26). Strains with fdhE and fdnB lesions lack FDH-N activity but retain essentially wild-type levels of FDH-H activity and gas production.…”

mentioning

confidence: 99%

“…Thus, fdhE+ (fdnB+) may be specifically involved in the synthesis or activity of FDH-N. Strains with fdhD and fdnC lesions are also devoid of FDH-N activity, but they also exhibit defects in FDH-H activity and gas production, which are more or less severe depending on growth and assay conditions (23,26). Bulk cytochrome b is poorly reduced by formate in both types of mutants, suggesting that they may have defects in electron transfer to or synthesis of cyt bFd6n (3,23).…”

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confidence: 99%

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Genetic evidence that genes fdhD and fdhE do not control synthesis of formate dehydrogenase-N in Escherichia coli K-12

1991

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Enterobacteria synthesize two formate dehydrogenases, formate dehydrogenase-N (encoded byfdnGHI) and formate dehydrogenase H (encoded by fdhF). Previous work has identified two rha-linked Salmonella typhimurium genes, fdnB and fdnC, which are required primarily for formate dehydrogenase-N activity. Analogous mutants, termed fdhD and fdhE, have been isolated in Escherichia coli. We used gene fusions betweenfdnG, the structural gene for the large subunit of formate dehydrogenase-N, and lacZ, the structural gene for I-galactosidase, to examine E. coli fdnGHI operon expression in fdhD and fdhE insertion mutants. Expression of the 4'(fdnG-lacZ) gene fusions was little affected by these insertions, suggesting that fdhD and fdhE do not control transcription or UGA decoding of the formate dehydrogenase-N structural genes. Our complementation tests, with cloned E. coli fdhD and fdhE genes, indicate that the S. typhimurium fdnC and fdnB genes are functionally homologous to the E. coli fdhD and fdhE genes, respectively.Formate (HCO2-) is a product of anaerobic pyruvate cleavage. Enterobacteria have two pathways for anaerobic metabolism of formate (Fig. 1). A respiratory pathway, formate-nitrate oxidoreductase, allows for energy conservation via oxidative phosphorylation during anaerobic growth. This pathway involves two membrane-bound, multisubunit enzymes, formate dehydrogenase-N (FDH-N) and respiratory nitrate reductase. Synthesis of this enzyme complex is induced by nitrate during anaerobic growth. FDH-N and respiratory nitrate reductase are associated with specific cytochromes, cyt bId' and cyt bNa,j, respectively. The strongly electronegative redox potential of the C02-HCO2-couple (Eo' = -432 mV) makes formate an efficient electron donor for respiratory nitrate reduction. The second pathway, formate-hydrogen lyase, operates anaerobically in the absence of nitrate. This pathway involves two enzymes, formate dehydrogenase-H (FDH-H) and hydrogenase 3. Synthesis of this enzyme complex is induced by anaerobiosis only in the absence of nitrate. The exact physiological role of formate-hydrogen lyase is not established. The H2 and CO2 produced by formate-hydrogen lyase accumulates in Durham tubes, so gas production provides a qualitative estimate of this activity. Formate metabolism in enterobacteria has been recently reviewed (33).The three subunits of FDH-N are encoded by the fdnGHI operon at 32 min on the Escherichia coli genetic map (5). The FDH-H polypeptide is encoded by the fdhF gene at 92 min on the E. coli map (27). The FdnG and FdhF polypeptides each contain selenium in the form of selenocysteine, and each associates with molybdenum cofactor. Thus, mutants defective in selenocysteine (sel) or molybdenum cofactor (chl) synthesis or incorporation are devoid of formate dehydrogenase activity (for reviews, see references 7 and 33).Analysis of E. coli and Salmonella typhimurium has identified four sel genes (originally termed fdh), lesions in which abolish the activities of 20,24). The selA (80 min) and selD (38 min) gen...

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Section: Mo)mentioning

confidence: 67%

“…As VJS691 but X(4fdnG-laCZ)UGA (2,3,20,26). We used MacConkey-nitrate medium to screen TnJO-mutagenized colonies of E. coli.…”

Section: Mo)mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Genetic evidence that genes fdhD and fdhE do not control synthesis of formate dehydrogenase-N in Escherichia coli K-12

1991

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The hydrogenases and formate dehydrogenases ofEscherichia coli

Sawers¹

1994

Antonie van Leeuwenhoek

223

205

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Escherichia coli has the capacity to synthesise three distinct formate dehydrogenase isoenzymes and three hydrogenase isoenzymes. All six are multisubunit, membrane-associated proteins that are functional in the anaerobic metabolism of the organism. One of the formate dehydrogenase isoenzymes is also synthesised in aerobic cells. Two of the formate dehydrogenase enzymes and two hydrogenases have a respiratory function while the formate dehydrogenase and hydrogenase associated with the formate hydrogenlyase pathway are not involved in energy conservation. The three formate dehydrogenases are molybdo-selenoproteins while the three hydrogenases are nickel enzymes; all six enzymes have an abundance of iron-sulfur clusters. These metal requirements alone invoke the necessity for a profusion of ancillary enzymes which are involved in the preparation and incorporation of these cofactors. The characterisation of a large number of pleiotropic mutants unable to synthesise either functionally active formate dehydrogenases or hydrogenases has led to the identification of a number of these enzymes. However, it is apparent that there are many more accessory proteins involved in the biosynthesis of these isoenzymes than originally anticipated. The biochemical function of the vast majority of these enzymes is not understood. Nevertheless, through the construction and study of defined mutants, together with sequence comparisons with homologous proteins from other organisms, it has been possible at least to categorise them with regard to a general requirement for the biosynthesis of all three isoenzymes or whether they have a specific function in the assembly of a particular enzyme. The identification of the structural genes encoding the formate dehydrogenase and hydrogenase isoenzymes has enabled a detailed dissection of how their expression is coordinated to the metabolic requirement for their products. Slowly, a picture is emerging of the extremely complex and involved path of events leading to the regulated synthesis, processing and assembly of catalytically active formate dehydrogenase and hydrogenase isoenzymes. This article aims to review the current state of knowledge regarding the biochemistry, genetics, molecular biology and physiology of these enzymes.

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Structural genes for nitrate-inducible formate dehydrogenase in Escherichia coli K-12.

Berg¹,

Stewart²

1990

Genetics

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Formate oxidation coupled to nitrate reduction constitutes a major anaerobic respiratory pathway in Escherichia coli. This respiratory chain consists of formate dehydrogenase-N, quinone, and nitrate reductase. We have isolated a recombinant DNA clone that likely contains the structural genes, fdnGHI, for the three subunits of formate dehydrogenase-N. The fdnGHI clone produced proteins of 110, 32 and 20 kDa which correspond to the subunit sizes of purified formate dehydrogenase-N. Our analysis indicates that fdnGHI is organized as an operon. We mapped the fdn operon to 32 min on the E. coli genetic map, close to the genes for cryptic nitrate reductase (encoded by the narZ operon). Expression of phi(fdnG-lacZ) operon fusions was induced by anaerobiosis and nitrate. This induction required fnr+ and narL+, two regulatory genes whose products are also required for the anaerobic, nitrate-inducible activation of the nitrate reductase structural gene operon, narGHJI. We conclude that regulation of fdnGHI and narGHJI expression is mediated through common pathways.

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Formate-nitrate respiration in Salmonella typhimurium: studies of two rha-linked fdn genes

Cited by 12 publications

References 27 publications

Genetic evidence that genes fdhD and fdhE do not control synthesis of formate dehydrogenase-N in Escherichia coli K-12

Genetic evidence that genes fdhD and fdhE do not control synthesis of formate dehydrogenase-N in Escherichia coli K-12

The hydrogenases and formate dehydrogenases ofEscherichia coli

Structural genes for nitrate-inducible formate dehydrogenase in Escherichia coli K-12.

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