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The genetic basis of tetrathionate respiration in Salmonella typhimurium
The ttrRSBCA gene cluster confers on Escherichia coli the ability to respire with tetrathionate as electron acceptor and makes up a previously unrecognized class of molybdopterin‐dependent enzymes that carry out the reductive cleavage of sulphur–sulphur bonds.
Mechanism of regulation of the formate‐hydrogenlyase pathway by oxygen, nitrate, and pH: definition of the formate regulon
Observations indicate that it is the intracellular level of formate that determines the transcription of the genes of the formate regulon by FhlA, a novel positive feedback mechanism in which the activator of a regulon induces its own synthesis in response to increases in the concentration of the catabolic substrate.
The hydrogenases and formate dehydrogenases ofEscherichia coli
- G. Sawers
- BiologyAntonie van Leeuwenhoek
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, and 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 dehydrationases and hydrogenases.
Isolation and characterization of hypophosphite‐resistant mutants of Escherichia coli: identification of the FocA protein, encoded by the pfl operon, as a putative formate transporter
Results indicate that formate accumulates in anaerobic ceils which do not have a functional focA gene product and that one function of FocA may be to export formate from the cell, and suggest that FOCA may also be functional in the import of formate into an aerobic Escherichia coli cells.
Selenocysteine: the 21st amino acid
The aim of this article is to review the events leading to the elucidation of selenocysteine as being the 21st amino acid.
Transcriptional regulation in response to oxygen and nitrate of the operons encoding the [NiFe] hydrogenases 1 and 2 of Escherichia coli.
Data indicate that although the hya and hyb operons share common regulators, there are important differences in the control of expression of the individual operons.
The ArcBA Two-Component System of Escherichia coli Is Regulated by the Redox State of both the Ubiquinone and the Menaquinone Pool
- M. Bekker, S. Alexeeva, W. Laan, G. Sawers, Joost Teixeira de Mattos, K. Hellingwerf
- BiologyJournal of bacteriology
- 20 November 2009
The results lead to the working hypothesis that the in vivo activity of ArcB in E. coli is modulated by the redox state of the menaquinone pool and that the ubiquinone/ubiquinol ratio in vivo surely is not the only determinant for ArcB activity.
Novel transcriptional control of the pyruvate formate-lyase gene: upstream regulatory sequences and multiple promoters regulate anaerobic expression
Analysis of RNA transcripts by Northern blot hybridization demonstrated that the genes for orf and pfl were cotranscribed as an operon but that the pfl gene was also transcribed alone.
Novel keto acid formate‐lyase and propionate kinase enzymes are components of an anaerobic pathway in Escherichia coli that degrades L‐threonine to propionate
It is confirmed that 2‐ketobutyrate, the product of threonine deamination, is converted in vivo by TdcE to propionyl‐CoA, and revealed that Pfl and an as yet unidentified thiamine pyrophosphate‐dependent enzyme(s) can perform this reaction.
RirA, an iron-responsive regulator in the symbiotic bacterium Rhizobium leguminosarum.
Mutations in a Rhizobium leguminosarum gene, rirA (rhizobial iron regulator), caused high-level, constitutive expression of at least eight operons whose transcription is normally Fe-responsive and…