title: Expression of Escherichia coli glutaredoxin 2 is mainly regulated by ppGpp and sigmaS.
abstract: Escherichia coli glutaredoxin 2 (Grx2, encoded by grxB) differs greatly from the other two glutaredoxins in structure and catalytic properties. In a wild type strain, levels of Grx2 increased 3-fold in the stationary phase (up to 8 microg/mg). Guanosine-3',5'-tetraphoshate (ppGpp) and sigma(S), which regulate the transcription of genes in the stationary phase, dramatically affected the expression of Grx2. spoTrelA null mutants, lacking ppGpp, had very low levels of Grx2, while overproduction of full-length RelA or valine-induced starvation of isoleucine, both conditions elevating ppGpp levels, resulted in elevation of Grx2. Null mutants for the sigma(S)-specific protease ClpP, which have higher levels of sigma(S), exhibited a 3-fold Grx2 increase. sigma(S) in trans also increased the levels of Grx2. Therefore the stationary phase expression of Grx2 is determined by the sigma(S)-bound form of RNA polymerase in connection with ppGpp, while basal levels should be attributed to sigma(70)-RNA polymerase holoenzyme. Osmotic pressure and cAMP also affected the expression of Grx2, presumably via sigma(S). Furthermore, Grx2 levels were elevated in an oxyR(-) strain. In accordance with the role of Grx2 as a stationary phase protein, null mutants for grxB were shown to lyse under starvation conditions and exhibited a distorted morphology.
authors.affiliation: Medical Nobel Institute for Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, S-171 77 Stockholm, Sweden.
authors.forename: Aristi
authors.initials: A
authors.lastname: Potamitou
authors.forename: Peter
authors.initials: P
authors.lastname: Neubauer
authors.forename: Arne
authors.initials: A
authors.lastname: Holmgren
authors.forename: Alexios
authors.initials: A
authors.lastname: Vlamis-Gardikas
mesh_terms: D001426:Bacterial Proteins / Q000502:physiology*; D004797:Enzyme-Linked Immunosorbent Assay; D004926:Escherichia coli / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism; D054477:Glutaredoxins; D006159:Guanosine Tetraphosphate / Q000502:physiology*; D006861:Hydrogen Peroxide / Q000378:metabolism; D007532:Isoleucine / Q000494:pharmacology; D007544:Isopropyl Thiogalactoside / Q000494:pharmacology; D016328:NF-kappa B / Q000096:biosynthesis; D009997:Osmotic Pressure; D010088:Oxidoreductases; D014176:Protein Biosynthesis; D012808:Sigma Factor / Q000502:physiology*; D051996:Transcription Factor RelA; D014633:Valine / Q000494:pharmacology
chemical_list: D001426:Bacterial Proteins; D054477:Glutaredoxins; D016328:NF-kappa B; D012808:Sigma Factor; D051996:Transcription Factor RelA; C069567:sigma factor KatF protein, Bacteria; D007532:Isoleucine; D006159:Guanosine Tetraphosphate; D007544:Isopropyl Thiogalactoside; D006861:Hydrogen Peroxide; D010088:Oxidoreductases; D014633:Valine; D005947:Glucose