title: The proteolytic activity of the HtrA (DegP) protein from Escherichia coli at low temperatures.
abstract: The HtrA (DegP) protein from Escherichia coli is a periplasmic protease whose function is to protect cells from the deleterious effects of various stress conditions. At temperatures below 28 degrees C the proteolytic activity of HtrA was regarded as negligible and it was believed that the protein mainly plays the role of a chaperone. In the present work we provide evidence that HtrA can in fact act as a protease at low temperatures. Under folding stress, caused by disturbances in the disulfide bond formation, the lack of proteolytic activity of HtrA lowered the survival rates of mutant strains deprived of a functional DsbA/DsbB oxidoreductase system. HtrA degraded efficiently the unfolded, reduced alkaline phosphatase at 20 degrees C, both in vivo and in vitro. The cleavage was most efficient in the case of HtrA deprived of its internal S-S bond; therefore we expect that the reduction of HtrA may play a regulatory role in proteolysis.
authors.affiliation: University of Gdansk, Department of Biochemistry, Kładki 24, 80-822 Gdansk, Poland.
authors.forename: Joanna
authors.initials: J
authors.lastname: Skorko-Glonek
authors.affiliation: University of Gdansk, Department of Biochemistry, Kładki 24, 80-822 Gdansk, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Sobiecka-Szkatula
authors.affiliation: University of Gdansk, Department of Biochemistry, Kładki 24, 80-822 Gdansk, Poland.
authors.forename: Joanna
authors.initials: J
authors.lastname: Narkiewicz
authors.affiliation: University of Gdansk, Department of Biochemistry, Kładki 24, 80-822 Gdansk, Poland.
authors.forename: Barbara
authors.initials: B
authors.lastname: Lipinska
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism*; D003080:Cold Temperature; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics / Q000502:physiology*; D029968:Escherichia coli Proteins / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D018869:Heat-Shock Response; D009154:Mutation; D010084:Oxidation-Reduction; D033903:Periplasmic Proteins / Q000235:genetics / Q000378:metabolism*; D019704:Protein Disulfide-Isomerases / Q000235:genetics; D017510:Protein Folding; D012697:Serine Endopeptidases / Q000235:genetics / Q000378:metabolism*
chemical_list: D029968:Escherichia coli Proteins; D006360:Heat-Shock Proteins; D033903:Periplasmic Proteins; D000469:Alkaline Phosphatase; C061682:DegP protease; D012697:Serine Endopeptidases; D019704:Protein Disulfide-Isomerases; C526648:dsbA protein, E coli