Characterization of degP, a gene required for proteolysis in the cell envelope and essential for growth of Escherichia coli at high temperature

Abstract

The degP gene, required for proteolysis in the cell envelope of Escherichia coli, maps at approximately 3.5 min on the chromosome. Null mutations in degP result in temperature-sensitive growth. In certain genetic backgrounds, expression of abnormal periplasmic or inner membrane proteins (protein fusions or proteins with internal deletions) enhances the temperature-sensitive phenotype. Such growth defects were used as a selection for cloning the degP gene into Mud4042 and pACYC184 plasmid vectors, and a restriction map was determined. Analysis of deletion and insertion mutations on one of these plasmids showed that the degP gene is approximately 1.5 kilobases in size. The plasmid-encoded DegP protein had an apparent molecular weight of 50,000, as determined by maxicell analysis. Protein fusions between DegP and alkaline phosphatase had high alkaline phosphatase enzymatic activity, indicating that DegP is a periplasmic or membrane protein.

Identification of the Escherichia coli sohB gene, a multicopy suppressor of the HtrA (DegP) null phenotype

“…Other workers discovered the htrA gene independently using a different approach, and they named the gene degP (33). Their work involved the characterization of mutants defective in the proteolysis of certain periplasmic fusion proteins (34). Thus, the product of the htrA (degP) gene is a periplasmic protease that is required only at elevated temperature.…”

The C‐terminal domain of the secretin PulD contains the binding site for its cognate chaperone, PulS, and confers PulS dependence on pIVf1 function

“…Degradation of pIV-PulD 65 and/or PulD in the absence of PulS was not prevented in strains individually or simultaneously deleted for the genes encoding the outer membrane protease OmpT (Sugimura and Nishihara, 1988), or the periplasmic proteases DegP (Strauch et al, 1989), Tsp (Keiler and Sauer, 1996), Ptr (Finch et al, 1986), or HhoA and HhoB (Bass et al, 1996).…”

The HtrA family of serine proteases

“…On the one hand, HtrA is not released on osmotic shock, suggesting that it is cytosolic (Swamy and Goldberg, 1982); on the other hand, HtrA has a signal peptide and HtrA-alkaline phosphatase fusion proteins show alkaline phosphatase activity, suggesting a periplasmic or membrane location (Strauch et al, 1989). Skorko-Glonek et al (1997) HtrA's role in the cell htrA mutants and suppressors In E. coli, the htrA gene was identified by two phenotypes of htrA null mutants: thermosensitivity (Lipinska et al, 1988) and decreased degradation of abnormal periplasmic proteins (Strauch and Beckwith, 1988;Strauch et al, 1989). Null mutants also showed a slightly decreased growth rate in rich medium at 37ЊC and an increased lag phase (Seol et al, 1991).…”