Val
Reaction: Acts on substrates that are at least partially unfolded. The cleavage site P1 residue is normally between a pair of hydrophobic residues, such as ValVal
Other name(s): DegP; DegP protease; HtrA; high temperature requirement protease A; HrtA heat shock protein; protease Do; Do protease
Comments: This serine endopeptidase is essential for the clearance of denatured or aggregated proteins from the inner-membrane and periplasmic space in Escherichia coli. Natural substrates of the enzyme include colicin A lysis protein, pilin subunits and MalS from E. coli [3]. The enzyme has weak peptidase activity with casein and other non-native substrates [3]. The peptidase acts as a chaperone at low temperatures but switches to a peptidase (heat shock protein) at higher temperatures [1,6]. Molecular chaperones and peptidases control the folded state of proteins by recognizing hydrophobic stretches of polypeptide that become exposed by misfolding or unfolding. They then bind these hydrophobic substrates to prevent aggregation or assist in protein refolding. If attempts at refolding fail, then irreversibly damaged proteins are degraded by peptidases such as this enzyme [6]. Belongs in peptidase family S1C.
Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number: 161108-11-8
References:
1. Lipinska, B., Zylicz, M. and Georgopoulos, C. The HtrA (DegP) protein, essential for Escherichia coli survival at high temperatures, is an endopeptidase. J. Bacteriol. 172 (1990) 1791-1797. [PMID: 2180903]
2. Seol, J.H., Woo, S.K., Jung, E.M., Yoo, S.J., Lee, C.S., Kim, K.J., Tanaka, K., Ichihara, A., Ha, D.B. and Chung, C.H. Protease Do is essential for survival of Escherichia coli at high temperatures: its identity with the htrA gene product. Biochem. Biophys. Res. Commun. 176 (1991) 730-736. [PMID: 2025286]
3. Jones, C.H., Dexter, P., Evans, A.K., Liu, C., Hultgren, S.J. and Hruby, D.E. Escherichia coli DegP protease cleaves between paired hydrophobic residues in a natural substrate: the PapA pilin. J. Bacteriol. 184 (2002) 5762-5771. [PMID: 12270835]
4. Swamy, K.H., Chung, C.H. and Goldberg, A.L. Isolation and characterization of protease Do from Escherichia coli, a large serine protease containing multiple subunits. Arch. Biochem. Biophys. 224 (1983) 543-554. [PMID: 6347072]
5. Pallen, M.J. and Wren, B.W. The HtrA family of serine proteases. Mol. Microbiol. 26 (1997) 209-221. [PMID: 9383148]
6. Krojer, T., Garrido-Franco, M., Huber, R., Ehrmann, M. and Clausen, T. Crystal structure of DegP (HtrA) reveals a new protease-chaperone machine. Nature 416 (2002) 455-459. [PMID: 11919638]