| Structural highlights
Function
[DEGP_ECOLI] DegP acts as a chaperone at low temperatures but switches to a peptidase (heat shock protein) at higher temperatures. It degrades transiently denatured and unfolded proteins which accumulate in the periplasm following heat shock or other stress conditions. DegP is efficient with Val-Xaa and Ile-Xaa peptide bonds, suggesting a preference for beta-branched side chain amino acids. Only unfolded proteins devoid of disulfide bonds appear capable of being cleaved, thereby preventing non-specific proteolysis of folded proteins. Its proteolytic activity is essential for the survival of cells at elevated temperatures. It can degrade IciA, ada, casein, globin and PapA. DegP shares specificity with DegQ. DegP is also involved in the biogenesis of partially folded outer-membrane proteins (OMP).[1] [2] [3] [4] [5] [6] [OMPC_ECOLI] Forms pores that allow passive diffusion of small molecules across the outer membrane.
Publication Abstract from PubMed
The HtrA protein family combines chaperone and protease activities and is essential for protein quality control in many organisms. Whereas the mechanisms underlying the proteolytic function of HtrA proteins are well characterized, their chaperone activity remains poorly understood. Here we describe cryo-EM structures of Escherichia coli DegQ in its 12- and 24-mer states in complex with model substrates, providing a structural model of HtrA chaperone action. Up to six lysozyme substrates bind inside the DegQ 12-mer cage and are visualized in a close-to-native state. An asymmetric reconstruction reveals the binding of a well-ordered lysozyme to four DegQ protomers. DegQ PDZ domains are located adjacent to substrate density and their presence is required for chaperone activity. The substrate-interacting regions appear conserved in 12- and 24-mer cages, suggesting a common mechanism of chaperone function.
Newly folded substrates inside the molecular cage of the HtrA chaperone DegQ.,Malet H, Canellas F, Sawa J, Yan J, Thalassinos K, Ehrmann M, Clausen T, Saibil HR Nat Struct Mol Biol. 2012 Jan 15;19(2):152-7. doi: 10.1038/nsmb.2210. PMID:22245966[7]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Lipinska B, Zylicz M, Georgopoulos C. The HtrA (DegP) protein, essential for Escherichia coli survival at high temperatures, is an endopeptidase. J Bacteriol. 1990 Apr;172(4):1791-7. PMID:2180903
- ↑ Kolmar H, Waller PR, Sauer RT. The DegP and DegQ periplasmic endoproteases of Escherichia coli: specificity for cleavage sites and substrate conformation. J Bacteriol. 1996 Oct;178(20):5925-9. PMID:8830688
- ↑ Spiess C, Beil A, Ehrmann M. A temperature-dependent switch from chaperone to protease in a widely conserved heat shock protein. Cell. 1999 Apr 30;97(3):339-47. PMID:10319814
- ↑ Krojer T, Pangerl K, Kurt J, Sawa J, Stingl C, Mechtler K, Huber R, Ehrmann M, Clausen T. Interplay of PDZ and protease domain of DegP ensures efficient elimination of misfolded proteins. Proc Natl Acad Sci U S A. 2008 Jun 3;105(22):7702-7. doi:, 10.1073/pnas.0803392105. Epub 2008 May 27. PMID:18505836 doi:10.1073/pnas.0803392105
- ↑ Pan KL, Hsiao HC, Weng CL, Wu MS, Chou CP. Roles of DegP in prevention of protein misfolding in the periplasm upon overexpression of penicillin acylase in Escherichia coli. J Bacteriol. 2003 May;185(10):3020-30. PMID:12730160
- ↑ Krojer T, Sawa J, Schafer E, Saibil HR, Ehrmann M, Clausen T. Structural basis for the regulated protease and chaperone function of DegP. Nature. 2008 Jun 12;453(7197):885-90. Epub 2008 May 21. PMID:18496527 doi:10.1038/nature07004
- ↑ Malet H, Canellas F, Sawa J, Yan J, Thalassinos K, Ehrmann M, Clausen T, Saibil HR. Newly folded substrates inside the molecular cage of the HtrA chaperone DegQ. Nat Struct Mol Biol. 2012 Jan 15;19(2):152-7. doi: 10.1038/nsmb.2210. PMID:22245966 doi:10.1038/nsmb.2210
|
