1ky9
From Proteopedia
Crystal Structure of DegP (HtrA)
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] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedMolecular chaperones and proteases monitor the folded state of other proteins. In addition to recognizing non-native conformations, these quality control factors distinguish substrates that can be refolded from those that need to be degraded. To investigate the molecular basis of this process, we have solved the crystal structure of DegP (also known as HtrA), a widely conserved heat shock protein that combines refolding and proteolytic activities. The DegP hexamer is formed by staggered association of trimeric rings. The proteolytic sites are located in a central cavity that is only accessible laterally. The mobile side-walls are constructed by twelve PDZ domains, which mediate the opening and closing of the particle and probably the initial binding of substrate. The inner cavity is lined by several hydrophobic patches that may act as docking sites for unfolded polypeptides. In the chaperone conformation, the protease domain of DegP exists in an inactive state, in which substrate binding in addition to catalysis is abolished. Crystal structure of DegP (HtrA) reveals a new protease-chaperone machine.,Krojer T, Garrido-Franco M, Huber R, Ehrmann M, Clausen T Nature. 2002 Mar 28;416(6879):455-9. PMID:11919638[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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