2qgr
From Proteopedia
Structure of the R178A mutant of delta PDZ DegS protease
Structural highlights
FunctionDEGS_ECOLI When heat shock or other environmental stresses disrupt protein folding in the periplasm, DegS senses the accumulation of unassembled outer membrane porins (OMPs) and then initiates RseA (anti sigma-E factor) degradation by cleaving it in its periplasmic domain, making it an attractive substrate for subsequent cleavage by RseP. This cascade that ultimately leads to the sigma-E-driven expression of a variety of factors dealing with folding stress in the periplasm and OMP assembly.[1] [2] 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 PubMedRegulated intramembrane proteolysis is a method for transducing signals between cellular compartments. When protein folding is compromised in the periplasm of E. coli, the C termini of outer-membrane proteins (OMPs) bind to the PDZ domains of the trimeric DegS protease and activate cleavage of RseA, a transmembrane transcriptional regulator. We show here that DegS is an allosteric enzyme. OMP binding shifts the equilibrium from a nonfunctional state, in which the active sites are unreactive, to the functional proteolytic conformation. Crystallographic, biochemical, and mutagenic experiments show that the unliganded PDZ domains are inhibitory and suggest that OMP binding per se is sufficient to stabilize the relaxed conformation and activate DegS. OMP-induced activation and RseA binding are both positively cooperative, allowing switch-like behavior of the OMP-DegS-RseA system. Residues involved in the DegS allosteric switch are conserved in the DegP/HtrA and HtrA2/Omi families, suggesting that many PDZ proteases use a common mechanism of allosteric activation. Allosteric activation of DegS, a stress sensor PDZ protease.,Sohn J, Grant RA, Sauer RT Cell. 2007 Nov 2;131(3):572-83. PMID:17981123[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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