3sti

Crystal structure of the protease domain of DegQ from Escherichia coli

spinqualitylabelsall models 3sti, resolution 2.60Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3sti is a 3 chain structure with sequence from Ecoli. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Related: 3stj Gene: degQ, hhoA, b3234, JW3203 (ECOLI) Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [DEGQ_ECOLI] DegQ could degrade transiently denatured and unfolded proteins which accumulate in the periplasm following stress conditions. DegQ is efficient with Val-Xaa and Ile-Xaa peptide bonds, suggesting a preference for a beta-branched side chain amino acids. Only unfolded proteins devoid of disulfide bonds appear capable to be cleaved, thereby preventing non-specific proteolysis of folded proteins. DegQ can substitute for the periplasmic protease DegP. Publication Abstract from PubMed In order to react on distinct stress situations and to prevent the accumulation of misfolded proteins, all cells employ a number of proteases and chaperones, which together setup an efficient protein quality control system. The functionality of proteins in the cell envelope of E.coli is monitored by the HtrA proteases DegS, DegP and DegQ. In contrast to DegP and DegS, the structure and function of DegQ has not been addressed in detail. Here, we show that substrate binding triggers the conversion of the resting DegQ hexamer into catalytically active 12- and 24-mers. Interestingly, substrate-induced oligomer reassembly and protease activation depends on the first PDZ domain, but not on the second. Therefore, the regulatory mechanism originally identified in DegP should be a common feature of HtrA proteases, most of which encompass only a single PDZ domain. Using a DegQ mutant lacking the second PDZ domain we determined the high-resolution crystal structure of a dodecameric HtrA complex. The nearly identical domain orientation of protease and PDZ domains within 12- and 24-meric HtrA complexes reveals a conserved PDZ1-->L3-->LD/L1/L2 signaling cascade, in which loop L3 senses the repositioned PDZ1 domain of higher-order, substrate engaged particles and activates protease function. Furthermore, our in vitro and in vivo data imply a pH-related function of DegQ in the bacterial cell envelope. Molecular adaptation of the DegQ protease to exert protein quality control in the bacterial cell envelope.,Sawa J, Malet H, Krojer T, Canellas F, Ehrmann M, Clausen T J Biol Chem. 2011 Jun 17. PMID:21685389 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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