10et

Chloroplast Glutamyl Peptidase D855N in open-closed conformation

spinqualitylabelsall models 10et, resolution 3.00Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 10et is a 2 chain structure with sequence from Arabidopsis thaliana. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: Electron Microscopy, Resolution 3Å Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function CGEP_ARATH Serine-type protease active in vitro against the LHCII N-terminal. Cleaves its substrate on the carboxy-side of Glu residues (By similarity).[REFERENCE:4] Publication Abstract from PubMed S9 proteases are widely distributed across the tree-of-life and play essential roles in protein processing. However, the structural and mechanistic basis for protease activity in the S9D subfamily, restricted to photosynthetic eukaryotes (e.g., plants), cyanobacteria, proteobacteria and flavobacteria, is unknown. Here, we report the first high-resolution cryo-EM structures of an S9D protease, chloroplast glutamyl endopeptidase (CGEP) from the model plant Arabidopsis thaliana. CGEP adopts a dimeric architecture stabilized by two distinct interfaces: hydrophobic interactions between catalytic domains and an interdomain beta-sheet linking the cap and catalytic domains. These interactions create a scaffold that supports a hinge loop, which acts as a steric gate to restrict substrate access and confine catalytic activity to the closed conformation. Unlike S9A-B-C proteases, CGEP maintains an intact catalytic triad in both open and closed states, relying on hinge-loop gating rather than catalytic disruption for regulation. Structural analysis and mutagenesis reveal that the hinge loop forms a conserved pocket favoring glutamate side chains, explaining CGEP's strong glutamate preference at cleavage sites. Together, these findings uncover a unique regulatory paradigm for S9D proteases and provide a structural framework for understanding substrate selectivity and dimerization. Structural basis for dimerization, catalytic regulation, and substrate selectivity of the chloroplast S9D CGEP protease in Arabidopsis thaliana.,Ehrlich JJ, Routray P, Enns L, van Wijk KJ, Kawate T Protein Sci. 2026 Jun;35(6):e70624. doi: 10.1002/pro.70624. PMID:42144868 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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