9sx3

Middle domain of HSP90C from Arabidopsis thaliana

spinqualitylabelsall models 9sx3, resolution 3.01Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 9sx3 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: X-ray diffraction, Resolution 3.01Å Ligands: SO4 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function HS905_ARATH Molecular chaperone required for chloroplast biogenesis (PubMed:12943545, PubMed:25216779). Essential for chloroplast biogenesis and maintenance, and thus for embryogenesis (PubMed:23382192, PubMed:23875936). May be involved in the disassembly of VIPP1 for thylakoid membrane formation and/or maintenance (PubMed:23875936). Cooperates with TIC components and other molecular chaperones to drive transport of preproteins into chloroplasts and functions in the chloroplast stroma to facilitate membrane translocation during protein import into the organelle (PubMed:23382192). Publication Abstract from PubMed Chloroplasts are the main energy-producing organelles in plants, responsible for photosynthesis, CO(2) fixation, and O(2) production. These processes rely on the import of numerous nucleus-encoded proteins into the chloroplast and, eventually, the thylakoids. While translocation systems across chloroplast and thylakoid membranes are well characterized, the stromal route between these membranes remains poorly understood. The chloroplastic HSP90 (HSP90C) is likely to play a key role in this process, yet its structure and molecular mechanisms are unknown. Here, we combine structural and biophysical approaches to characterize HSP90C from Arabidopsis thaliana. We show that HSP90C displays exceptionally high ATPase activity compared with other HSP90 family members, driven by non-canonical mechanisms. These include an N-terminal disulfide bond that enhances ATPase activity and a C-terminal extension required for dimerization. These features arise from conserved sequence signatures shared among Angiospermae. Our work provides the first structural insights into HSP90C and advances understanding of chloroplast protein import mechanisms. Structural basis of HSP90C, a highly active chloroplastic HSP90 chaperone from Arabidopsis thaliana.,La Rocca R, Chenuel T, Bergonzi C, Maes A, Pozza A, Meyer P J Mol Biol. 2026 Jul 6;438(19):169935. doi: 10.1016/j.jmb.2026.169935. PMID:42409278 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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