9PKQ
Structure of the cytoplasmic domain of unliganded human Tom70, open and closed conformations
Summary for 9PKQ
| Entry DOI | 10.2210/pdb9pkq/pdb |
| Descriptor | Mitochondrial import receptor subunit TOM70 (2 entities in total) |
| Functional Keywords | mitochondrion, receptor, preprotein, protein transport |
| Biological source | Homo sapiens (human) |
| Total number of polymer chains | 2 |
| Total formula weight | 115928.10 |
| Authors | Bachochin, M.J.,McGuire, K.L.,Cook, B.D.,Ye, Q.,Silletti, S.,Corbett, K.D.,Komives, E.A.,Herzik Jr., M.A. (deposition date: 2025-07-14, release date: 2026-03-18, Last modification date: 2026-03-25) |
| Primary citation | Bachochin, M.J.,McGuire, K.L.,Cook, B.D.,Ye, Q.,Silletti, S.,Corbett, K.D.,Komives, E.A.,Herzik Jr., M.A. An allosteric network governs Tom70 conformational dynamics to coordinate mitochondrial import. Structure, 34:273-, 2026 Cited by PubMed Abstract: Tom70 mediates mitochondrial protein import by coordinating transfer of cytosolic preproteins from Hsp70/Hsp90 to the translocase of the outer membrane (TOM) complex. In humans, the cytosolic domain of Tom70 (HsTom70c) is entirely α-helical and comprises modular TPR motifs divided into an N-terminal chaperone-binding and a C-terminal preprotein-binding domain. However, the mechanisms linking these functional regions remain poorly understood. Here, we present the 2.04 Å crystal structure of unliganded HsTom70c, revealing two distinct conformations-open and closed-within the asymmetric unit. These states are stabilized by interdomain crystal contacts and supported in solution by hydrogen-deuterium exchange mass spectrometry (HDX-MS) and molecular dynamics (MD) simulations. Principal component and network analyses reveal a continuum of motion linking the NTD and CTD via key residues in helices α7, α8, and α25. Engagement of the CTD by viral protein Orf9b disrupts this network, stabilizing a partially closed intermediate and dampening distal NTD dynamics. PubMed: 41386227DOI: 10.1016/j.str.2025.11.011 PDB entries with the same primary citation |
| Experimental method | X-RAY DIFFRACTION (2 Å) |
Structure validation
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