Download MendeleyAn allosteric network governs Tom70 conformational dynamics to coordinate mitochondrial import.
Bachochin, M.J., McGuire, K.L., Cook, B.D., Ye, Q., Silletti, S., Corbett, K.D., Komives, E.A., Herzik Jr., M.A.(2026) Structure 34: 273
- PubMed: 41386227
- DOI: https://doi.org/10.1016/j.str.2025.11.011
- Primary Citation Related Structures:
9PKQ - 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.
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093, USA.
Organizational Affiliation:
