Preproteins couple the intrinsic dynamics of SecA to its ATPase cycle to translocate via a catch and release mechanism
Srinath Krishnamurthy,
Marios-Frantzeskos Sardis,
Nikolaos Eleftheriadis,
Katerina E. Chatzi,
Jochem H. Smit,
Konstantina Karathanou,
Giorgos Gouridis,
Athina G. Portaliou,
Ana-Nicoleta Bondar,
Spyridoula Karamanou,
Anastassios Economou
Affiliations
Srinath Krishnamurthy
KU Leuven, University of Leuven, Rega Institute, Department of Microbiology and Immunology, 3000 Leuven, Belgium
Marios-Frantzeskos Sardis
KU Leuven, University of Leuven, Rega Institute, Department of Microbiology and Immunology, 3000 Leuven, Belgium
Nikolaos Eleftheriadis
KU Leuven, University of Leuven, Rega Institute, Department of Microbiology and Immunology, 3000 Leuven, Belgium
Katerina E. Chatzi
KU Leuven, University of Leuven, Rega Institute, Department of Microbiology and Immunology, 3000 Leuven, Belgium
Jochem H. Smit
KU Leuven, University of Leuven, Rega Institute, Department of Microbiology and Immunology, 3000 Leuven, Belgium
Konstantina Karathanou
Freie Universität Berlin, Department of Physics, Theoretical Molecular Biophysics Group, Arnimallee 14, 14195 Berlin, Germany
Giorgos Gouridis
KU Leuven, University of Leuven, Rega Institute, Department of Microbiology and Immunology, 3000 Leuven, Belgium; Molecular Microscopy Research Group, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, the Netherlands; Structural Biology Division, Institute of Molecular Biology and Biotechnology (IMBB-FORTH), Nikolaou Plastira 100, Heraklion, Crete, Greece
Athina G. Portaliou
KU Leuven, University of Leuven, Rega Institute, Department of Microbiology and Immunology, 3000 Leuven, Belgium
Ana-Nicoleta Bondar
Freie Universität Berlin, Department of Physics, Theoretical Molecular Biophysics Group, Arnimallee 14, 14195 Berlin, Germany; University of Bucharest, Faculty of Physics, Atomiștilor 405, 077125 Măgurele, Romania; Forschungszentrum Jülich, Institute of Computational Biomedicine, IAS-5/INM-9, Wilhelm-Johnen Straße, 5428 Jülich, Germany
Spyridoula Karamanou
KU Leuven, University of Leuven, Rega Institute, Department of Microbiology and Immunology, 3000 Leuven, Belgium
Anastassios Economou
KU Leuven, University of Leuven, Rega Institute, Department of Microbiology and Immunology, 3000 Leuven, Belgium; Corresponding author
Summary: Protein machines undergo conformational motions to interact with and manipulate polymeric substrates. The Sec translocase promiscuously recognizes, becomes activated, and secretes >500 non-folded preprotein clients across bacterial cytoplasmic membranes. Here, we reveal that the intrinsic dynamics of the translocase ATPase, SecA, and of preproteins combine to achieve translocation. SecA possesses an intrinsically dynamic preprotein clamp attached to an equally dynamic ATPase motor. Alternating motor conformations are finely controlled by the γ-phosphate of ATP, while ADP causes motor stalling, independently of clamp motions. Functional preproteins physically bridge these independent dynamics. Their signal peptides promote clamp closing; their mature domain overcomes the rate-limiting ADP release. While repeated ATP cycles shift the motor between unique states, multiple conformationally frustrated prongs in the clamp repeatedly “catch and release” trapped preprotein segments until translocation completion. This universal mechanism allows any preprotein to promiscuously recognize the translocase, usurp its intrinsic dynamics, and become secreted.
