title: Probing the SecYEG translocation pore size with preproteins conjugated with sizable rigid spherical molecules.
abstract: Protein translocation in Escherichia coli is mediated by the translocase that in its minimal form consists of the protein-conducting channel SecYEG, and the motor protein, SecA. SecYEG forms a narrow pore in the membrane that allows passage of unfolded proteins only. Molecular dynamics simulations suggest that the maximal width of the central pore of SecYEG is limited to . To access the functional size of the SecYEG pore, the precursor of outer membrane protein A was modified with rigid spherical tetraarylmethane derivatives of different diameters at a unique cysteine residue. SecYEG allowed the unrestricted passage of the precursor of outer membrane protein A conjugates carrying tetraarylmethanes with diameters up to , whereas a sized molecule blocked the translocation pore. Translocation of the protein-organic molecule hybrids was strictly proton motive force-dependent and occurred at a single pore. With an average diameter of an unfolded polypeptide chain of , the pore accommodates structures of at least , which is vastly larger than the predicted maximal width of a single pore by molecular dynamics simulations.
authors.affiliation: Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, Nijenborgh 7, 9747 AG Groningen, The Netherlands.
authors.forename: Francesco
authors.initials: F
authors.lastname: Bonardi
authors.forename: Erik
authors.initials: E
authors.lastname: Halza
authors.forename: Martin
authors.initials: M
authors.lastname: Walko
authors.forename: François
authors.initials: F
authors.lastname: Du Plessis
authors.forename: Nico
authors.initials: N
authors.lastname: Nouwen
authors.forename: Ben L
authors.initials: BL
authors.lastname: Feringa
authors.forename: Arnold J M
authors.initials: AJ
authors.lastname: Driessen
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D056004:Molecular Dynamics Simulation; D015394:Molecular Structure; D011487:Protein Conformation; D011498:Protein Precursors / Q000737:chemistry / Q000378:metabolism; D021381:Protein Transport; D018892:Proton-Motive Force; D000069816:SEC Translocation Channels; D000081416:SecA Proteins
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D026901:Membrane Transport Proteins; D011498:Protein Precursors; D000069816:SEC Translocation Channels; D000251:Adenosine Triphosphatases; D000081416:SecA Proteins