Send to

Choose Destination
Sci Rep. 2016 Dec 7;6:38399. doi: 10.1038/srep38399.

A central cavity within the holo-translocon suggests a mechanism for membrane protein insertion.

Author information

European Molecular Biology Laboratory, Grenoble Outstation, 71 Avenue des Martyrs, 38042 Grenoble, France.
School of Biochemistry, University of Bristol, BS8 1TD, United Kingdom.
Department of Integrated Structural Biology, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), U964 INSERM, UMR7104 CNRS; University of Strasbourg, 1 Rue Laurent Fries, BP10142, 67404 Illkirch, France.
Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh, EH9 3JR, United Kingdom.
Department of Physics, University of Illinois Urbana Champaign, 3217 Beckman Institute, 405 N Mathews Ave., Urbana, IL 61801, USA.
Department of Bioanalytics, Institute of Biotechnology, Technische Universität Berlin, 13355 Berlin, Germany.
Institut Laue Langevin, 71 Avenue des Martyrs, F-38042 Grenoble, France.
CNRS, Institut de Biologie Structurale, F-38044 Grenoble, France.


The conserved SecYEG protein-conducting channel and the accessory proteins SecDF-YajC and YidC constitute the bacterial holo-translocon (HTL), capable of protein-secretion and membrane-protein insertion. By employing an integrative approach combining small-angle neutron scattering (SANS), low-resolution electron microscopy and biophysical analyses we determined the arrangement of the proteins and lipids within the super-complex. The results guided the placement of X-ray structures of individual HTL components and allowed the proposal of a model of the functional translocon. Their arrangement around a central lipid-containing pool conveys an unexpected, but compelling mechanism for membrane-protein insertion. The periplasmic domains of YidC and SecD are poised at the protein-channel exit-site of SecY, presumably to aid the emergence of translocating polypeptides. The SecY lateral gate for membrane-insertion is adjacent to the membrane 'insertase' YidC. Absolute-scale SANS employing a novel contrast-match-point analysis revealed a dynamic complex adopting open and compact configurations around an adaptable central lipid-filled chamber, wherein polytopic membrane-proteins could fold, sheltered from aggregation and proteolysis.

[Indexed for MEDLINE]
Free PMC Article

Publication type, MeSH terms, Substances, Grant support

Publication type

MeSH terms


Grant support

Supplemental Content

Full text links

Icon for Nature Publishing Group Icon for PubMed Central
Loading ...
Support Center