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Journal Articles Scientific Reports Year : 2017

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

Rémy Martin
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  • PersonId : 857663
Giuseppe Zaccai
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  • PersonId : 843908

Abstract

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
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Dates and versions

hal-01597707 , version 1 (24-01-2018)

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Mathieu Botte, Nathan R. Zaccai, Jelger Lycklama À. Nijeholt, Rémy Martin, Kèvin Knoops, et al.. A central cavity within the holo-translocon suggests a mechanism for membrane protein insertion. Scientific Reports, 2017, 6 (38399), 13 p. ⟨10.1038/srep38399⟩. ⟨hal-01597707⟩
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