YidC Occupies the Lateral Gate of the SecYEG Translocon and Is Sequentially Displaced by a Nascent Membrane Protein |
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Authors: | Ilie Sachelaru Narcis Adrian Petriman Renuka Kudva Patrick Kuhn Thomas Welte Bettina Knapp Friedel Drepper Bettina Warscheid Hans-Georg Koch |
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Institution: | From the ‡Institut für Biochemie und Molekularbiologie, ZBMZ, ;§Fakultät für Biologie, ;the ¶Spemann Graduate School of Biology and Medicine (SGBM), and ;the ‖BIOSS Centre for Biological Signalling Studies, Zentrum für Biologische Signalstudien, Albert-Ludwigs-Universität Freiburg, 79104 Freiburg, Germany |
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Abstract: | Most membrane proteins are co-translationally inserted into the lipid bilayer via the universally conserved SecY complex and they access the lipid phase presumably via a lateral gate in SecY. In bacteria, the lipid transfer of membrane proteins from the SecY channel is assisted by the SecY-associated protein YidC, but details on the SecY-YidC interaction are unknown. By employing an in vivo and in vitro site-directed cross-linking approach, we have mapped the SecY-YidC interface and found YidC in contact with all four transmembrane domains of the lateral gate. This interaction did not require the SecDFYajC complex and was not influenced by SecA binding to SecY. In contrast, ribosomes dissociated the YidC contacts to lateral gate helices 2b and 8. The major contact between YidC and the lateral gate was lost in the presence of ribosome nascent chains and new SecY-YidC contacts appeared. These data demonstrate that the SecY-YidC interaction is influenced by nascent-membrane-induced lateral gate movements. |
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Keywords: | Membrane Biogenesis Membrane Trafficking Protein Targeting Secretion Signal Recognition Particle |
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