Two copies of the SecY channel and acidic lipids are necessary to activate the SecA translocation ATPase

Kush Dalal, Catherine S. Chan, Stephen G. Sligar, Franck Duong

Research output: Contribution to journalArticlepeer-review

Abstract

The SecA ATPase associates with the SecY complex to push preproteins across the bacterial membrane. Because a single SecY is sufficient to create the conducting channel, the function of SecY oligomerization remains unclear. Here, we have analyzed the translocation reaction using nanodiscs. We show that one SecY copy is sufficient to bind SecA and the preprotein, but only the SecY dimer together with acidic lipids supports the activation of the SecA translocation ATPase. In discs, the dimer is predominantly arranged in a back-to-back manner and remains active even if a constituent SecY copy is defective for SecA binding. In membrane vesicles and in intact cells, the coproduction of two inactive SecYs, one for channel gating and the other for SecA binding, recreates a functional translocation unit. These results indisputably argue that the SecY dimer is crucial for the activation of SecA, which is necessary for preprotein transport.

Original languageEnglish (US)
Pages (from-to)4104-4109
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume109
Issue number11
DOIs
StatePublished - Mar 13 2012

Keywords

  • Membrane transporters
  • Nanolipoparticles
  • SecYEG channel

ASJC Scopus subject areas

  • General

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