The mechanism of protein export enhancement by the SecDF membrane component

• Tsukazaki Tomoya

  Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo

• Nureki Osamu

  Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo

Abstract

Protein transport across membranes is a fundamental and essential cellular activity in all organisms. In bacteria, protein export across the cytoplasmic membrane, driven by dynamic interplays between the protein-conducting SecYEG channel (Sec translocon) and the SecA ATPase, is enhanced by the proton motive force (PMF) and a membrane-integrated Sec component, SecDF. However, the structure and function of SecDF have remained unclear. We solved the first crystal structure of SecDF, consisting of a pseudo-symmetrical 12-helix transmembrane domain and two protruding periplasmic domains. Based on the structural features, we proposed that SecDF functions as a membrane-integrated chaperone, which drives protein movement without using the major energetic currency, ATP, but with remarkable cycles of conformational changes, powered by the proton gradient across the membrane. By a series of biochemical and biophysical approaches, several functionally important residues in the transmembrane region have been identified and our model of the SecDF function has been verified.<br>

Journal

• BIOPHYSICS

  BIOPHYSICS 7 129-133, 2011

  The Biophysical Society of Japan

Keywords

• Sec translocon
• SecDF
• protein transport

Details

• CRID: 1390001205223895552
• NII Article ID: 130001253088
• DOI: 10.2142/biophysics.7.129
• ISSN: 13492942
• Web Site: http://www.jstage.jst.go.jp/article/biophysics/7/0/7_0_129/_pdf
• Text Lang: en
• Data Source:
  • JaLC
  • Crossref
  • CiNii Articles
• Abstract License Flag: Disallowed