title: Membrane protein insertion and proton-motive-force-dependent secretion through the bacterial holo-translocon SecYEG-SecDF-YajC-YidC.
abstract: The SecY/61 complex forms the protein-channel component of the ubiquitous protein secretion and membrane protein insertion apparatus. The bacterial version SecYEG interacts with the highly conserved YidC and SecDF-YajC subcomplex, which facilitates translocation into and across the membrane. Together, they form the holo-translocon (HTL), which we have successfully overexpressed and purified. In contrast to the homo-dimeric SecYEG, the HTL is a hetero-dimer composed of single copies of SecYEG and SecDF-YajC-YidC. The activities of the HTL differ from the archetypal SecYEG complex. It is more effective in cotranslational insertion of membrane proteins and the posttranslational secretion of a β-barreled outer-membrane protein driven by SecA and ATP becomes much more dependent on the proton-motive force. The activity of the translocating copy of SecYEG may therefore be modulated by association with different accessory subcomplexes: SecYEG (forming SecYEG dimers) or SecDF-YajC-YidC (forming the HTL). This versatility may provide a means to refine the secretion and insertion capabilities according to the substrate. A similar modularity may also be exploited for the translocation or insertion of a wide range of substrates across and into the endoplasmic reticular and mitochondrial membranes of eukaryotes.
authors.affiliation: School of Biochemistry, University of Bristol, Bristol BS8 1TD, United Kingdom.
authors.forename: Ryan J
authors.initials: RJ
authors.lastname: Schulze
authors.forename: Joanna
authors.initials: J
authors.lastname: Komar
authors.forename: Mathieu
authors.initials: M
authors.lastname: Botte
authors.forename: William J
authors.initials: WJ
authors.lastname: Allen
authors.forename: Sarah
authors.initials: S
authors.lastname: Whitehouse
authors.forename: Vicki A M
authors.initials: VA
authors.lastname: Gold
authors.forename: Jelger A
authors.initials: JA
authors.lastname: Lycklama A Nijeholt
authors.forename: Karine
authors.initials: K
authors.lastname: Huard
authors.forename: Imre
authors.initials: I
authors.lastname: Berger
authors.forename: Christiane
authors.initials: C
authors.lastname: Schaffitzel
authors.forename: Ian
authors.initials: I
authors.lastname: Collinson
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D003432:Cross-Linking Reagents / Q000378:metabolism; D004926:Escherichia coli / Q000187:drug effects / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000302:isolation & purification / Q000378:metabolism*; D008565:Membrane Proteins / Q000302:isolation & purification / Q000378:metabolism*; D008954:Models, Biological; D046912:Multiprotein Complexes / Q000378:metabolism*; D011485:Protein Binding / Q000187:drug effects; D055550:Protein Stability / Q000187:drug effects; D021122:Protein Subunits / Q000378:metabolism; D021381:Protein Transport / Q000187:drug effects; D018892:Proton-Motive Force / Q000187:drug effects; D012270:Ribosomes / Q000187:drug effects / Q000378:metabolism
chemical_list: D003432:Cross-Linking Reagents; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D046912:Multiprotein Complexes; D021122:Protein Subunits; D000255:Adenosine Triphosphate