Meet Inspiring Speakers and Experts at our 3000+ Global Conference Series Events with over 1000+ Conferences, 1000+ Symposiums
and 1000+ Workshops on Medical, Pharma, Engineering, Science, Technology and Business.

Explore and learn more about Conference Series : World's leading Event Organizer

Back

Andreas Kuhn

Andreas Kuhn

University of Hohenheim, Germany

Title: The dynamics of a protein during its insertion into a membrane

Biography

Biography: Andreas Kuhn

Abstract

Most membrane proteins are inserted co-translationally by the Sec-translocase or the YidC/Oxa1/Alb3 insertases. The folding of these proteins occurs within the membrane during the interaction with the insertases. We have purified and reconstituted YidC, the membrane insertase of Escherichia coli. The protein spans the membrane 6 times, and the recently solved structure shows a hydrophilic cavity and a greasy slide between the transmembrane segments TM3 and TM5. Hydrophobic residues of TM3 and TM5 interact with the substrate, in particular with a prospective transmembrane segment of an inserting membrane protein as we documented by disulfide crossinking experiments.

The membrane insertion process can be studied with the reconstituted vesicle system. The purified substrate proteins are solubilized in 10% isopranol or kept unfolded with urea or GuHCl. When the substrate proteins are added to the proteoliposomes by dilution 1:100, they rapidly bind to YidC and become membrane inserted within 2 msec. FRET-based kinetic measurements show that the substrate proteins approach YidC to a close distance during the insertion event. Time-resolved fluorenscence anisotropy shows that the periplasmic domain of YidC moves when a substrate protein was added. This suggests that both the insertase and the substrate protein undergo conformational motions.

References:

  1. Winterfeld, S., S. Ernst, M. Börsch, U. Gerken and A. Kuhn (2013). Real time observation of single membrane protein insertion events by the E. coli insertase YidC.  PLOSone 8, e59023.
  2. Dalbey, R.E. and A. Kuhn A. (2014) How YidC inserts and folds proteins across a membrane. Nature Struc.& Mol.Biol. 21, 435-436.
  3. Dalbey, R. E. and A. Kuhn (2015). Membrane insertases are present in all three domains of life. Structure 23, 1559-1560.
  4. Proß, E., L. Soussoula, I. Seitl, D. Lupo and A. Kuhn (2016). Membrane targeting and insertion of the C-tail protein SciP. J. Mol. Biol. 428, 4218-4227.
  5. Kuhn, A. and R.E. Dalbey (2016). A conformational crosstalk between SecA and SecY opens the SecYEG channel. Current Biol. 26, 811-813.