Technische Universität Braunschweig
  • Study & Teaching
    • Beginning your Studies
      • Prospective Students
      • Degree Programmes
      • Application
      • Fit4TU
      • Why Braunschweig?
    • During your Studies
      • Fresher's Hub
      • Term Dates
      • Courses
      • Practical Information
      • Beratungsnavi
      • Additional Qualifications
      • Financing and Costs
      • Special Circumstances
      • Health and Well-being
      • Campus life
    • At the End of your Studies
      • Discontinuation and Credentials Certification
      • After graduation
      • Alumni
    • For Teaching Staff
      • Strategy, Offers and Information
      • Learning Management System Stud.IP
    • Contact
      • Study Service Centre
      • Academic Advice Service
      • Student Office
      • Career Service
  • Research
    • Research Profile
      • Core Research Areas
      • Clusters of Excellence at TU Braunschweig
      • Research Projects
      • Research Centres
      • Professors‘ Research Profiles
    • Early Career Researchers
      • Support in the early stages of an academic career
      • PhD-Students
      • Postdocs
      • Junior research group leaders
      • Junior Professorship and Tenure-Track
      • Habilitation
      • Service Offers for Scientists
    • Research Data & Transparency
      • Transparency in Research
      • Research Data
      • Open Access Strategy
      • Digital Research Announcement
    • Research Funding
      • Research Funding Network
      • Research funding
    • Contact
      • Research Services
      • Academy for Graduates
  • International
    • International Students
      • Why Braunschweig?
      • Degree seeking students
      • Exchange Studies
      • TU Braunschweig Summer School
      • Refugees
      • International Student Support
      • International Career Service
    • Going Abroad
      • Studying abroad
      • Internships abroad
      • Teaching and research abroad
      • Working abroad
    • International Researchers
      • Welcome Support for International Researchers
      • Service for Host Institutes
    • Language and intercultural competence training
      • Learning German
      • Learning Foreign Languages
      • Intercultural Communication
    • International Profile
      • Internationalisation
      • International Cooperations
      • Strategic partnerships
      • International networks
    • International House
      • About us
      • Contact & Office Hours
      • News and Events
      • International Days
      • 5th Student Conference: Internationalisation of Higher Education
      • Newsletter, Podcast & Videos
      • Job Advertisements
  • TU Braunschweig
    • Our Profile
      • Aims & Values
      • Regulations and Guidelines
      • Alliances & Partners
      • The University Development Initiative 2030
      • Facts & Figures
      • Our History
    • Career
      • Working at TU Braunschweig
      • Vacancies
    • Economy & Business
      • Entrepreneurship
      • Friends & Supporters
    • General Public
      • Check-in for Students
      • CampusXperience
      • The Student House
      • Access to the University Library
    • Media Services
      • Communications and Press Service
      • Services for media
      • Film and photo permits
      • Advices for scientists
      • Topics and stories
    • Contact
      • General Contact
      • Getting here
  • Organisation
    • Presidency & Administration
      • Executive Board
      • Designated Offices
      • Administration
      • Committees
    • Faculties
      • Carl-Friedrich-Gauß-Fakultät
      • Faculty of Life Sciences
      • Faculty of Architecture, Civil Engineering and Environmental Sciences
      • Faculty of Mechanical Engineering
      • Faculty of Electrical Engineering, Information Technology, Physics
      • Faculty of Humanities and Education
    • Institutes
      • Institutes from A to Z
    • Facilities
      • University Library
      • Gauß-IT-Zentrum
      • Professional and Personnel Development
      • International House
      • The Project House of the TU Braunschweig
      • Transfer Service
      • University Sports Center
      • Facilities from A to Z
    • Equal Opportunity Office
      • Equal Opportunity Office
      • Family
      • Diversity for Students
  • Search
  • Quicklinks
    • People Search
    • Webmail
    • cloud.TU Braunschweig
    • Messenger
    • Cafeteria
    • Courses
    • Stud.IP
    • Library Catalogue
    • IT Services
    • Information Portal (employees)
    • Link Collection
    • DE
    • EN
    • Bluesky
Menu
  • Organisation
  • Faculties
  • Faculty of Life Sciences
  • Institutes
  • Physical and Theoretical Chemistry
  • WG Walla
  • Research
Logo Institut für Physikalische und Theoretische Chemie der TU Braunschweig

Membrane Docking and Fusion Assay

Membrane fusion is pivotal in many processes like synaptic signal transmission but also membrane trafficking, viral entry or fertilization. These processes are regulated by various proteins with SNARES (soluble N-ethylmaleimide-sensitive factor attachment protein receptors) being very important catalysts for this process. However, prior to fusion important intermediate states occur that are presumably decisive for the general regulation of membrane interactions. For example, pre-docked states exist in which the membranes are tethered by certain proteins but are not yet fused. Such states might be pivotal to allow for quick triggering of the actual fusion event.

Docking scheme
Figure 1

In order to investigate the mechanism by which various types of proteins regulate docking and fusion assays are necessary that are able to distinguish non-interacting membranes from docked and fused states. To this end, liposome model systems are particular useful as they allow to selectively investigate the different roles of individual key players reconstituted into two different sets of liposomes representing the two interacting membranes. Therefore, we have developed a liposome assay based on single liposome detection, two-photon two-color fluorescence cross-correlation spectroscopy and fluorescence lifetime measurements that allows to differentiate individual free, docked or fused liposomes or quantify the number of free, docked or fused liposomes in a confocal detection volume of a microscope set-up.

We have developed a liposome assay based on single liposome detection, two-photon two-color fluorescence cross-correlation spectroscopy and fluorescence lifetime measurements that allows to differentiate individual free, docked or fused liposomes or quantify the number of free, docked or fused liposomes in a confocal detection volume of a microscope set-up.
Figure 2

The assay is based on labelling the lipids of two different sets of liposomes with two different dyes. The two different sets of liposomes can contain different proteins, can have different lipid compositions and different membrane curvatures as differing diameters down to ~30 nm are possible. The two dyes can emit, for example, fluorescence in the red and green spectral range. In a two-photon excitation microscope an excitation wavelength can be selected that excites both dyes to approximately the same extend when liposomes diffuse through the excitation volume of about 200-300 nm in diameter. Non-interacting liposomes are detected as independent fluorescence signals in the red and green detector channel of the microscope set-up. If liposomes are docked or fused, the red and green fluorescence signals are detected in a correlated manner. In addition, if the liposomes are fused, Förster energy transfer occurs within the lipid bilayers leading to a reduction of the green fluorescence emission and an increase in the red fluorescence emission. In order to quantify the percentage of docked or fused liposomes diffusing through the detection volume two-photon, two-color fluorescence cross-correlation spectroscopy is applied. For robust determination of the degree of lipid mixing (fusion) in a sample, simultaneously the fluorescence lifetime of the donor molecules is recorded.

Docking Scheme
Figure 3

[1] A. Cypionka , A. Stein , J. M. Hernandez , H. Hippchen , R. Jahn , P. J. Walla "Discrimination between docking and fusion of liposomes reconstituted with neuronal SNARE-proteins using FCS", PNAS, 106, 44, 18575-18580 (2009).
[2] J. M. Hernandez, A. Stein, E. Behrmann, D. Riedel, A. Cypionka, Z. Farsi, P. J. Walla, S. Raunser and R. Jahn,"Membrane Fusion Intermediates via Directional and Full Assembly of the SNARE Complex", Science, 336, 1581-1584 (2012).
[3] W. Vennekate, S. Schröder, C.-C. Lin, G. van den Bogaart, M. Grunwald, R. Jahn, P. J. Walla,"Cis- and trans-membrane interactions of synaptotagmin-1", PNAS, 109, 11037-11042 (2012).
[4] C.-C. Lin, H.-F. Hsu, P.J. Walla, " A One Donor-Two Acceptor Lipid Bilayer FRET Assay Based on Asymmetrically Labeled Liposomes " J. Phys. Chem. B. , accepted (2016)

 

Photo credits on this page

Research

Research Groups
Bauerecker Group
Hohm Group 
Jacob Group
Maul Group
Proppe Group
Tschierlei Group 
Walla Group

Associated Groups
Muñoz Group (GRS)

Emeriti
Becker Group
Gericke Group

Institute

Personnel
Institute Director
Executive Board
Staff

Facilities
Workshop
School lab (G)
Agnes Pockels lab

Documents
Institute Rules (G)
Operation Manuals
Laser safety
Emergency leaflet

 

Service

Campus Map (G)
Events Calendar (G)
TU Public Announcements
Whistle Blowing (G)

Ticket GITZ (G)
Ticket Facilities Management (G)
Energy Web Portal (G)

(G) German only

Contact

Technische Universität Braunschweig
Institute of Physical und Theoretical Chemistry

Gaußstraße 17
38106 Braunschweig
P. O. Box 3329
38023 Braunschweig
Germany
Phone +49 531 3915325

In case of emergency

© Technische Universität Braunschweig
Legal Notice Privacy Accessibility

TU Braunschweig uses the software Matomo for anonymised web analysis. The data serve to optimise the web offer.
You can find more information in our data protection declaration.