Proteins in the outer membranes of Gram-negative bacteria and mitochondria are responsible for essential cellular functions, including transport, respiration, signal transduction, and catalysis. The outer membrane proteins (Omps) are synthesized in the cytosol of the cell and transported in an unfolded form to the respective target membrane. For the transport across the aqueous compartments along this pathway, the Omps are stabilized by chaperones. From these chaperone-bound states the proteins fold into the lipid bilayer, catalyzed by large β-barrel assembly machineries with central units from the Omp85 family of proteins. As a general goal of our work, we want to understand the molecular mechanisms underlying the Omp biogenesis at the atomic level. In the framework of the SNSF professorship prolongation, I want to focus on three particular aspects of this process, as defined below in projects A–C. Our main technique is nuclear magnetic resonance (NMR) spectroscopy, which we use together with complementary techniques to address our research questions. The development of improved NMR technology is thus an integral part of our activities. Such techniques are applicable to our membrane protein systems of interest but will also stimulate NMR research on other challenging biomacromolecular systems. Project A: Investigation of conformation and dynamics of SecB–Omp and trigger-factor–Omp complexes. We will establish biophysical descriptions of these two chaperones and of Omp substrates in complex with these chaperones by solution NMR spectroscopy. Preliminary data shows that we can handle the biochemistry of these systems well and can thus obtain high-quality NMR spectra. These studies will substantially contribute to understanding principles of chaperone function. Project B: Elucidation of the functional mechanism of the large β-barrel assembly machineries from the Omp85 proteins, Bam and Tam. We have previously determined the structure of the autotransporter translocase TamA and now we want to understand at the atomic level how folding and insertion of proteins into the membrane is accomplished. The mechanisms of Omp85 proteins are essential functions for Gram-negative bacteria and mitochondria. Project C: Biophysical studies to describe the in vitro folding mechanisms of β-barrel outer membrane folding and its modulation by external parameters. We have developed a setup for proton–deuterium exchange during Omp refolding and will use this setup to study the folding process at the atomic level. These research studies will contribute fundamental aspects the biophysics of membrane protein folding.