(III) Outer membrane biogenesis in Gram-negative bacteria – protein-protein interactions as target sites for small molecule inhibitors

Tracking evolutionary variation among protein machineries based on their mechanistic heterogeneity in biological systems is an unconventional approach that goes further than traditional sequence and structure-based protein-to-protein comparisons. A well understood essential and fascinating mechanism that has attracted much of attention recently as essential component for the maturation of outer membrane proteins (OMPs). OMP biogenesis is a complex and sophisticated multistep process, whereby a preprotein in a chaperoned form is targeted to the insertase complex, transferred there, and folded at this scaffold before being released into the membrane as an active protein. This mechanism is striking, as proteins are translocated and folded in the absence of energy. The mechanistic basis developed in ancient bacteria has been conserved throughout evolution and is also maintained in eukaryotic organelles after endosymbiosis. This process is exciting to study since it functionally combines a protein complex, consisting of an essential and conserved receptor component of the Omp85/BamA superfamily, with divergent adaptor proteins at the periphery of insertase complexes.

Ultimately, our investigations aim to furnish a detailed mechanistic description of the principles governing OMP biogenesis, a ubiquitous process of nature. Due to their essential nature, exploring the structure and mechanisms of the BAM complex in Gram- negative bacteria has strong implications for pharmaceutical studies. The association between this complex and bacterial pathogenicity can lead to the development of small molecules that block these processes, thereby helping to treat infectious diseases. Recently we identified small decapeptides derived from BamA with an unusually low MIC in growth assays of E. coli and Neisseria. In later steps, small molecule docking and the implementation of tests to measure the effectiveness could help to identify molecules that target the essential BamA and BamD scaffolds. In collaboration with companies we aim to introduce these peptides into a pharmaceutical pipeline and establish an integrated drug discovery program.