Directed Evolution of Protein Materials

Natural proteins continuously evolve in a direction that optimizes the fitness of the organism. “Evolution-in-a-test-tube” (also known as directed evolution) is highly successful for improving enzymes, and for finding proteins that bind to selected targets. But can we also use directed evolution to make new protein materials? So far, this is an outstanding challenge because nobody knows how to do screening of material properties for proteins produced by a library of bacteria. The problem is that you need to screen the protein material properties at the single cell level. In order to work towards directed evolution of protein materials, we can start with an example for which we might be able to screen material properties at the single cell level. One such example is the so-called structural amyloids of bacteria: these are proteins that assemble into beta-sheet rich fibrils on the outside of bacteria, and which are part of the “biofilm-forming” substances produced by many bacteria. At this stage, this project is still in an exploratory phase: First, you will conduct some proof of principle experiments. We have in mind to first try to visualize how the fibrils grow on individual bacteria, for many bacteria at the same time. This would already allow us to sort out varieties of the fibrils that grow fast or slow. The project will be together with Johannes Hohlbein at Biophysics (BIP), who will provide access to TIRF-based super-resolution microscope allowing to get very detailed fluorescent images of the growing fibrils.

Techniques: Basic molecular biology (handling E. coli cells), Bio-conjugating Fluorescent Moieties to CsgA fibrils, TIRF microscopy, Super-resolution Microscopy.