Katharina Wandera       email
Helmholtz Institute for RNA-based Infection Research

Supervisor:

Prof. Dr. Chase Beisel  (Würzburg)

Promotion Committee:
Prof. Dr. Chase Beisel  (Würzburg)
PD Dr. Knut Ohlsen (Würzburg)
Prof. Dr. Lars Barquist (Würzburg)
Prof. Dr. Peter Fineran (Otago)

Identification and Characterization of anti-CRISPR proteins

CRISPR-Cas systems were originally described as a part of the immune system of bacteria, but with time gave rise to one of the most important biotechnological genome-editing tools to-date. The characterization of CRISPR-Cas immune systems in bacteria was quickly followed by the discovery of anti-CRISPR proteins (Acrs) in bacteriophages. These proteins block different steps of CRISPR-based immunity and, as some inhibit Cas nucleases, can offer tight control over CRISPR technologies. Currently, only a handful of Acrs have been discovered against a small fraction of CRISPR-Cas systems while many more Acrs likely exist against the multitude of Cas nucleases in nature.

My work focuses on characterizing putative Acrs against Cas nucleases using an E. coli-derived cell-free transcription-translation system (TXTL). We developed a rapid and scalable method which enables us to characterize putative Acrs in under two days. The method was demonstrated using known Acrs against Cas9 as models. From there, we use machine learning approaches to identify Acr candidates and test these in our cell-free system. This enables us to screen large sets of putative Acrs, providing a basis for further biochemical characterization and the application of Acrs for controlling CRISPR technologies.