Project Details
Projekt
Interrogating DNA-centric bacterial defenses and phage counter-defenses
Applicant
Professor Dr. Chase Beisel
Subject Area
Metabolism, Biochemistry and Genetics of Microorganisms
Term
since 2021
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 465069819
The ongoing arms race between bacteria and (bacterio)phages has driven the evolution of a diverse range of bacterial defenses and phage-encoded anti-defenses, with each side constantly seeking to gain the upper hand. The past few years has witnessed an explosion in newly uncovered defenses and anti-defenses, yet almost all await experimental characterization. Through the first funding period, we endeavored to apply cell-free transcription-translation (TXTL) systems to interrogate novel defenses. These efforts resulted in mechanistic insights into membrane association by Zorya Type II defense systems as well as the discovery of an anti-CRISPR protein (AcrIC11) with homology to a long-known but poorly characterized anti-restriction protein (KlcA). We also began characterizing the poorly explored Druantia Type III systems and encountered flanking genes potentially representing a previously unreported defense. In the second funding period, we will build on these insights, our expertise in TXTL, and extensive preliminary data to advance our understanding of DNA-centric bacterial defenses and phage anti-defenses. In particular, we will pursue two hypothesis-driven research objectives: Objective 1: Elucidate how KlcA/AcrIC11 inhibits R-M systems and CRISPR-Cas systems. This objective is guided by the hypothesis that AcrIC11 and KlcA inhibit both Type I R-M systems and Type I-C CRISPR-Cas systems by directly interacting with nuclease subunits to block DNA translocation. Objective 2: Determine how Druantia Type III defense blocks phage infections. This objective is guided by the hypothesis that Druantia III prevents phage infections by cleavage of viral DNA through recognition of a free 3′ overhang, while Serket represents a novel anti-phage defense system requiring all four genes that confers resistance against epigenetically modified phages insensitive to Druantia III. If successful, this project will report and characterize an anti-defense protein capable of inhibiting multiple prevalent defenses despite the defenses sharing no common components. It will also provide mechanistic insights into poorly explored DNA-centric defenses. In turn, we expect to greatly expand our understanding of bacterial-phage interactions through their arsenal of defenses and counter-defenses.
DFG Programme
Priority Programmes
