Open Readings 2023 • P3-63
STRUCTURAL AND FUNCTIONAL STUDIES OF THOERIS ANTIPHAGE DEFENSE SYSTEM
Dziugas Sabonis1, Giedrius Sasnauskas1, Audrone Ruksenaite1, Arunas Silanskas1, Gal Ofir2, Rotem Sorek2, Mindaugas Zaremba1, Virginijus Siksnys1, Giedre Tamulaitiene1
1 Institute of Biotechnology, Life Sciences Center, Vilnius University, Saulėtekio av. 7, LT-10257, Vilnius, Lithuania.
2 Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel.
[email protected]
Prokaryotic antiviral (antiphage) defense system research is a rapidly developing field. In recent years, known arsenal of antiphage systems has expanded to over a hundred of confirmed unique instances [1]. Detailed investigation of these systems reveals unique molecular pathways and deepens our knowledge about microorganism ecology. However, only a small number of antiphage systems are characterized in depth.
Thoeris is a bacterial antiviral defense system composed of two genes thsA and thsB. ThsB protein contains Toll/interleukin-1 receptor (TIR) domain which is a canonical component of animal and plant immune systems. ThsA is composed of a sirtuin-like (SIR2) and SLOG domains [2]. Representative structures of ThsA and ThsB proteins and their functional studies were published recently [3, 4]. ThsB protein recognizes phage infection and produces a signaling molecule cyclic ADP ribose isomer 1''-3'gcADPR [5]. 1''-3' gcADPR is then bound by the ThsA SLOG domain and activates NAD+ hydrolysis by the SIR2 domain resulting in NAD+ depletion and host cell death [4]. However, it was not clear how binding of the sigaling molecule turns on NADase activity of ThsA. In this work we reconstituted Thoeris enzymatic activities in vitro and using structural and biochemical methods showed the ThsA activation mechanism.
[1] Tesson, F., Hervé, A., Mordret, E., Touchon, M., d'Humières, C., Cury, J., & Bernheim, A. (2022). Systematic and quantitative view of the antiviral arsenal of prokaryotes. Nature Communications 2022 13:1, 13(1), 1–10.
[2] Doron, S., Melamed, S., Ofir, G., Leavitt, A., Lopatina, A., Keren, M., Amitai, G., & Sorek, R. (2018). Systematic discovery of antiphage defense systems in the microbial pangenome. Science, 359(6379),
[3] Ka, D., Oh, H., Park, E., Kim, J. H., & Bae, E. (2020). Structural and functional evidence of bacterial antiphage protection by Thoeris defense system via NAD+ degradation. Nature Communications, 11(1), 1-8.
[4] Ofir, G., Herbst, E., Baroz, M., Cohen, D., Millman, A., Doron, S., Tal, N., Malheiro, D. B. A., Malitsky, S., Amitai, G., & Sorek, R. (2021). Antiviral activity of bacterial TIR domains via immune signalling molecules. Nature, 600(7887), 116-120.
[5] Leavitt, A., Yirmiya, E., Amitai, G., Lu, A., Garb, J., Herbst, E., Morehouse, B. R., Hobbs, S. J., Antine, S. P., Sun, Z. Y. J., Kranzusch, P. J., & Sorek, R. (2022). Viruses inhibit TIR gcADPR signalling to overcome bacterial defence. Nature 2022 611:7935, 611(7935), 326–331.
