Thoeris is a bacterial antiphage defense system, which consists of two genes, thsA and thsB, via NAD+ degradation [1-3]. ThsA has robust NAD+ cleavage activity and and a two-domain architecture containing a N-terminal NAD-binding domain (denoted as sirtuin-like or Macro) and C-terminal SLOG-like domain. In some instances, such as in B. amyloliquefaciens ThsA has an N-terminal transmembrane domain [1]. ThsB (also referred to as TIR1 and TIR2) is structurally similar to TIR domain proteins but without enzymatic activity. This is the TIR-like domain of ThsB proteins, which adopts a Rossmann-like fold. ThsB is responsible for recognizing phage infection [2].

1: Systematic discovery of antiphage defense systems in the microbial pangenome. Doron S, Melamed S, Ofir G, Leavitt A, Lopatina A, Keren M, Amitai G, Sorek R; Science. 2018; [Epub ahead of print] PMID:29371424

2: Antiviral activity of bacterial TIR domains via immune signalling molecules. Ofir G, Herbst E, Baroz M, Cohen D, Millman A, Doron S, Tal N, Malheiro DBA, Malitsky S, Amitai G, Sorek R; Nature. 2021;600:116-120. PMID:34853457

3: Structural and functional evidence of bacterial antiphage protection by Thoeris defense system via NAD(+) degradation. Ka D, Oh H, Park E, Kim JH, Bae E; Nat Commun. 2020;11:2816. PMID:32499527