This domain is found at the C-terminal region of the type VI secretion system (T6SS) immunity protein Tdi1 from Agrobacterium tumefaciens (Atu4351, Swiss:Q7CUQ2) and similar bacterial proteins Tdi1 is organised into a N-terminal GAD-related domain (Pfam:PF08887) and a C-terminal domain likely to exist as an insertion in the GAD-like domain. This domain shows a two-stranded antiparallel beta-sheet and four helices. A positive groove that extends to both domains may be associated with nucleotide binding [1].

1: Crystal structure of the type VI immunity protein Tdi1 (Atu4351) from Agrobacterium tumefaciens. Shi L, Gao Z, Zhang T, Zhang H, Dong Y; Acta Crystallogr F Struct Biol Commun. 2019;75:153-158. PMID:30839288