This domain is found in Tlde1 family of antibacterial effectors secreted by the type VI secretion system (T6SS). Tlde1 family is evolutionarily related to l,d transpeptidases which form mDAP3-mDAP3 peptidoglycan crosslinks. Tlde1 family is widespread among Proteobacteria and is divided into three subfamilies (Tlde1a, Tlde1b and Tlde1c) [1].

1: A Family of T6SS Antibacterial Effectors Related to l,d-Transpeptidases Targets the Peptidoglycan. Sibinelli-Sousa S, Hespanhol JT, Nicastro GG, Matsuyama BY, Mesnage S, Patel A, de Souza RF, Guzzo CR, Bayer-Santos E; Cell Rep. 2020;31:107813. PMID:32579939