This protein family includes Immunity protein Tgi2PP from Pseudomonas fluorescens (PFL_3036), the immunity component of a effector immunity pair secreted by the type VI secretion system (T6SS) of this bacteria. Its structure consists of a short N-terminal 3-10 helix and a central five-stranded beta-sheet flanked by three alpha- helices [1].

1: Identification, structure, and function of a novel type VI secretion peptidoglycan glycoside hydrolase effector-immunity pair. Whitney JC, Chou S, Russell AB, Biboy J, Gardiner TE, Ferrin MA, Brittnacher M, Vollmer W, Mougous JD; J Biol Chem. 2013;288:26616-26624. PMID:23878199