M2 hol family

The Mycobacterial 2 TMS Phage Holin Family is a group of transporters belonging to the Holin Superfamily VII. The Mycobactrerial 2 transmembrane segment Holins have been identified and recognized by Catalao et al. The Mycobacterium phage D29 gp11 protein is a holin that, upon expression, rapidly kills both E. coli and Mycobacterium smegmatis. Shortening gp11 from its C-terminus resulted in diminished cytotoxicity and smaller holes. The two TMSs at the N-terminus alone do not integrate into the cytoplasmic membrane and do not show toxicity. Fusion of the two TMSs and a small C-terminal coiled-coil region resulted in restoration of cell killing. The second TMS is dispensable for toxicity. The gp11 C-terminal region is therefore necessary but not sufficient for toxicity.