The Phage_holin_BhlA family is a family of holin-like proteins from both bacteriophages and bacterial chromosomes. In bacteriophage, holins are small membrane proteins that accumulate and oligomerise to form non-specific lesions in the cytoplasmic membrane allowing the release of the second protein, endolysins, to access the peptidoglycan [1]. Most holins share common structural features: two or three transmembrane domains separated by a beta-turn, a short hydrophilic N-terminus, a highly charged C-terminus and a dual translational start motif. The BhlA holin of Bacillus is found to be toxic to the host cell where the site of action of is on the cell membrane and causes bacterial death by cell membrane disruption [2].

1: Functional analysis of a putative holin-like peptide-coding gene in the genome of Bacillus licheniformis AnBa9. Anthony T, Chellappa GS, Rajesh T, Gunasekaran P; Arch Microbiol. 2010;192:51-56. PMID:19967339

2: Evidence for two putative holin-like peptides encoding genes of Bacillus pumilus strain WAPB4. Aunpad R, Panbangred W; Curr Microbiol. 2012;64:343-348. PMID:22231453