Phage_holin_V_2 is a family of small hydrophobic proteins with three transmembrane domains of the Hol44 family. These proteins are produced by double-stranded DNA bacteriophages that use an endolysin-holin strategy to achieve lysis of their hosts. The endolysins are peptidoglycan-degrading enzymes that are usually accumulated in the cytosol until access to the cell wall substrate is provided by the holin membrane lesion. Full activity of the endolysin Lys44 from oenophage fOg44 requires sudden ion-nonspecific dissipation of the proton motive force, undertaken by the fOg44 holin during phage-infection [1,2,3].

1: Functional and structural features of the holin HOL protein of the Lactobacillus plantarum phage phi gle: analysis in Escherichia coli system. Oki M, Kakikawa M, Nakamura S, Yamamura ET, Watanabe K, Sasamoto M, Taketo A, Kodaira K; Gene. 1997;197:137-145. PMID:9332359

2: The complete genome sequence of Clostridium difficile phage phiC2 and comparisons to phiCD119 and inducible prophages of CD630. Goh S, Ong PF, Song KP, Riley TV, Chang BJ; Microbiology. 2007;153:676-685. PMID:17322187

3: Nisin-triggered activity of Lys44, the secreted endolysin from Oenococcus oeni phage fOg44. Nascimento JG, Guerreiro-Pereira MC, Costa SF, Sao-Jose C, Santos MA; J Bacteriol. 2008;190:457-461. PMID:17981964