1.E.11 The φ11 Holin (φ11 Holin) Family See 1.E for a generalized description of Holins. The pneumococcal EJ-1 phage holin (EJh) is a hydrophobic peptide (85 aas) with 2 putative TMSs displaying lethal inner membrane disruptive activity. The synthetic N-terminal TMS flanked by its N-terminal positively charged residues folds into a transmembrane α-helix that increases the membrane permeability. Oligomeric channels of various sizes form depending on the peptide to lipid ratio (Haro et al., 2003). By atomic force microscopy, peptide-induced membrane holes can be seen.
This family belongs to the Holin I Superfamily.
References:
Bon, J., N. Mani, and R.K. Jayaswal. (1997). Molecular analysis of lytic genes of bacteriophage 80 alpha of Staphylococcus aureus. Can. J. Microbiol. 43: 612-616.
Cerca, N., R. Oliveira, and J. Azeredo. (2007). Susceptibility of Staphylococcus epidermidis planktonic cells and biofilms to the lytic action of staphylococcus bacteriophage K. Lett Appl Microbiol 45: 313-317.
Curtin, J.J. and R.M. Donlan. (2006). Using bacteriophages to reduce formation of catheter-associated biofilms by Staphylococcus epidermidis. Antimicrob. Agents Chemother. 50: 1268-1275.
Diaz, E., M. Munthali, H. Lunsdorf, J.V. Holtje, and K.N. Timmis. (1996). The two-step lysis system of pneumococcal bacteriophage EJ-1 is functional in gram-negative bacteria: triggering of the major pneumococcal autolysin in Escherichia coli. Mol. Microbiol. 19: 667-681.
Haro, A., M. Vélez, E. Goormaghtigh, S. Lago, J. Vázquez, D. Andreu, and M. Gasset. (2003). Reconstitution of holin activity with a synthetic peptide containing the 1-32 sequence region of EJh, the EJ-1 phage holin. J. Biol. Chem. 278: 3929-3936.
Loessner, M.J., S. Gaeng, G. Wendlinger, S.K. Maier, and S. Scherer. (1998). The two-component lysis system of Staphylococcus aureus bacteriophage Twort: a large TTG-start holin and an associated amidase endolysin. FEMS Microbiol. Lett. 162: 265-274.
Martínez, V., P. García, J.L. García, and M.A. Prieto. (2011). Controlled autolysis facilitates the polyhydroxyalkanoate recovery in Pseudomonas putida KT2440. Microb Biotechnol 4: 533-547.
Riangrungroj, P., W. Visessanguan, and U. Leartsakulpanich. (2023). Production of Lactobacillus plantarum ghosts by conditional expression of a prophage-encoded holin. FEMS Microbiol. Lett. 370:.
Seal, B.S., D.E. Fouts, M. Simmons, J.K. Garrish, R.L. Kuntz, R. Woolsey, K.M. Schegg, A.M. Kropinski, H.W. Ackermann, and G.R. Siragusa. (2011). Clostridium perfringens bacteriophages ΦCP39O and ΦCP26F: genomic organization and proteomic analysis of the virions. Arch Virol 156: 25-35.
Song, J., F. Xia, H. Jiang, X. Li, L. Hu, P. Gong, L. Lei, X. Feng, C. Sun, J. Gu, and W. Han. (2016). Identification and characterization of HolGH15: the holin of Staphylococcus aureus bacteriophage GH15. J Gen Virol 97: 1272-1281.
Examples:
TC#	Name	Organismal Type	Example
1.E.11.1.1	*Holin 145 (Bon et al.* 1997)**	Staphylococcus phage φ11	Holin (145 aas)

1.E.11.1.10	Holin of 100 aas and 2 TMSs	Actinobacteria	Holin of Atopobium parvulum

1.E.11.1.11	*Holin of 120 aas and 2 N-terminal TMSs. This holin has been used to generate pores in "ghosts" of this bacterium (Riangrungroj et al.* 2023).**		*Holin of Lactiplantibacillus plantarum* subsp. plantarum**

1.E.11.1.12	Holin of 82 aas and 2 TMSs.		Holin of Firmicutes bacterium HGW-Firmicutes-17

1.E.11.1.2	Holin	Lactococcus phage Tuc 2009	Holin (88 aas)

1.E.11.1.3	Holin of 85 aas, Ejh (Diaz et al. 1996). A synthetic peptide based on Ejh has been reconstituted and shown to be active (Haro et al. 2003). Ejh has been used to promote release of polyhydroxyalkanoate granules from bacterial cells (Martínez et al. 2011).	*EJh of Streptococcus pneumoniae* phage EJ-1**	Holin EJh (85 aas)

1.E.11.1.4	Holin	Firmicutes	Holin of of Streptococcus pyongenes

1.E.11.1.5	*Holin HolTW (Loessner et al.* 1998).**	Firmicute viruses	*Holin HolTS of Staphylococcus* phage TWORT**

1.E.11.1.6	Putative holin	Firmicutes	Putative holin of Listeria innocua

1.E.11.1.7	Putative holin; phage phiLC3 holin family	Firmicutes	Putative holin of Streptococcus sanguinis

1.E.11.1.8	Holin (Orf33) of 167 aas from Stahylococcus phage K. Phage K lysis differentially affects planctonic and biofilm cells (Cerca et al. 2007; Curtin and Donlan 2006). 95% identical to HolGH15 of phage GH15 of S. aureus which has broad host range antibacterial activity against many pathogens (Song et al. 2016).	Firmicute viruses	*Orf33 of Stahylococcus* phage K; HolGH15 of Staphylococcus phage GH15**

1.E.11.1.9	Holin of the phage phi LC3 family of 91 aas and 2 TMSs	Actinobacteeria	Holin of Collinsella aerofaciens

Examples:
TC#	Name	Organismal Type	Example
1.E.11.2.1	*Holin of Clostridium* phage phiCP390 (Seal et al. 2011). This holin is identical to the holin of phage phiCP26F (gp23; F2VHY0).**	Viruses	*Holin of Clostridium perfringens* phage PhiCP390**

1.E.11.2.2	Putative holin	Firmicutes	Putative holin of Clostridium perfringens

1.E.11.2.3	Putative holin	Firmicutes	Putative holin of Geobacillus kustophilus

1.E.11.2.4	Uncharacterized holin phage phi LC3 of 63 aas and 2 TMSs.		Putative holin of Ruminiclostridium papyrosolvens

1.E.11.2.5	Holin of 83 aas and 2 TMSs, Phage_holin_1.		Holin of a eubacterium

Examples:
TC#	Name	Organismal Type	Example
1.E.11.3.1	Putative holin of 49 aas and 1 TMS. TMS 1 corresponds to TMS 2 in the holins of TC subfamilies 1.E.11.1 and 1.E.11.2.	Proteobacteria	Putative holin of Pseudomonas putida

1.E.11.3.10	Uncharacterized protein of 60 aas and 1 TMS		UP of Chromatiales bacterium 21-64-14 (mine drainage metagenome)

1.E.11.3.11	Uncharacterized protein of 62 aas and 1 TMS		UP of Chromatium okenii

1.E.11.3.2	Putative holin of 50 aas and 1 TMS	Proteobacteria	Putative holin of Pseudomonas syringae

1.E.11.3.3	Putative uncharacterized holin of 32 aas and 1 TMS.		*UP of Halomonas* sp. HL-48 (microbial mat metagenome)**

1.E.11.3.4	Uncharacterized protein of 48 aas and 1 TMS.		*UP of Marinobacter* sp. T13-3 (gas well metagenome)**

1.E.11.3.5	Uncharacterized protein of 63 aas and 1 TMS (N-terminal)		UP of Mangrovitalea sediminis

1.E.11.3.6	Uncharacterized protein of 41 aas and 1 TMS		UP of Nitrincola nitratireducens

1.E.11.3.7	Uncharacterized protein of 48 aas and 1 TMS.		UP of Halioglobus sediminis

1.E.11.3.8	Uncharacterized protein of 49 aas and 1 TMS		UP of Alcanivorax nanhaiticus

1.E.11.3.9	Uncharacterized protein of 54 aas and 1 TMS		UP of Gynuella sunshinyii

Examples:
TC#	Name	Organismal Type	Example
1.E.11.4.1	Holin of 176 aas and 2 N-terminal TMSs.		Holin of Lactiplantibacillus plantarum