1.E.31 The SPP1 Holin (SPP1 Holin) Family The SPP1 Holin Family consists of proteins of 90 - 160 aas with two TMSs
References:
Aunpad, R. and W. Panbangred. (2012). Evidence for two putative holin-like peptides encoding genes of Bacillus pumilus strain WAPB4. Curr. Microbiol. 64: 343-348.
Babar, T.K., T.R. Glare, J.G. Hampton, M.R.H. Hurst, and J.O. Narciso. (2022). Isolation, Purification, and Characterisation of a Phage Tail-Like Bacteriocin from the Insect Pathogenic Bacterium. Biomolecules 12:.
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.
Durmaz, E. and T.R. Klaenhammer. (2007). Abortive phage resistance mechanism AbiZ speeds the lysis clock to cause premature lysis of phage-infected Lactococcus lactis. J. Bacteriol. 189: 1417-1425.
Fernandes, S. and C. São-José. (2017). Probing the function of the two holin-like proteins of bacteriophage SPP1. Virology 500: 184-189.
Jin, M., T. Ye, and X. Zhang. (2013). Roles of bacteriophage GVE2 endolysin in host lysis at high temperatures. Microbiology 159: 1597-1605.
Krogh, S., S.T. Jørgensen, and K.M. Devine. (1998). Lysis genes of the Bacillus subtilis defective prophage PBSX. J. Bacteriol. 180: 2110-2117.
Kyogoku, K. and J. Sekiguchi. (1996). Cloning and sequencing of a new holin-encoding gene of Bacillus licheniformis. Gene 168: 61-65.
Leprince, A., M. Nuytten, E. July, C. Tesseur, and J. Mahillon. (2022). Getting Outside the Cell: Versatile Holin Strategies Used by Distinct Phages to Leave Their Bacillus thuringiensis Host. J. Virol. e0069622. [Epub: Ahead of Print]
Examples:
TC#	Name	Organismal Type	Example
1.E.31.1.1	Lactococcus lactis phage Phi31 holin of the Holin SPP1 or Phage_holin family (Durmaz and Klaenhammer 2007).	Firmicute phage	Holin of phage Phi31

1.E.31.1.10	Putative holin	Firmicute phage	*Putative holin of Brochithrix* phage A9**

1.E.31.1.11	XhlB holin of 109 aas; belongs to the SPP1 family.	Firmicutes	XhlB of Staphylococcus epidermidis

1.E.31.1.12	XhlB holin of 87 aas and 2 TMSs (Aunpad and Panbangred 2012).	Firmicutes	XhlB holin of Bacillus pumilus

1.E.31.1.13	Two component holin, requiring two non-homologous small proteins, the gene 26 product (O48472; 82 aas, 2 TMSs, a member of family TC# 1.E.31) and the gene 24.1 product (O48470; 83 aas; 1 C-terminal TMS, not homologous to members of family 1.E.31) (Fernandes and São-José 2017).		Holin of Bacillus phage SPP1 Orf26 Orf24.1

1.E.31.1.14	Two component holin, requiring two non-homologous small proteins, one of 87 aas and 2 TMSs (E0U1U5), a member of family TC# 1.E.31, and another gene product, XhlA, of 89 aas with 1 C-terminal TMS (P39798), not homologous to members of family 1.E.31 (Fernandes and São-José 2017).		Holin of Bacillus phage PBSX Orf of 87 aas and 2 TMSs (E0U1U5) Orf of 89 aas and 1 C-terminal TMS (P39798)

1.E.31.1.15	*Holin-like protein of 81 aas and 2 TMSs. The holin and autolyin interact directly (Jin et al.* 2013).**		*Holin of Geobacillus* virus E3**

1.E.31.1.16	Holin V of 99 aas and 2 TMSs. Its function as a holin protein was confirmed as its expression in E. coli impaired cell growth and viability while holV expression in B. thuringiensis led to bacterial lysis, which was enhanced by coexpressing the holin with its cognate endolysin (Leprince et al. 2022).		HolV of Bacillus phage Vp4

1.E.31.1.2	Prophage L54a holin of the SPP1 family	Firmicute prophage	Holin of Staphylococcus aureus

1.E.31.1.3	Holin of 74 aas and 2 TMSs	Firmicutes	Holin of Bacillus pumilus

1.E.31.1.4	Holin	Firmicutes	Holin of Streptococcus gallolyticus

1.E.31.1.5	Holin	Actinobacteria	Holin of Bifidobacterium calenulatum

1.E.31.1.6	*Holin XhlB of 87 aas and 2 TMSs (Krogh et al.* 1998; Babar et al. 2022).**	Firmicutes	Holin XhlB of Bacillus subtilis prophage PBSX

1.E.31.1.7	Holin XpaG2 (Kyogoku and Sekiguchi 1996).	Firmicutes	X[aG2 pf Bacillus licheniformis

1.E.31.1.8	Holin-like protein	Actinobacteria	Holin-like protein of Bifidobacterium longum

1.E.31.1.9	Putative holin	Firmicute phage	*Putative holin of Bacillus* phage BPS13**

Examples:
TC#	Name	Organismal Type	Example
1.E.31.2.1	Putative holin of 77 aas and 2 TMSs	Bacilli (Firmicutes)	Putative holin of Bacillus thuringiensis

1.E.31.2.2	Putative holin of 77 aas and 2 TMS	Bacilli (Firmicutes)	Putative holin of Bacillus cereus

1.E.31.2.3	Holin	Firmicutes	Holin of Bacillus cereus

1.E.31.2.4	Putative holin	Actinobacteria	Putative holin of Brevibacterium laterosporus

Examples:
TC#	Name	Organismal Type	Example
1.E.31.3.1	Putative holin (Orf041) of Staphylococcal phage 2683	Firmicute phage	Holin of Staphylococcus aureus phage 2683

1.E.31.3.2	Putative firmicute holin	Firmicutes	Putative holin of Solibacillus silvestris