1.E.24 The Bacterophase Dp-1 Holin (Dp-1 Holin) Family

The genes coding for the lytic system of the pneumococcal phage, Dp-1, has been cloned and characterized (Sheehan et al., 1997). The lytic enzyme of this phage (Pal), an N-acetyl-muramoyl-L-alanine amidase, shows a modular organization similar to that described for the lytic enzymes of Streptococcus pneumoniae and its bacteriophages. The construction of chimeric enzymes between pneumococcus and bacteria (or phages) that belong to different Gram-positive families has shown that the interchange of functional domains switches enzyme specificity.

The holin of phage Dp-1 is 74 aas long with two probable TMSs (residues 12-32 and 39-57). It shows sequence similarity (30% identity) with a holin encoded within the genone of Enterococcus faecalis (Paulsen et al., 2003). Several Gram-positive bacteria and their phage also possess this family of holins, representatives of which are listed in the table.



Escobedo, S., A.B. Campelo, U. Wegmann, P. García, A. Rodríguez, and B. Martínez. (2019). Insight into the Lytic Functions of the Lactococcal Prophage TP712. Viruses 11:.

Labrie, S., N. Vukov, M.J. Loessner, and S. Moineau. (2004). Distribution and composition of the lysis cassette of Lactococcus lactis phages and functional analysis of bacteriophage ul36 holin. FEMS Microbiol. Lett. 233: 37-43.

Paulsen, I.T., L. Banerjei, G.S.A. Myers, K.E. Nelson, R. Seshadri, T.D. Read, D.E. Fouts, J.A. Eisen, S.R. Gill, J.F. Heidelberg, H. Tettelin, R.J. Dodson, L. Umayam, L. Brinkac, M. Beanan, S. Daugherty, R.T. DeBoy, S. Durkin, J. Kolonay, R. Madupu, W. Nelson, J. Vamathevan, B. Tran, J. Upton, T. Hansen, J. Shetty, H. Khouri, T. Utterback, D. Radune, K.A. Ketchum, B.A. Dougherty, and C.M. Fraser. (2003). Role of Mobile DNA in the Evolution of Vancomycin-Resistant Enterococcus faecalis. Science. 299: 2071-2074.

Roces, C., A.B. Campelo, S. Escobedo, U. Wegmann, P. García, A. Rodríguez, and B. Martínez. (2016). Reduced Binding of the Endolysin LysTP712 to Lactococcus lactis ΔftsH Contributes to Phage Resistance. Front Microbiol 7: 138.

Sheehan, M.M., García, J.L., López R., and García P. (1997). The lytic enzyme of the pneumococcal phage Dp-1: a chimeric lysin of intergeneric origin. Mol Microbiol. 25: 717-725.


TC#NameOrganismal TypeExample
1.E.24.1.1The phage Dp-1 holin (74 aas) (Sheehan et al., 1997)PhageHolin of Dp-1 Bacteriophage (O03978)
1.E.24.1.2The enterococcal chromosomal holin (68 aas)FirmicutesHolin of Enterococcus faecalis (Q830I1)

Phage PhiAM2 holin (74 aas) (Identical to Lactococcus phage ul36 gpOfr74B holin (Labrie et al. 2004)).


Holin of PhiAM2 Bacteriophage (Q9G090)


Holin of 74 aas and 2 TMSs (Roces et al. 2016). It is identical to the holin of Lactococcal Prophage TP712 (Escobedo et al. 2019).


Holin of Lactococcus lactis subsp. cremoris (A2RJJ3); identical to the holin of

1.E.24.1.5Putative chromosomal holin (87 aas)ActinobacteriaHolin of Bifidobacterium adolescentis (A7A6X9)

TC#NameOrganismal TypeExample

Holin family protein


Holin family protein of Solobacterium moorei


TC#NameOrganismal TypeExample

Uncharacterized protein


Uncharacterized protein of Collinsella tanakaei