TCDB is operated by the Saier Lab Bioinformatics Group
TCIDNameDomainKingdom/PhylumProtein(s)
1.E.1.1.1









Lysis protein S; also called ''pinholin'' or pinholin S(21)68, of 71 aas and 2 TMSs. It forms small heptameric pores that depolarize the membrane (Park et al., 2007; Pang et al., 2009).  This holin is of topological Class II, forming 2 TMSs, with the N- and C-termini inside (Park et al. 2006). TMS1 partially externalizes from the lipid bilayer regulates channel-formation and interacts with the membrane surface, whereas TMS2 remains buried in the lipid bilayer in the active conformation and forms the pore (Ahammad et al. 2019). Pinholin S(21)68 triggers the lytic cycle of bacteriophage phi21 in infected Escherichia coli. Activated transmembrane dimers oligomerize into small holes and uncouple the proton gradient. Structural models have been proposed for (1) the oligomeric pinhole (right-handed heptameric TMD2 bundle), (2) the active dimer (right-handed Gly-zipped TMD2/TMD2 dimer), and (3) the full-length pinholin protein before being triggered (Gly-zipped TMD2/TMD1-TMD1/TMD2 dimer in a line) (Steger et al. 2020).

Viruses
Caudovirales
Lysis protein S (71 aas; P27360)
1.E.1.1.2









Lysis protein S.  Identical to EssD, a holin from lambdoid prophage DLP12 with two TMSs (Srividhya and Krishnaswamy 2007).

Bacteria
Proteobacteria
Lysis protein S (71aas; P77237)
1.E.1.1.3









Holin of 68 aas and 1 TMS.  Deleting the lysis module, encoding the holin, lysin and two spanins, increases outer membrane vesicle (OMV) production, suggesting that during evolution this operon has been domesticated to regulate vesiculation, possibly through the elimination of non-recyclable peptidoglycan fragments (Pasqua et al. 2021). The expression of the lysis module is negatively regulated by environmental stress stimuli as high osmolarity, low pH and low temperature (Pasqua et al. 2021).

Viruses
Caudovirales
Holin of E. coli phage H-19B (68 aas; AAD04658)
1.E.1.1.4









Lysis S family holin protein

Bacteria
Proteobacteria
Lysis S holin of E. coli
1.E.1.1.5









Hypothetical protein, HP

Bacteria
Proteobacteria
HP of Cronobacter sakazakii
1.E.1.1.6









Holin of 62 aas and 1 TMS

Bacteria
Proteobacteria
Putative holin of Hamiltonella defensa
1.E.1.1.7









Lysis S family protein with fused N-terminal holin domain of 2 - 3 TMSs; 720 aas

Bacteria
Proteobacteria
Holin-Lysis S fusion protein of E. coli
1.E.1.1.8









Holin of 86 aas and 1 TMS.

Bacteria
Proteobacteria
Holin of Pectobacterium polonicum
1.E.1.1.9









Putative uncharacterized holin of 75 aas and 1 or 2 TMSs.  Shows extensive similarity to members of TC family 1.E.25.

Bacteria
Proteobacteria
Holin of Salmonella enterica