TCDB is operated by the Saier Lab Bioinformatics Group


1.E.19 The Clostridium difficile TcdE Holin (TcdE Holin) Family

Toxigenic strains of C. difficile produce two large toxins (TcdA and TcdB) encoded within a pathogenicity locus. tcdE, encoded between tcdA and tcdB, encodes a 166 aa protein which causes death to E. coli when expressed, and the structure of TcdE resembles holins. TcdE acts on the bacterial membrane. Since TcdA and TcdB lack signal peptides, they may be released via TcdE either prior to or subsequent to cell lysis. Other Clostridial species bear homologues of TcdE.  This family belongs to the Phage holin 4 superfamily. 

The transport reaction believed to be catalyzed by TcdE is:


Toxin (in) Toxin (out)



This family belongs to the: Holin Superfamily IV.

References associated with 1.E.19 family:

Govind, R. and B. Dupuy. (2012). Secretion of Clostridium difficile toxins A and B requires the holin-like protein TcdE. PLoS Pathog 8: e1002727. 22685398
Govind, R., L. Fitzwater, and R. Nichols. (2015). Observations on the Role of TcdE Isoforms in Clostridium difficile Toxin Secretion. J. Bacteriol. 197: 2600-2609. 26013487
Jin, M., T. Ye, and X. Zhang. (2013). Roles of bacteriophage GVE2 endolysin in host lysis at high temperatures. Microbiology 159: 1597-1605. 23782802
Kong M. and Ryu S. (2015). Bacteriophage PBC1 and its endolysin as an antimicrobial agent against Bacillus cereus. Appl Environ Microbiol. 81(7):2274-83. 25595773
Sirigi Reddy, A.R., B.P. Girinathan, R. Zapotocny, and R. Govind. (2013). Identification and characterization of Clostridium sordellii toxin gene regulator. J. Bacteriol. 195: 4246-4254. 23873908
Takác, M., A. Witte, and U. Bläsi. (2005). Functional analysis of the lysis genes of Staphylococcus aureus phage P68 in Escherichia coli. Microbiology 151: 2331-2342. 16000723
Tan, K.S., B.Y. Wee, and K.P. Song. (2001). Evidence for holin function of tcdE gene in the pathogenicity of Clostridium difficile. J. Med. Microbiol. 50: 613-619. 11444771
Zimmer, M., N. Vukov, S. Scherer, and M.J. Loessner. (2002). The murein hydrolase of the bacteriophage phi3626 dual lysis system is active against all tested Clostridium perfringens strains. Appl. Environ. Microbiol. 68: 5311-5317. 12406719