The ''Clostridioides difficile'' TcdE Holin (TcdE Holin) Family
TC# 1.E.19
is a group of transporters belonging to the

Holin Superfamily IV The Holin superfamily IV is a superfamily of integral membrane transport proteins. It is one of the seven different holin superfamilies in total. The Holin superfamily IV includes the TC families: 1.E.10- The ''Bacillus subtilis'' φ29 Holin (φ2 ...

. A representative list of its members can be found in th
Transporter Classification Database
Toxigenic strains of ''

C. difficile ''Clostridioides difficile'' ( syn. ''Clostridium difficile'') is a bacterium known for causing serious diarrheal infections, and may also cause colon cancer. It is known also as ''C. difficile'', or ''C. diff'' (), and is a Gram-positive spec ...

'' produce two large toxins (TcdA and TcdB) encoded within a pathogenicity locus. ''tcdE,'' encoded between ''tcdA'' and ''tcdB,'' encodes a 166 amino acyl (aa) protein which causes

death Death is the end of life; the irreversible cessation of all biological functions that sustain a living organism. Death eventually and inevitably occurs in all organisms. The remains of a former organism normally begin to decompose sh ...

to ''

E. coli ''Escherichia coli'' ( )Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. is a gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus ''Escherichia'' that is commonly foun ...

'' when expressed, and the structure of TcdE resembles

holin Holins are a diverse group of small proteins produced by dsDNA bacteriophages in order to trigger and control the degradation of the host's cell wall at the end of the lytic cycle. Holins form pores in the host's cell membrane, allowing lysins t ...

s. 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 Lysis ( ; from Greek 'loosening') is the breaking down of the membrane of a cell, often by viral, enzymic, or osmotic (that is, "lytic" ) mechanisms that compromise its integrity. A fluid containing the contents of lysed cells is called a ' ...

. Other

Clostridia The Clostridia are a highly polyphyletic class of Bacillota, including '' Clostridium'' and other similar genera. They are distinguished from the Bacilli by lacking aerobic respiration. They are obligate anaerobes and oxygen is toxic to them ...

l species bear homologues of TcdE. The transport reaction believed to be catalyzed by TcdE is:

Toxin (in) → Toxin (out)

References

Holins Protein families {{Membrane-protein-stub

See also

Further reading

References