The ''Mycobacterial'' 2 TMS Phage Holin (M2 Hol) Family
TC# 1.E.36 is a group of transporters belonging to the
Holin Superfamily VII The Holin superfamily VII is a superfamily of integral membrane transport proteins. It is one of the seven different holin superfamilies in total. In general, these proteins are thought to play a role in regulated cell death, although functionalit ...
. The
''Mycobactrerial'' 2 transmembrane segment (TMS) Holins have been identified and recognized by Catalao et al (2012). The ''Mycobacterium'' phage D29 gp11 protein
TC# 1.E.36.1.7 is a holin that, upon expression, rapidly kills both ''
E. coli
''Escherichia coli'' (),Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. also known as ''E. coli'' (), is a Gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus ''Escher ...
'' and ''
Mycobacterium smegmatis''. Shortening gp11 from its
C-terminus
The C-terminus (also known as the carboxyl-terminus, carboxy-terminus, C-terminal tail, C-terminal end, or COOH-terminus) is the end of an amino acid chain (protein or polypeptide), terminated by a free carboxyl group (-COOH). When the protein is ...
resulted in diminished
cytotoxicity
Cytotoxicity is the quality of being toxic to cells. Examples of toxic agents are an immune cell or some types of venom, e.g. from the puff adder (''Bitis arietans'') or brown recluse spider (''Loxosceles reclusa'').
Cell physiology
Treating cells ...
and smaller holes. The two TMSs at the
N-terminus
The N-terminus (also known as the amino-terminus, NH2-terminus, N-terminal end or amine-terminus) is the start of a protein or polypeptide, referring to the free amine group (-NH2) located at the end of a polypeptide. Within a peptide, the ami ...
alone do not integrate into the cytoplasmic membrane and do not show toxicity.
Fusion of the two TMSs and a small C-terminal
coiled-coil
A coiled coil is a structural motif in proteins in which 2–7
alpha helix, alpha-helices are coiled together like the strands of a rope. (Protein dimer, Dimers and Protein trimer, trimers are the most common types.) Many coiled coil-type protei ...
region resulted in restoration of cell killing. The second TMS is dispensable for toxicity. The gp11 C-terminal region is therefore necessary but not sufficient for toxicity.
See also
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Holin
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Lysin
Lysins, also known as endolysins or murein hydrolases, are hydrolytic enzymes produced by bacteriophages in order to cleave the host's cell wall during the final stage of the lytic cycle. Lysins are highly evolved enzymes that are able to target ...
*
Transporter Classification Database
Further reading
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References
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Holins
Protein families