Editing Bacteriocin (section)

===From Gram negative bacteria===

Gram negative bacteriocins are typically classified by size. Microcins are less than 20 kDa in size, colicin-like bacteriocins are 20 to 90 kDa in size and tailocins or so called high molecular weight bacteriocins which are multi subunit bacteriocins that resemble the tails of bacteriophages. This size classification also coincides with genetic, structural and functional similarities.

====Microcins====
See main article on [[microcin]]s.

====Colicin-like bacteriocins====
[[Colicins]] are bacteriocins found in the Gram-negative ''E. coli''. Similar bacteriocins (CLBs, colicin-like bacteriocins) occur in other Gram-negative bacteria. CLBs typically target same species and have species-specific names: klebicins from ''Klebsiella'' and pesticins from ''Yersinia pestis''.<ref>{{cite journal | vauthors = Behrens HM, Six A, Walker D, Kleanthous C | title = The therapeutic potential of bacteriocins as protein antibiotics | journal = Emerging Topics in Life Sciences | volume = 1 | issue = 1 | pages = 65–74 | date = April 2017 | pmid = 33525816 | pmc = 7243282 | doi = 10.1042/ETLS20160016 | veditors = Walker D }}</ref> ''Pseudomonas'' -genus produces bacteriocins called [[pyocin]]s. S-type pyocins belong to CLBs, but R- and F-type pyocins belong to tailocins.<ref>{{cite journal | vauthors = Michel-Briand Y, Baysse C | title = The pyocins of Pseudomonas aeruginosa | journal = Biochimie | volume = 84 | issue = 5–6 | pages = 499–510 | date = May 2002 | pmid = 12423794 | doi = 10.1016/S0300-9084(02)01422-0 }}</ref>

CLBs are distinct from Gram-positive bacteriocins. They are modular proteins between 20 and 90 kDa in size. They often consist of a receptor binding domain, a translocation domain and a cytotoxic domain. Combinations of these domains between different CLBs occur frequently in nature and can be created in the laboratory. Due to these combinations further subclassification can be based on either import mechanism (group A and B) or on cytotoxic mechanism (nucleases, pore forming, M-type, L-type).<ref name="Colicin biology" />

====Tailocins====
Most well studied are the tailocins of ''[[Pseudomonas aeruginosa]]''. They can be further subdivided into R-type and F-type pyocins.<ref>{{cite journal | vauthors = Ghequire MG, De Mot R | title = Ribosomally encoded antibacterial proteins and peptides from Pseudomonas | journal = FEMS Microbiology Reviews | volume = 38 | issue = 4 | pages = 523–68 | date = July 2014 | pmid = 24923764 | doi = 10.1111/1574-6976.12079 | doi-access = free }}</ref>
Some research was made to identify the pyocins and show how they are involved in the “cell-to-cell” competition of the closely related Pseudomonas bacteria.

The two types of tailocins differ by their structure; they are both composed of a sheath and a hollow tube forming a long helicoidal hexameric structure attached to a baseplate. There are multiple tail fibers that allow the viral particle to bind to the target cell. However, the R-pyocins are a large, rigid contractile tail-like structure whereas the F-pyocins are a small flexible, non-contractile tail-like structure.

The tailocins are coded by prophage sequences in the bacteria genome, and the production will happen when kin bacteria are spotted in the environment of the producer. 
The particles are synthesized in the center of the cells and after maturation they will migrate to the cell pole via tubulin structure. The tailocins will then be ejected in the medium with the cell lysis. They can be projected up to several tens of micrometers thanks to a very high turgor pressure of the cell. The tailocins released will then recognize and bind to the kin bacteria to kill them.<ref>{{cite journal | vauthors = Vacheron J, Heiman CM, Keel C| title = Live cell dynamics of production, explosive release and killing activity of phage tail-like weapons for Pseudomonas kin exclusion | journal = Communications Biology | volume = 87 | issue = 4 | date = January 2021 | page = 87 | doi =10.1038/s42003-020-01581-1 | pmid = 33469108 | pmc = 7815802 }}</ref>