A colicin is a type of bacteriocin produced by and toxic to some strains of Escherichia coli. Colicins are released into the environment to reduce competition from other bacterial strains. Colicins bind to outer membrane receptors, using them to translocate to the cytoplasm or cytoplasmic membrane, where they exert their cytotoxic effect, including depolarisation of the cytoplasmic membrane, DNase activity, RNase activity, or inhibition of murein synthesis. Channel-forming colicins (colicins A, B, E1, Ia, Ib, and N) are transmembrane proteins that depolarize the cytoplasmic membrane, leading to dissipation of cellular energy. Most colicins are able to translocate the outer membrane by a two-receptor system, where one receptor is used for the initial binding and the second for translocation. The initial binding is to cell surface receptors such as the outer membrane proteins OmpF, FepA, BtuB, Cir and FhuA; colicins have been classified according to which receptors they bind to. The presence of specific periplasmic proteins, such as TolA, TolB, TolC, or TonB, are required for translocation across the membrane. Here you have my personal interpretation of a recent CryoEm structure of Colicin E1 fragment in nanodisc-embedded TolC (PDB code: 6WXI)
#molecularart ... #immolecular ... #colicin ... #bacteria ... #poreforming ... #translocation ... #CryoEM .... Rendered with @proteinimaging and finished with @corelphotopaint
#molecularart ... #immolecular ... #colicin ... #bacteria ... #poreforming ... #translocation ... #CryoEM .... Rendered with @proteinimaging and finished with @corelphotopaint
