8.B.24 The Colicin Immunity Protein (ColIP) Functional Family 

Proteins conferring immunity against pore-forming colicins are localized in the E. coli inner membrane. Their protective effects are mediated by direct interaction with the C-terminal domain of their cognate colicins. Cai, the immunity protein protecting E. coli against colicin A, contains four cysteine residues. Cai forms homodimers with four TMSs per subunit, and dimerization occurs via the third TMS. Co-expression of Cai with its target, the colicin A pore-forming domain (pfColA), in the inner membrane prevents the formation of intermolecular and intramolecular disulfide bonds, indicating that pfColA interacts with the dimer of Cai and modifies its conformation. When Cai is locked by disulfide bonds, it is no longer able to protect cells against colicin A (Zhang et al. 2010).

This family includes several subfamilies with very different protein sizes, topologies (from 0 to 4 TMSs) and sequences, and their target proteins inhibit colicins that act in very different ways.  Homology between members of these different subfamilies has not been established, so the ColIP family should be consider to be a functional superfamily. 


 

References:

Ghequire, M.G., L. Kemland, E. Anoz-Carbonell, S.K. Buchanan, and R. De Mot. (2017). A Natural Chimeric Pseudomonas Bacteriocin with Novel Pore-Forming Activity Parasitizes the Ferrichrome Transporter. MBio 8:.

Knowling, S.E., A.M. Figueiredo, S.B. Whittaker, G.R. Moore, and S.E. Radford. (2009). Amino acid insertion reveals a necessary three-helical intermediate in the folding pathway of the colicin E7 immunity protein Im7. J. Mol. Biol. 392: 1074-1086.

Smajs, D., P. Matejková, and G.M. Weinstock. (2006). Recognition of pore-forming colicin Y by its cognate immunity protein. FEMS Microbiol. Lett. 258: 108-113.

Usón, I., S.I. Patzer, D.D. Rodríguez, V. Braun, and K. Zeth. (2012). The crystal structure of the dimeric colicin M immunity protein displays a 3D domain swap. J Struct Biol 178: 45-53.

Wertz, J.E. and M.A. Riley. (2004). Chimeric nature of two plasmids of Hafnia alvei encoding the bacteriocins alveicins A and B. J. Bacteriol. 186: 1598-1605.

Zhang, X.Y., R. Lloubès, and D. Duché. (2010). Channel domain of colicin A modifies the dimeric organization of its immunity protein. J. Biol. Chem. 285: 38053-38061.

Examples:

TC#NameOrganismal TypeExample
8.B.24.1.1

Colicin immunity protein of 178 aas and 4 TMSs; 61 % identical to Cai of  E. coli which also has 4 TMSs (Zhang et al. 2010).

Proteobacteria

Colicin immunity protein of Citrobacter freundii

 
8.B.24.1.2

Colicin N immunity Protein of 131 aas and 3 or 4 TMSs

Proteobacteria

Imm of E. coli

 
8.B.24.1.3

Putative Colicin Immunity protein of 148 aas and 4 TMSs.

Proteobacteria

Imm of Providencia alcalifaciens

 
8.B.24.1.4

Immunity protein, ImnH, of 184 aas and 4 TMSs; provides immunity to the colicin-like pore-forming domain protein, PmnH (TC#1.C.1.3.6) (Ghequire et al. 2017).

ImnH of Pseudomonas synxantha

 
8.B.24.1.5

Colicin U immunity protein, Cui, of 174 aas and 4 TMSs (Smajs et al. 2006).

Cui of Shigella boydii

 
Examples:

TC#NameOrganismal TypeExample
8.B.24.2.1

Colicin Ib immunity protein of 127 aas and 3 TMSs, Imm.

Proteobacteria

Imm of E. coli

 
8.B.24.2.2
Alveicin A immunity protein of 111 aas and 3 TMSs (Wertz and Riley 2004).

Proteobacteria

Alveicin A immunity protein of Hafnia alvei
 
8.B.24.2.3

Uncharacted protein of 103 aas and 3 TMSs

Proteobacteria

UP of Aeromonas hydrophila

 
8.B.24.2.4

Uncharacterized protein of 131 aas and 3 TMSs

Proteobacteria

UP of Aggregatibacter actinomycetemcomitans

 
8.B.24.2.5

Uncharacterized protein of 117 aas and 4 TMSs

Proteobacteria

UP of Salmonella enterica subsp. enterica serovar Tallahassee

 
8.B.24.2.6

Colicin immunity protein of 119 aas and 3 TMSs, Imm.

Proteobacteria

Imm of E. coli

 
Examples:

TC#NameOrganismal TypeExample
8.B.24.3.1

Colicin M Immunity Protein of 141 aas and 1 TMSs. Cmi.  This protein is able to protect a cell that harbors the plasmid ColBM-Cl139 encoding colicin M, against colicin M.  Colicin M (Cma) is inactivated by interaction with Cmi. The structure of Cmi has been solved at a resolution of 1.95Å. The monomeric structure consists of a long N-terminal α-TMS and a four-stranded C-terminal β-sheet. Dimerization is mediated by an extended interface of hydrogen bond interactions between the α-helix and the four-stranded β-sheet of the symmetry related molecule. Two intermolecular disulfide bridges covalently connect this dimer to lock this complex (Usón et al. 2012).

Proteobacteria

Cmi of E. coli

 
8.B.24.3.2

YebF homologue of 119 aas and 1 TMS.

Proteobacteria

YebF homologue of Hafnia alvei

 
8.B.24.3.3

Uncharacterized protein of 113 aas and 1 TMS.

Proteobacteria

UP of Salmonella enterica

 
Examples:

TC#NameOrganismal TypeExample
8.B.24.4.1

Colicin E3 immunity protein of 85 aas and 0 TMSs, Imm3, Imm, ImmB, CeiC. 

Proteobacteria

ImmB (CeiC) of E. coli

 
8.B.24.4.2

Cloacin of 92 aas and 0 TMSs.

Proteobacteria

Cloacin of Pseudomonas fluorescens

 
8.B.24.4.3

Uncharacterized protein of 79 aas and 0 TMSs

Cyanobacteria

UP of Synechococcus sp.

 
Examples:

TC#NameOrganismal TypeExample
8.B.24.5.1

Colicin E8 immunity protein of 85 aas and 0 TMSs.

Proteobacteria

Imm of E. coli

 
8.B.24.5.2

Pyocin S2 immunity protein of 86 aas

Proteobacteria

Pyocin immunity protein of Pseudomonas plecoglossicida

 
8.B.24.5.3

bacteriocin immunity protein of 83 aas and 0 TMSs

Proteobacteria

Immunity protein of Acaryochloris marina

 
8.B.24.5.4

Uncharacterized protein of 83 aas and 0 TMSs

Actinobacteria

UP of Streptomyces gancidicus

 
8.B.24.5.5

Colicin E7 immunity protein of 87 aas, Imm; Im7; CeiE7 (Knowling et al. 2009).

Proteobacteria

Imm or CeiE7 of E. coli