PDBsum entry 1cei

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Antibacterial protein PDB id
Protein chain
85 a.a. *
Waters ×60
* Residue conservation analysis
PDB id:
Name: Antibacterial protein
Title: Structure determination of the colicin e7 immunity protein (imme7) that binds specifically to the dnase-type colicin e7 and inhibits its bacteriocidal activity
Structure: Colicin e7 immunity protein. Chain: a. Synonym: imme7
Source: Escherichia coli. Organism_taxid: 562
1.80Å     R-factor:   0.187    
Authors: K.-F.Chak,M.K.Safo,W.-Y.Ku,S.-Y.Hsieh,H.S.Yuan
Key ref: K.F.Chak et al. (1996). The crystal structure of the immunity protein of colicin E7 suggests a possible colicin-interacting surface. Proc Natl Acad Sci U S A, 93, 6437-6442. PubMed id: 8692833
19-Mar-96     Release date:   12-Mar-97    
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Protein chain
Pfam   ArchSchema ?
Q03708  (IMM7_ECOLX) -  Colicin-E7 immunity protein
87 a.a.
85 a.a.
Key:    PfamA domain  Secondary structure  CATH domain

 Gene Ontology (GO) functional annotation 
  GO annot!
  Biological process     bacteriocin immunity   1 term 
  Biochemical function     protein binding     2 terms  


Proc Natl Acad Sci U S A 93:6437-6442 (1996)
PubMed id: 8692833  
The crystal structure of the immunity protein of colicin E7 suggests a possible colicin-interacting surface.
K.F.Chak, M.K.Safo, W.Y.Ku, S.Y.Hsieh, H.S.Yuan.
The immunity protein of colicin E7 (ImmE7) can bind specifically to the DNase-type colicin E7 and inhibit its bactericidal activity. Here we report the 1.8-angstrom crystal structure of the ImmE7 protein. This is the first x-ray structure determined in the superfamily of colicin immunity proteins. The ImmE7 protein consists of four antiparallel alpha-helices, folded in a topology similar to the architecture of a four-helix bundle structure. A region rich in acidic residues is identified. This negatively charged area has the greatest variability within the family of DNase-type immunity proteins; thus, it seems likely that this area is involved in specific binding to colicin. Based on structural, genetic, and kinetic data, we suggest that all the DNase-type immunity proteins, as well as colicins, share a "homologous-structural framework" and that specific interaction between a colicin and its cognate immunity protein relies upon how well these two proteins' charged residues match on the interaction surface, thus leading to specific immunity of the colicin.

Literature references that cite this PDB file's key reference

  PubMed id Reference
18074345 O.J.Clarke, and M.J.Parker (2008).
Time-averaged predictions of folded and misfolded peptides using a reduced physicochemical model.
  J Comput Chem, 29, 1177-1185.  
16434744 L.G.Doudeva, H.Huang, K.C.Hsia, Z.Shi, C.L.Li, Y.Shen, Y.S.Cheng, and H.S.Yuan (2006).
Crystal structural analysis and metal-dependent stability and activity studies of the ColE7 endonuclease domain in complex with DNA/Zn2+ or inhibitor/Ni2+.
  Protein Sci, 15, 269-280.
PDB codes: 1zns 1znv
16373474 R.J.Hosse, A.Rothe, and B.E.Power (2006).
A new generation of protein display scaffolds for molecular recognition.
  Protein Sci, 15, 14-27.  
16238427 B.Alakent, M.C.Camurdan, and P.Doruker (2005).
Hierarchical structure of the energy landscape of proteins revisited by time series analysis. I. Mimicking protein dynamics in different time scales.
  J Chem Phys, 123, 144910.  
15332910 B.Alakent, P.Doruker, and M.C.Camurdan (2004).
Application of time series analysis on molecular dynamics simulations of proteins: a study of different conformational spaces by principal component analysis.
  J Chem Phys, 121, 4759-4769.  
14962381 K.C.Hsia, K.F.Chak, P.H.Liang, Y.S.Cheng, W.Y.Ku, and H.S.Yuan (2004).
DNA binding and degradation by the HNH protein ColE7.
  Structure, 12, 205-214.
PDB code: 1pt3
12945054 H.Fan, and A.E.Mark (2003).
Relative stability of protein structures determined by X-ray crystallography or NMR spectroscopy: a molecular dynamics simulation study.
  Proteins, 53, 111-120.  
12441392 M.J.Sui, L.C.Tsai, K.C.Hsia, L.G.Doudeva, W.Y.Ku, G.W.Han, and H.S.Yuan (2002).
Metal ions and phosphate binding in the H-N-H motif: crystal structures of the nuclease domain of ColE7/Im7 in complex with a phosphate ion and different divalent metal ions.
  Protein Sci, 11, 2947-2957.
PDB code: 1mz8
  11045617 R.Boetzel, M.Czisch, R.Kaptein, A.M.Hemmings, R.James, C.Kleanthous, and G.R.Moore (2000).
NMR investigation of the interaction of the inhibitor protein Im9 with its partner DNase.
  Protein Sci, 9, 1709-1718.
PDB code: 1e0h
10574790 C.Li, D.Zhao, A.Djebli, and M.Shoham (1999).
Crystal structure of colicin E3 immunity protein: an inhibitor of a ribosome-inactivating RNase.
  Structure, 7, 1365-1372.
PDB code: 3eip
10368275 T.P.Ko, C.C.Liao, W.Y.Ku, K.F.Chak, and H.S.Yuan (1999).
The crystal structure of the DNase domain of colicin E7 in complex with its inhibitor Im7 protein.
  Structure, 7, 91.
PDB code: 7cei
10089452 U.C.Kühlmann, C.Kleanthous, R.James, G.R.Moore, and A.M.Hemmings (1999).
Preliminary X-ray crystallographic analysis of the complex between the DNAase domain of colicin E9 and its cognate immunity protein.
  Acta Crystallogr D Biol Crystallogr, 55, 256-259.  
9622349 C.Kleanthous, A.M.Hemmings, G.R.Moore, and R.James (1998).
Immunity proteins and their specificity for endonuclease colicins: telling right from wrong in protein-protein recognition.
  Mol Microbiol, 28, 227-233.  
10069005 J.Smarda, and D.Smajs (1998).
Colicins--exocellular lethal proteins of Escherichia coli.
  Folia Microbiol (Praha), 43, 563-582.  
9672039 K.F.Chak, S.Y.Hsieh, C.C.Liao, and L.Kan (1998).
Change of thermal stability of colicin E7 triggered by acidic pH suggests the existence of unfolded intermediate during the membrane-translocation phase.
  Proteins, 32, 17-25.  
9928481 M.A.Riley (1998).
Molecular mechanisms of bacteriocin evolution.
  Annu Rev Genet, 32, 255-278.  
9425068 R.Wallis, K.Y.Leung, M.J.Osborne, R.James, G.R.Moore, and C.Kleanthous (1998).
Specificity in protein-protein recognition: conserved Im9 residues are the major determinants of stability in the colicin E9 DNase-Im9 complex.
  Biochemistry, 37, 476-485.  
9718299 W.Li, S.J.Hamill, A.M.Hemmings, G.R.Moore, R.James, and C.Kleanthous (1998).
Dual recognition and the role of specificity-determining residues in colicin E9 DNase-immunity protein interactions.
  Biochemistry, 37, 11771-11779.  
9135159 S.Y.Hsieh, T.P.Ko, M.Y.Tseng, W.Ku, K.F.Chak, and H.S.Yuan (1997).
A novel role of ImmE7 in the autoregulatory expression of the ColE7 operon and identification of possible RNase active sites in the crystal structure of dimeric ImmE7.
  EMBO J, 16, 1444-1454.
PDB code: 1unk
The most recent references are shown first. Citation data come partly from CiteXplore and partly from an automated harvesting procedure. Note that this is likely to be only a partial list as not all journals are covered by either method. However, we are continually building up the citation data so more and more references will be included with time. Where a reference describes a PDB structure, the PDB codes are shown on the right.