Cell entry mechanism of enzymatic bacterial colicins: Porin recruitment and the thermodynamics of receptor binding

Housden, Nicholas G.; Loftus, Steven R.; Moore, Geoffrey R.; James, Richard; Kleanthous, Colin

doi:10.1073/pnas.0503567102

Cited by 90 publications

(163 citation statements)

References 36 publications

(40 reference statements)

Supporting

Mentioning

155

Contrasting

Order By: Relevance

“…Outer membrane protein F (OmpF) is the major porin in the outer membrane of Escherichia coli, where it forms trimeric channels for the passage of water, ions, sugars, polar nutrients and waste up to 700 Da in weight 5,6 . Diffusion in the membrane is an important factor in the function of OmpF as it has to be widely distributed on the cell surface for phage recognition 7 to occur, and also has to form a transient translocon with vitamin B 12 receptor BtuB for colicin import 8,9 .…”

mentioning

confidence: 99%

Characterization of the motion of membrane proteins using high-speed atomic force microscopy

et al. 2012

View full text Add to dashboard Cite

mentioning

confidence: 99%

Characterization of the motion of membrane proteins using high-speed atomic force microscopy

et al. 2012

View full text Add to dashboard Cite

“…From the result described above, it is hypothesized that the binding to BtuB is not sufficient to promote the release of the immunity protein from the bacteriocin complex. To cross the OM, the colicin N-terminal domain might recruit a porin (16). ColE2 uses preferentially OmpF as OM porin but can also use OmpC and PhoE (25).…”

Section: Synthesis Of Egfp-im2 Hybrid Proteinmentioning

confidence: 99%

“…During the uptake process the cognate immunity protein is dissociated from the colicin molecule, but how and exactly when this occurs is not known (20). Recently, Housden et al (16) have proposed that immunity protein of ColE9 is not released during association of the bacteriocin complex with its receptor BtuB and OmpF (16).…”

mentioning

confidence: 99%

Release of Immunity Protein Requires Functional Endonuclease Colicin Import Machinery

et al. 2006

View full text Add to dashboard Cite

Bacteria producing endonuclease colicins are protected against the cytotoxic activity by a small immunity protein that binds with high affinity and specificity to inactivate the endonuclease. This complex is released into the extracellular medium, and the immunity protein is jettisoned upon binding of the complex to susceptible cells. However, it is not known how and at what stage during infection the immunity protein release occurs. Here, we constructed a hybrid immunity protein composed of the enhanced green fluorescent protein (EGFP) fused to the colicin E2 immunity protein (Im2) to enhance its detection. The EGFP-Im2 protein binds the free colicin E2 with a 1:1 stoichiometry and specifically inhibits its DNase activity. The addition of this hybrid complex to susceptible cells reveals that the release of the hybrid immunity protein is a time-dependent process. This process is achieved 20 min after the addition of the complex to the cells. We showed that complex dissociation requires a functional translocon formed by the BtuB protein and one porin (either OmpF or OmpC) and a functional import machinery formed by the Tol proteins. Cell fractionation and protease susceptibility experiments indicate that the immunity protein does not cross the cell envelope during colicin import. These observations suggest that dissociation of the immunity protein occurs at the outer membrane surface and requires full translocation of the colicin E2 N-terminal domain.

show abstract

“…During the import process, when E-type nuclease colicinImm complexes bind to the cell surface receptor BtuB, their Imm protein dissociates from the bound colicin and is released into the external medium (10,11). The binding of the complex per se is however not enough to liberate the Imm protein.…”

mentioning

confidence: 99%

FtsH-dependent Processing of RNase Colicins D and E3 Means That Only the Cytotoxic Domains Are Imported into the Cytoplasm

Chauleau¹,

Mora²,

Serba

et al. 2011

Journal of Biological Chemistry

View full text Add to dashboard Cite

It has long been suggested that the import of nuclease colicins requires protein processing; however it had never been formally demonstrated. Here we show that two RNase colicins, E3 and D, which appropriate two different translocation machineries to cross the outer membrane (BtuB/Tol and FepA/TonB, respectively), undergo a processing step inside the cell that is essential to their killing action. We have detected the presence of the C-terminal catalytic domains of these colicins in the cytoplasm of target bacteria. The same processed forms were identified in both colicin-sensitive cells and in cells immune to colicin because of the expression of the cognate immunity protein. We demonstrate that the inner membrane protease FtsH is necessary for the processing of colicins D and E3 during their import. We also show that the signal peptidase LepB interacts directly with the central domain of colicin D in vitro and that it is a specific but not a catalytic requirement for in vivo processing of colicin D. The interaction of colicin D with LepB may ensure a stable association with the inner membrane that in turn allows the colicin recognition by FtsH. We have also shown that the outer membrane protease OmpT is responsible for alternative and distinct endoproteolytic cleavages of colicins D and E3 in vitro, presumably reflecting its known role in the bacterial defense against antimicrobial peptides. Even though the OmpT-catalyzed in vitro cleavage also liberates the catalytic domain from colicins D and E3, it is not involved in the processing of nuclease colicins during their import into the cytoplasm.Colicins are antibacterial toxins of Escherichia coli that are released into the extracellular medium in response to environmental stress conditions. Colicin D is an RNase that cleaves the anticodon loop of all four isoaccepting tRNA Arg (1). Colicin E3 cleaves 16 S ribosomal RNA (2). Both colicins provoke cell death by inactivating the protein biosynthetic machinery. Colicin producer cells are protected against both endogenous and exogenous toxin molecules by the constitutive expression of a cognate immunity (Imm) 3 protein, which forms a tight heterodimer complex with the nuclease domain of the colicin (3, 4).Colicin E3, like most colicins, has structurally identifiable N-terminal, central, and C-terminal domains. The first two domains are required for translocation and receptor binding, and they "hijack" certain functions of the target cell (i.e. the BtuB receptor and the Tol system) during colicin import. The C-terminal domain carries the cell-killing RNase function (5, 6). The colicin D protein has an unusual tripartite organization. The N-terminal domain is required for both the binding of the colicin to the high affinity, iron siderophore receptor FepA and for its subsequent translocation across the outer membrane. The 280-residue central domain is essential for uptake (and thus for cell killing), and it is also involved in the formation of the colicin D-ImmD protein complex (7). The passage of colicin D through th...

show abstract

Cell entry mechanism of enzymatic bacterial colicins: Porin recruitment and the thermodynamics of receptor binding

Cited by 90 publications

References 36 publications

Characterization of the motion of membrane proteins using high-speed atomic force microscopy

Characterization of the motion of membrane proteins using high-speed atomic force microscopy

Release of Immunity Protein Requires Functional Endonuclease Colicin Import Machinery

FtsH-dependent Processing of RNase Colicins D and E3 Means That Only the Cytotoxic Domains Are Imported into the Cytoplasm

Contact Info

Product

Resources

About