In vivo inhibition of TonB-dependent processes by a TonB box consensus pentapeptide

Tuckman, Margareta; Osburne, Marcia S.

doi:10.1128/jb.174.1.320-323.1992

Cited by 55 publications

(37 citation statements)

References 18 publications

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“…The TonB box on the FecAЈ(1-127) fragment did not interfere with energization of outer membrane ferric citrate transport by TonB. As a pentapeptide derived from the TonB box of FhuE inhibits TonB-dependent receptor activities ( Tuckman and Osburne, 1992), we assume that the TonB box of FecAЈ (1-127) is shielded by the peptide, or is forced into an inactive conformation so that it does not inhibit interaction of TonB with wild-type FecA.…”

Section: Discussionmentioning

confidence: 95%

Transcription induction of the ferric citrate transport genes via the N‐terminus of the FecA outer membrane protein, the Ton system and the electrochemical potential of the cytoplasmic membrane

Kim

Stiefel

Plantor

et al. 1997

Molecular Microbiology

134

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Section: Discussionmentioning

confidence: 95%

Transcription induction of the ferric citrate transport genes via the N‐terminus of the FecA outer membrane protein, the Ton system and the electrochemical potential of the cytoplasmic membrane

Kim

Stiefel

Plantor

et al. 1997

Molecular Microbiology

134

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“…N-terminal sequences of FhuA might be exposed to the periplasm, since the cytoplasmic membrane-anchored TonB protein is thought to physically interact with FhuA and with other TonB-dependent OM receptors through the TonB box located near their N termini. Furthermore, TonB-dependent transport processes were inhibited by a soluble, synthetic TonB box consensus pentapeptide (44). In FhuA, the TonB box includes residues 7 to 11 (11).…”

Section: Discussionmentioning

confidence: 99%

Topological analysis of the Escherichia coli ferrichrome-iron receptor by using monoclonal antibodies

1995

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Ferrichrome-iron transport inThe uptake of ferric siderophores and vitamin B 12 across the outer membrane (OM) of gram-negative bacteria is driven by a poorly understood energy-coupled mechanism which involves the cytoplasmic membrane-associated proteins TonB, ExbB, and ExbD (reviewed in references 21, 26, 33). TonBdependent transport systems are characterized by OM receptors with high affinity and substrate specificity for their cognate siderophore or for vitamin B 12 . There are additional requirements for proteins within the periplasm and in the cytoplasmic membrane to complete the transport process of siderophore or vitamin B 12 . The Escherichia coli OM receptor for ferrichrome-iron is FhuA (M r , 78,992; 714 amino acids [11]), a protein which also acts as the receptor for phages T1, T5, UC-1, and 80, for colicin M, and for the peptide antibiotics albomycin and microcin 25. The periplasmic binding protein FhuD (5, 10) and the cytoplasmic membrane-associated proteins FhuB and FhuC are required for internalization of hydroxamate siderophores (reviewed in reference 3). FhuB and FhuC display characteristics of binding protein-dependent ATP-binding cassette transporters (18).A prerequisite to understanding the mechanism of active transport of ferrichrome-iron is to understand the molecular organization of FhuA within the OM. As with other OM proteins (OMPs), amphiphilic sequences of FhuA are thought to constitute membrane-spanning beta sheets, while intervening sequences (which often display a strongly hydrophilic character) probably form extramembranous loops. Experimental evidence generally supports these structural predictions and has provided some basis on which to model the topological organization of FhuA. Insertions of tetra-to hexadecapeptides at some sites within FhuA induced susceptibility to exogenously added proteases (28). Differential protease susceptibility of the insertion mutant FhuAs in whole cells as opposed to spheroplasts led to a prediction of the transmembrane arrangement of FhuA (28). Cells expressing FhuA⌬Asp-348 demonstrated reduced sensitivity to killing by phage T5 and complete resistance to T1, 80, and colicin M (23). These data supported the proposed cell surface exposure of a loop containing amino acids 316 to 356 of FhuA. Excision of amino acids 322 to 355 from FhuA transformed the ferrichrome-specific active transporter into a protein which displayed characteristics of a TonBindependent channel: cells expressing FhuA⌬322-355 became sensitive to bacitracin and sodium dodecyl sulfate (SDS) and formed stable conductance channels in black lipid membranes (22). It was proposed that the transmembrane strands of FhuA assume the conformation of a large beta barrel, with the predicted loop of amino acids 316 to 356 forming a ''gate'' that somehow regulates ferrichrome transport through the channel (4, 22). Recently, Killmann et al. (24) identified amino acids within the proposed gating loop of FhuA which contribute to the binding of phages T1, T5, and 80 and of colicin M. Preincubation o...

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“…Thorough characterization of FhuA peptides which may inhibit FhuA-TonB coupling is now possible using our in vitro interaction assay. Such analyses should reveal the sequence specificity of the FhuA-TonB interaction if indeed it is uniquely dependent upon regions of FhuA primary sequence, as inferred from the results of Tuckman and Osburne (43).…”

Section: Discussionmentioning

confidence: 99%

Cell Envelope Signaling in Escherichia coli

Moeck

Coulton

Postle

1997

Journal of Biological Chemistry

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The ferrichrome-iron receptor of Escherichia coli is FhuA, an outer membrane protein that is dependent upon the energy-coupling protein TonB to enable active transport of specific hydroxamate siderophores, infection by certain phages, and cell killing by the protein antibiotics colicin M and microcin 25. In vivo cross-linking studies were performed to establish at the biochemical level the interaction between FhuA and TonB. In an E. coli strain in which both proteins were expressed from the chromosome, a high molecular mass complex was detected when the ferrichrome homologue ferricrocin was added immediately prior to addition of crosslinker. The complex included both proteins; it was absent from strains of E. coli that were devoid of either FhuA or TonB, and it was detected with anti-FhuA and anti-TonB monoclonal antibodies. These results indicate that, in vivo, the binding of ferricrocin to FhuA enhances complex formation between the receptor and TonB. An in vitro system was established with which to examine the FhuA-TonB interaction. Incubation of TonB with histidine-tagged FhuA followed by addition of Ni 2؉ -nitrilotriacetate-agarose led to the specific recovery of both TonB and FhuA. Addition of ferricrocin or colicin M to FhuA in this system greatly increased the coupling between FhuA and TonB. Conversely, a monoclonal antibody that binds near the N terminus of FhuA reduced the retention of TonB by histidine-tagged FhuA. These studies demonstrate the significance of ligand binding at the external surface of the cell to mediate signal transduction across the outer membrane.

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In vivo inhibition of TonB-dependent processes by a TonB box consensus pentapeptide

Cited by 55 publications

References 18 publications

Transcription induction of the ferric citrate transport genes via the N‐terminus of the FecA outer membrane protein, the Ton system and the electrochemical potential of the cytoplasmic membrane

Transcription induction of the ferric citrate transport genes via the N‐terminus of the FecA outer membrane protein, the Ton system and the electrochemical potential of the cytoplasmic membrane

Topological analysis of the Escherichia coli ferrichrome-iron receptor by using monoclonal antibodies

Cell Envelope Signaling in Escherichia coli

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