Journal article
TonB Interacts with Nonreceptor Proteins in the Outer Membrane of Escherichia coli
Journal of bacteriology, Vol.184(6), pp.1640-1648
03/2002
Handle:
https://hdl.handle.net/2376/100632
PMCID: PMC134908
PMID: 11872715
Abstract
The
Escherichia coli
TonB protein serves to couple the cytoplasmic membrane proton motive force to active transport of iron-siderophore complexes and vitamin B
12
across the outer membrane. Consistent with this role, TonB has been demonstrated to participate in strong interactions with both the cytoplasmic and outer membranes. The cytoplasmic membrane determinants for that interaction have been previously characterized in some detail. Here we begin to examine the nature of TonB interactions with the outer membrane. Although the presence of the siderophore enterochelin (also known as enterobactin) greatly enhanced detectable cross-linking between TonB and the outer membrane receptor, FepA, the absence of enterochelin did not prevent the localization of TonB to the outer membrane. Furthermore, the absence of FepA or indeed of all the iron-responsive outer membrane receptors did not alter this association of TonB with the outer membrane. This suggested that TonB interactions with the outer membrane were not limited to the TonB-dependent outer membrane receptors. Hydrolysis of the murein layer with lysozyme did not alter the distribution of TonB, suggesting that peptidoglycan was not responsible for the outer membrane association of TonB. Conversely, the interaction of TonB with the outer membrane was disrupted by the addition of 4 M NaCl, suggesting that these interactions were proteinaceous. Subsequently, two additional contacts of TonB with the outer membrane proteins Lpp and, putatively, OmpA were identified by in vivo cross-linking. These contacts corresponded to the 43-kDa and part of the 77-kDa TonB-specific complexes described previously. Surprisingly, mutations in these proteins individually did not appear to affect TonB phenotypes. These results suggest that there may be multiple redundant sites where TonB can interact with the outer membrane prior to transducing energy to the outer membrane receptors.
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Details
- Title
- TonB Interacts with Nonreceptor Proteins in the Outer Membrane of Escherichia coli
- Creators
- Penelope I Higgs - School of Molecular Biosciences, Washington State University, Pullman, Washington 99164-4233Tracy E Letain - School of Molecular Biosciences, Washington State University, Pullman, Washington 99164-4233Kelley K Merriam - School of Molecular Biosciences, Washington State University, Pullman, Washington 99164-4233Neal S Burke - School of Molecular Biosciences, Washington State University, Pullman, Washington 99164-4233HaJeung Park - School of Molecular Biosciences, Washington State University, Pullman, Washington 99164-4233ChulHee Kang - School of Molecular Biosciences, Washington State University, Pullman, Washington 99164-4233Kathleen Postle - School of Molecular Biosciences, Washington State University, Pullman, Washington 99164-4233
- Publication Details
- Journal of bacteriology, Vol.184(6), pp.1640-1648
- Academic Unit
- Chemistry, Department of
- Publisher
- American Society for Microbiology
- Identifiers
- 99900546525901842
- Language
- English
- Resource Type
- Journal article