ArticleJournal of molecular biology2012
ExbD mutants define initial stages in TonB energization.
Article in Journal of molecular biology, 2012. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 18 papers.
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Who cites it
18 citing papers in PubMed, 31 citations in OpenAlex.
- Bioinformatic discovery of type 11 secretion system (T11SS) cargo across theMicrobial genomics · 2025Article
- Energization of Outer Membrane Transport by the ExbB ExbD Molecular Motor.Journal of bacteriology · 2023Review
- Transcription regulation of iron carrier transport genes by ECF sigma factors through signaling from the cell surface into the cytoplasm.FEMS microbiology reviews · 2022Article
- The Intrinsically Disordered Region of ExbD Is Required for Signal Transduction.Journal of bacteriology · 2020Article
- Decoupling Filamentous Phage Uptake and Energy of the TolQRA Motor in Escherichia coli.Journal of bacteriology · 2020Article
- Lipid trafficking across the Gram-negative cell envelope.The Journal of biological chemistry · 2019Review
- The TonBJournal of bacteriology · 2019Article
- Desert Dust as a Source of Iron to the Globally Important DiazotrophFrontiers in microbiology · 2017Article
- Article
- From Homodimer to Heterodimer and Back: Elucidating the TonB Energy Transduction Cycle.Journal of bacteriology · 2015Article
- Membrane Protein Complex ExbB4-ExbD1-TonB1 from Escherichia coli Demonstrates Conformational Plasticity.Journal of bacteriology · 2015Article
- ExbB cytoplasmic loop deletions cause immediate, proton motive force-independent growth arrest.Journal of bacteriology · 2013Article
- Overexpression of the Escherichia coli TolQ protein leads to a null-FtsN-like division phenotype.MicrobiologyOpen · 2013Article
- Mutations in Escherichia coli ExbB transmembrane domains identify scaffolding and signal transduction functions and exclude participation in a proton pathway.Journal of bacteriology · 2013Article
- Exploring the accessible conformations of N-terminal acetylated α-synuclein.FEBS letters · 2013Review
- Monomeric TonB and the Ton box are required for the formation of a high-affinity transporter-TonB complex.Biochemistry · 2013Article
- The ExbD periplasmic domain contains distinct functional regions for two stages in TonB energization.Journal of bacteriology · 2012Article
- Identification of functionally important TonB-ExbD periplasmic domain interactions in vivo.Journal of bacteriology · 2012Article
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Authors and funding
2 authors at 1 institution in 1 country.
Funding
Abstract
Cytoplasmic membrane proteins ExbB and ExbD of the Escherichia coli TonB system couple cytoplasmic membrane protonmotive force (pmf) to TonB. TonB transmits this energy to high-affinity outer membrane active transporters. ExbD is proposed to catalyze TonB conformational changes during energy transduction. Here, the effect of ExbD mutants and changes in pmf on TonB proteinase K sensitivity in spheroplasts was examined. Spheroplasts supported the pmf-dependent formaldehyde cross-link between periplasmic domains of TonB and ExbD, indicating that they constituted a biologically relevant in vivo system to study changes in TonB proteinase K sensitivity. Three stages in TonB energization were identified. In Stage I, ExbD L123Q or TonB H20A prevented proper interaction between TonB and ExbD, rendering TonB sensitive to proteinase K. In Stage II, ExbD D25N supported conversion of TonB to a proteinase-K-resistant form, but not energization of TonB or formation of the pmf-dependent formaldehyde cross-link. Addition of protonophores had the same effect as ExbD D25N. This suggested the existence of a pmf-independent association between TonB and ExbD. TonB proceeded to Stage III when pmf was present, again becoming proteinase K sensitive, but now able to form the pmf-dependent cross-link to ExbD. Absence or presence of pmf toggled TonB between Stage II and Stage III conformations, which were also detected in wild-type cells. ExbD also underwent pmf-dependent conformational changes that were interdependent with TonB. These observations supported the hypothesis that ExbD couples TonB to the pmf, with concomitant transitions of ExbD and TonB periplasmic domains from unenergized to energized heterodimers.
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