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Updated: Jun 3, 2026
10:41
Method to Measure Tone of Axial and Proximal Muscle
Published on: December 14, 2011
TonB or not TonB: is that the question?
Karla D Krewulak1, Hans J Vogel
1Biochemistry Research Group, Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada.
Summary
Bacteria scavenge iron using siderophores and outer membrane receptors. The TonB/ExbB/ExbD complex powers this transport, crucial for bacterial survival and nutrient uptake.
Area of Science:
- Microbiology
- Biochemistry
- Structural Biology
Background:
- Bacteria require iron for survival, often sequestering it from host proteins.
- Siderophores are key iron chelators secreted by bacteria.
- Gram-negative bacteria utilize specific outer membrane receptors for iron uptake.
Purpose of the Study:
- To review the structure and function of the TonB protein complex.
- To elucidate the mechanism of TonB-dependent energy transduction.
- To discuss the role of TonB in the transport of various substrates, including colicins.
Main Methods:
- Structural analysis of the TonB protein.
- Review of current models for TonB-mediated energy transduction.
- Examination of TonB's role in substrate transport.
Main Results:
- The TonB/ExbB/ExbD complex energizes substrate transport across the outer membrane.
- Outer membrane receptors exhibit diverse substrate specificities (siderophores, heme, vitamin B12, etc.).
- TonB plays a critical role in nutrient acquisition and colicin import.
Conclusions:
- The TonB complex is essential for active transport in Gram-negative bacteria.
- Understanding TonB's mechanism provides insights into bacterial iron metabolism and pathogenesis.
- TonB's function extends beyond iron uptake to include the transport of other molecules.
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