Postle, Kathleen
Mail

Research Interests
Gram negative bacteria are surrounded by a double concentric membrane system--the cytoplasmic, or inner, membrane and the outer membrane. Dr. Postle’s lab is studying a form of signal transduction in Escherichia coli: the means by which cytoplasmic membrane energy (protonmotive force) is transduced to active transport proteins in the outer membrane by TonB protein. Current information indicates that energy is transduced by a series of conformational changes in TonB protein which are directly transmitted to the active transport proteins. An understanding of the molecular mechanism of TonB-dependent energy transduction would provide unique insights into all signal transduction processes. Furthermore, TonB-dependent systems are found in all Gram negative bacteria and the ability of bacterial pathogens to obtain iron is a TonB-dependent process. Since pathogens lacking TonB are compromised in their ability to cause disease, our understanding of the mechanism of TonB-dependent energy transduction could lead to the development of novel chemotherapeutics.

Publications
Postle, K. (1999) Active transport through customized _eta-barrels. Nature Structural Biology. 6:3-6.

Larsen, R. A., Thomas, M.G., and K. Postle. (1999) Protonmotive force, ExbB, and ligand-bound FepA drive conformational changes in TonB. Mol. Microbiol. 31:1809-1824.

Postle, K., and H. Vakharia (2000) TolC, a macromolecular periplasmic “chunnel”. Nature Structural Biology. 7:527-530.

Larsen, R.A., and K. Postle (2001) Conserved residues Ser16 and His20 and their relative positioning are essential for TonB activity, crosslinking of TonB with ExbB, and the ability of TonB to respond to proton motive force. J. Biol. Chem. 276:8111-8117.

Higgs, P.I., Letain, T.E., Merriam, K.K., Burke, N.S., Park, H., Kang, C. and K. Postle (2002) TonB interacts with non-receptor proteins in the outer membrane of Escherichia coli. J. Bacteriol. 184:1640.

Higgs, P.I., Larsen, R.A., and K. Postle (2002). Quantitation of known components of the Escherichia coli TonB energy transduction system: TonB, ExbB, ExbD, and FepA. Mol. Microbiol. 44:271-281.

Postle, K. (2002) Close before opening. Science 295:1658-1659.

Held, K. and K. Postle (2002) ExbB and ExbD do not function independently inTonB-dependent energy transduction. J. Bacteriol. 184:5170.

Vakharia, H. and K. Postle (2002) FepA with globular domain deletions lacks activity. J. Bacteriol. 184:5508.

Larsen, R.A., Letain, T.E., and K. Postle (2003) In vivo evidence of TonB shuttling between the cytoplasmic and outer membrane in Escherichia coli. Mol. Microbiol. 49: 211-218.

Larsen, R.A., Chen, G.J. and K. Postle (2003) Performance of standard phenotypic assays for TonB activity, as evaluated by varying the level of functional wild-type TonB. J. Bacteriol. 185:4699-4706.

Postle, K. and R.J. Kadner (2003) Touch and go: Tying TonB to transport. Mol. Microbiol. 49:869-882.

Ghosh, J. and K. Postle (2004) Evidence for dynamic clustering of carboxy terminal aromatic amino acids in TonB-dependent energy transduction. Mol. Microbiol 51:203-213.

Hilsenbeck, J.L., Park, H., Chen, G., Youn, B., Postle, K., and C. Kang. (2004) Crystal structure of the cytotoxic bacterial proteins colicin B at 2.5 Å resolution. Mol. Microbiol 51:711-720.