Characterization of TonB interactions with the FepA cork domain and FecA N-terminal signaling domain.

The mechanism of TonB dependent siderophore uptake through outer membrane transporters in Gram-negative bacteria is poorly understood. In an effort to expand our knowledge of the interaction between TonB and the outer membrane transporters, we have cloned and expressed the FepA cork domain (11-154) from Salmonella typhimurium and characterized its interaction with the periplasmic C-terminal domain of TonB (103-239) by isotope assisted FTIR and NMR spectroscopy. For comparison we also performed similar experiments using the FecA N-terminal domain (1-96) from Escherichia coli which includes the conserved TonB box.