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. 1995 Aug 15;92(17):7946–7950. doi: 10.1073/pnas.92.17.7946

Features of MotA proton channel structure revealed by tryptophan-scanning mutagenesis.

L L Sharp 1, J Zhou 1, D F Blair 1
PMCID: PMC41263  PMID: 7644518

Abstract

The MotA protein of Escherichia coli is a component of the flagellar motors that functions in transmembrane proton conduction. Here, we report several features of MotA structure revealed by use of a mutagenesis-based approach. Single tryptophan residues were introduced at many positions within the four hydrophobic segments of MotA, and the effects on function were measured. Function was disrupted according to a periodic pattern that implies that the membrane-spanning segments are alpha-helices and that identifies the lipid-facing parts of each helix. The results support a hypothesis for MotA structure and mechanism in which water molecules form most of the proton-conducting pathway. The success of this approach in studying MotA suggests that it could be useful in structure-function studies of other integral membrane proteins.

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Selected References

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