The membrane protein FeoB contains an intramolecular G protein essential for Fe(II) uptake in bacteria

Thomas C. Marlovits, Winfried Haase, Christian Herrmann, Stephen G. Aller, Vinzenz M. Unger*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

125 Scopus citations


G proteins are critical for the regulation of membrane protein function and signal transduction. Nevertheless, coupling between G proteins and membrane proteins with multiple membrane-spanning domains has so far been observed only in higher organisms. Here we show that the polytopic membrane protein FeoB, which is essential for Fe(II) uptake in bacteria, contains a guanine-nucleotide-specific nucleotide binding site. We identify the G4- motif, NXXD, responsible for guanine nucleotide specificity, and show that GTP hydrolysis occurs very slowly. In contrast to typical G proteins, the association and dissociation of GDP were found to be faster than for GTP, suggesting that in the absence of additional factors, FeoB's G protein domain may exist mostly in the GTP-bound form. Furthermore, the binding of GTP is required for efficient Fe(II) uptake through the FeoB-dependent system. Notably, even in bacteria, this covalent linkage between a G protein and a polytopic membrane protein appears, to our knowledge, to be unique. These findings raise the intriguing question whether FeoB represents a primordial archetype of G protein-regulated membrane proteins.

Original languageEnglish (US)
Pages (from-to)16243-16248
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number25
StatePublished - Dec 10 2002

ASJC Scopus subject areas

  • General


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