PROSITE documentation PDOC51711
FeoB-type guanine nucleotide-binding (G) domain profile


The P-loop (see <PDOC00017>) guanosine triphosphatases (GTPases) control a multitude of biological processes, ranging from cell division, cell cycling, and signal transduction, to ribosome assembly and protein synthesis. GTPases exert their control by interchanging between an inactive GDP-bound state and an active GTP-bound state, thereby acting as molecular switches. The common denominator of GTPases is the highly conserved guanine nucleotide-binding (G) domain that is responsible for binding and hydrolysis of guanine nucleotides.

The FeoB family of GTPases is widespread, although not ubiquitous, in Bacteria and Archaea, but missing from Eukaryota. FeoB is involved in the uptake of ferrous iron (Fe(2+)), an important cofactor in biological electron transfer and catalysis. Most of the FeoB proteins contain an N-terminal G-domain, connected by an entirely α-helical linker peptide to the membrane domain with 8 to 12 predicted membrane-spanning α-helices, while in some organisms the G-domain is expressed separately as a soluble protein. The FeoB-type G domain belongs to the TrmE-Era-EngA-EngB-Septin-like (TEES) superfamily of the TRAFAC class GTPases.

The structure of the FeoB-type G domain follows the typical fold of small GTP-binding proteins, consisting of a seven-stranded β-sheet surrounded by five α-helices (see <PDB:3HYR>). The ~170-residue FeoB-type G domain harbors five short amino-acid motifs (G1-G5) that are critical in the binding of both a magnesium (Mg(2+)) ion and the guanine nucleotide. The G1 motif (GxxxxGKS/T) (P-loop) is in position to stabilize the β- and γ-phosphates of GTP by hydrogen bonds donated by main-chain amides. The threonine of the G2 motif (P/AGxT) coordinates the Mg(2+). The G3 motif (DxxG) interacts with the Mg(2+) and an oxygen of the γ-phosphate. The G4 motif (NxxD) is involved in recognition of the guanine nucleotide by forming hydrogen bonds to the guanine base. The G5 motif (S/VSTV]) is, despite low sequence conservation, attributed to critical guanine base coordination [1,2,3,4,5,6].

The profile we developed covers the entire FeoB-type G domain.

Last update:

April 2014 / Text revised.


Technical section

PROSITE method (with tools and information) covered by this documentation:

G_FEOB, PS51711; FeoB-type guanine nucleotide-binding (G) domain profile  (MATRIX)


1AuthorsLeipe D.D. Wolf Y.I. Koonin E.V. Aravind L.
TitleClassification and evolution of P-loop GTPases and related ATPases.
SourceJ. Mol. Biol. 317:41-72(2002).
PubMed ID11916378

2AuthorsKoester S. Wehner M. Herrmann C. Kuehlbrandt W. Yildiz O.
TitleStructure and function of the FeoB G-domain from Methanococcus jannaschii.
SourceJ. Mol. Biol. 392:405-419(2009).
PubMed ID19615379

3AuthorsGuilfoyle A. Maher M.J. Rapp M. Clarke R. Harrop S. Jormakka M.
TitleStructural basis of GDP release and gating in G protein coupled Fe2+ transport.
SourceEMBO J. 28:2677-2685(2009).
PubMed ID19629046

4AuthorsPetermann N. Hansen G. Schmidt C.L. Hilgenfeld R.
TitleStructure of the GTPase and GDI domains of FeoB, the ferrous iron transporter of Legionella pneumophila.
SourceFEBS Lett. 584:733-738(2010).
PubMed ID20036663

5AuthorsHung K.-W. Chang Y.-W. Eng E.T. Chen J.-H. Chen Y.-C. Sun Y.-J. Hsiao C.-D. Dong G. Spasov K.A. Unger V.M. Huang T.-H.
TitleStructural fold, conservation and Fe(II) binding of the intracellular domain of prokaryote FeoB.
SourceJ. Struct. Biol. 170:501-512(2010).
PubMed ID20123128

6AuthorsAsh M.-R. Guilfoyle A. Clarke R.J. Guss J.M. Maher M.J. Jormakka M.
TitlePotassium-activated GTPase reaction in the G Protein-coupled ferrous iron transporter B.
SourceJ. Biol. Chem. 285:14594-14602(2010).
PubMed ID20220129

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