Domain

FeoB-type guanine nucleotide-binding (G) domain (IPR030389)

Short name: G_FEOB_dom

Domain relationships

None.

Description

The P-loop 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 alpha-helical linker peptide to the membrane domain with 8 to 12 predicted membrane-spanning alpha-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 beta-sheet surrounded by five alpha-helices. The ~170-residue FeoB-type G domain harbours 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 stabilise the beta- and gamma-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 gamma-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 [PMID: 11916378, PMID: 19615379, PMID: 19629046, PMID: 20036663, PMID: 20123128, PMID: 20220129].

GO terms

Biological Process

No terms assigned in this category.

Molecular Function

GO:0005525 GTP binding

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.
CDD
PROSITE profiles
Pfam