PROSITE documentation PDOC51706
EngB-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.

Within the translation factor-related (TRAFAC) class of P-loop GTPases, the EngB-type is widespread, but not ubiquitous in all three superkingdoms (missing, for example, from the Crenarchaeota, Caenorhabditis, and Drosophila). Proteins of the EngB-type GTPase family are involved in the biogenesis of ribosomes and are essential for the survival of a wide range of bacteria [1,2,3].

The EngB-type GTPase is comprised of a central β-sheet flanked by α-helices (see <PDB:1SUL>), in which semi-conserved residues involved in nucleotide binding are located in five motifs, called G1-G5. The G1 region (GxxxxGKS) forms the P-loop that is responsible for binding the phosphate groups of the guanine nucleotide. The G2 region corresponds to the switch I loop, which contains the consensus motif PGxT. The invariant threonine residue is responsible for binding a magnesium ion required for catalysis. The G3 region corresponds to the Walker B motif (DxxG), which forms part of switch II. The G4 (TKxD) and G5 motifs are involved in interactions with the guanine moiety of the substrate [2,3].

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

Last update:

February 2014 / First entry.


Technical section

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

G_ENGB, PS51706; EngB-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

2AuthorsRuzheinikov S.N. Das S.K. Sedelnikova S.E. Baker P.J. Artymiuk P.J. Garcia-Lara J. Foster S.J. Rice D.W.
TitleAnalysis of the open and closed conformations of the GTP-binding protein YsxC from Bacillus subtilis.
SourceJ. Mol. Biol. 339:265-278(2004).
PubMed ID15136032

3AuthorsChan K.-H. Wong K.-B.
TitleStructure of an essential GTPase, YsxC, from Thermotoga maritima.
SourceActa Crystallogr. F 67:640-646(2011).
PubMed ID21636901

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