{PDOC51706}
{PS51706; G_ENGB}
{BEGIN}
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* EngB-type guanine nucleotide-binding (G) domain profile *
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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 beta-sheet flanked by alpha-
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.

-Sequences known to belong to this class detected by the profile: ALL.
-Other sequence(s) detected in Swiss-Prot: NONE.
-Last update: February 2014 / First entry.

[ 1] Leipe D.D., Wolf Y.I., Koonin E.V., Aravind L.
     "Classification and evolution of P-loop GTPases and related ATPases."
     J. Mol. Biol. 317:41-72(2002).
     PubMed=11916378; DOI=10.1006/jmbi.2001.5378
[ 2] Ruzheinikov S.N., Das S.K., Sedelnikova S.E., Baker P.J.,
     Artymiuk P.J., Garcia-Lara J., Foster S.J., Rice D.W.
     "Analysis of the open and closed conformations of the GTP-binding
     protein YsxC from Bacillus subtilis."
     J. Mol. Biol. 339:265-278(2004).
     PubMed=15136032; DOI=10.1016/j.jmb.2004.03.043
[ 3] Chan K.-H., Wong K.-B.
     "Structure of an essential GTPase, YsxC, from Thermotoga maritima."
     Acta Crystallogr. F 67:640-646(2011).
     PubMed=21636901; DOI=10.1107/S1744309111011651

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