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Structural insights into a new homodimeric self‐activated GTPase family
Author(s) -
Gras Stéphanie,
Chaumont Valérie,
Fernandez Bernard,
Carpentier Philippe,
CharrierSavournin Fabienne,
Schmitt Sophie,
Pineau Charles,
Flament Didier,
Hecker Arnaud,
Forterre Patrick,
Armengaud Jean,
Housset Dominique
Publication year - 2007
Publication title -
embo reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.584
H-Index - 184
eISSN - 1469-3178
pISSN - 1469-221X
DOI - 10.1038/sj.embor.7400958
Subject(s) - gtpase , biology , nucleotide , signal recognition particle , genetics , microbiology and biotechnology , biochemistry , computational biology , gene , peptide sequence , signal peptide
The human XAB1/MBD in GTPase and its close homologues form one of the ten phylogenetically distinct families of the SIMIBI (after signal recognition particle, MinD and BioD) class of phosphate‐binding loop NTPases. The genomic context and the partners identified for the archaeal and eukaryotic homologues indicate that they are involved in genome maintenance—DNA repair or replication. The crystal structure of PAB0955 from Pyrococcus abyssi shows that, unlike other SIMIBI class G proteins, these highly conserved GTPases are homodimeric, regardless of the presence of nucleotides. The nucleotide‐binding site of PAB0955 is rather rigid and its conformation is closest to that of the activated SRP G domain. One insertion to the G domain bears a strictly conserved GPN motif, which is part of the catalytic site of the other monomer and stabilizes the phosphate ion formed. Owing to this unique functional feature, we propose to call this family as GPN‐loop GTPase.