%0 Journal Article
%T Human Lsg1 defines a family of essential GTPases that correlates with the evolution of compartmentalization
%A Emmanuel G Reynaud
%A Miguel A Andrade
%A Fabien Bonneau
%A Thi Ly
%A Michael Knop
%A Klaus Scheffzek
%A Rainer Pepperkok
%J BMC Biology
%D 2005
%I BioMed Central
%R 10.1186/1741-7007-3-21
%X We describe the identification and characterization of a unique family of circularly permuted GTPases represented by the human orthologue of yeast Lsg1p. We placed the members of this family in the phylogenetic context of the YlqF Related GTPase (YRG) family, which are present in Eukarya, Bacteria and Archea and include the stem cell regulator Nucleostemin. To extend the computational analysis, we showed that hLsg1 is an essential GTPase predominantly located in the endoplasmic reticulum and, in some cells, in Cajal bodies in the nucleus. Comparison of localization and siRNA datasets suggests that all members of the family are essential GTPases that have increased in number as the compartmentalization of the eukaryotic cell and the ribosome biogenesis pathway have evolved.We propose a scenario, consistent with our data, for the evolution of this family: cytoplasmic components were first acquired, followed by nuclear components, and finally the mitochondrial and chloroplast elements were derived from different bacterial species, in parallel with the formation of the nucleolus and the specialization of nuclear components.Comparative genomics is a powerful method for identifying the potential functions of previously uncharacterized genes, allowing their distribution among the kingdoms of life to be characterized, and the changes in sequence and regulation underpinning their conserved or divergent functions to be tracked [1]. Comparative genomics has been enormously facilitated by progress in bioinformatics tools, comprising the enormous amount of information available from databases concerning protein localization [2,3], viability [4,5], protein expression [6], genetic interactions [7] and protein-protein interactions [8]. These resources are usually focused on one particular organism (S. cerevisiae, C. elegans, D. melanogaster or B. subtilis) and are therefore mainly used by the small part of the scientific community working with this organism and able to handle the o
%U http://www.biomedcentral.com/1741-7007/3/21