Sm-like proteins in Eubacteria: the crystal structure of the Hfq protein from Escherichia coli
AUTOR(ES)
Sauter, Claude
FONTE
Oxford University Press
RESUMO
The Hfq protein was discovered in Escherichia coli in the early seventies as a host factor for the Qβ phage RNA replication. During the last decade, it was shown to be involved in many RNA processing events and remote sequence homology indicated a link to spliceosomal Sm proteins. We report the crystal structure of the E.coli Hfq protein showing that its monomer displays a characteristic Sm-fold and forms a homo-hexamer, in agreement with former biochemical data. Overall, the structure of the E.coli Hfq ring is similar to the one recently described for Staphylococcus aureus. This confirms that bacteria contain a hexameric Sm-like protein which is likely to be an ancient and less specialized form characterized by a relaxed RNA binding specificity. In addition, we identified an Hfq ortholog in the archaeon Methanococcus jannaschii which lacks a classical Sm/Lsm gene. Finally, a detailed structural comparison shows that the Sm-fold is remarkably well conserved in bacteria, Archaea and Eukarya, and represents a universal and modular building unit for oligomeric RNA binding proteins.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=167641Documentos Relacionados
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