The Hfq protein was discovered in Escherichia coli in the early seventies as a host factor for the Qbeta 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 ...
The Hfq protein was discovered in Escherichia coli in the early seventies as a host factor for the Qbeta 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.
Related Citations:
The Sm-Like Hfq Protein Increases Oxys RNA Interaction with Target Mrnas Zhang, A., Wassarman, K.M., Ortega, J., Steven, A.C., Storz, G. (2002) Mol Cell 9: 11
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Structures of the Pleiotropic Translational Regulator Hfq and an Hfq-RNA Complex: A Bacterial Sm-Like Protein Schumacher, M.A., Pearson, R.F., Moller, T., Valentin-Hansen, P., Brennan, R.G. (2002) EMBO J 21: 3546
Characterization of Broadly Pleiotropic Phenotypes Caused by an Hfq Insertion Mutation in Escherichia Coli K-12 Tsui, H.C., Leung, H.C., Winkler, M.E. (1994) Mol Microbiol 13: 35
Bacterial Proteins Required for Replication of Phage Q Ribonucleic Acid. Purification and Properties of Host Factor I, a Ribonucleic Acid-Binding Protein De Fernandez, M.T.F., Hayward, W.S., August, J.T. (1972) J Biol Chem 247: 824
Organizational Affiliation:
European Molecular Biology Laboratory, Structural and Computational Biology Programme, Meyerhofstrasse 1, D-69117 Heidelberg, Germany.
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