| Group: Kristina Djinovic Carugo Bjoern Sjoeblom | Staff scientist Julius Kostan | Postdoc Claudia Schreiner | Technician Mads Beich-Frandsen | PhD Student Muhammad Bashir Khan | PhD Student Anita Salmazo | PhD Student Georg Mlynek | Diploma Student Christian Koncz I Diploma Student |
Structural Studies on RNA chaperone HFQ and its interactions with RNA
(SFB projects 1722)
Hfq is a nucleic acid-binding protein that functions as a global regulator of gene expression via its interactions with several small, non-coding RNA species. Hfq was originally identified as an E. coli host factor required for RNA phage Qß replication. Today it is known that it post-transcriptionally regulates bacterial gene expression by modulating both mRNA stability and translational activity, that it acts as an RNA chaperone on mRNAs as well as a virulence factor in several bacterial pathogens. The broad impact of the protein comes from its role in regulating the stability and/or translation of mRNAs from a number of genes that respond to environmental stress. Many regulatory noncoding RNAs, such as DsrA, OxyS, RprA, and Spot 42, require Hfq as an essential component in their regulation of mRNA translation.
A body of structural information generated by electron microscopy and X-ray diffraction methods on several bacterial Hfq proteins 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. A high resolution structure of a S. aureus Hfq in complex with a short of poly-U oligonucleotide revealed that the RNA binds in the inner rim of the hexamer.
Functional and structural studies on the full-length and C-terminally truncated E.coli Hfq have shown, that the aptamer adopts a Sm-like fold, and forms a donut-shaped hexamer. As shown by U. Blaesi’s group, the full-length molecule shows a higher binding affinity to the regulatory noncoding RNA DsrA, than the C-terminally truncated molecule, indicating that the C-terminus is actively involved in binding and/or recognition of the RNA. Our aim is to generate structural information on the E. coli Hfq and its complex with the minimum required segment of the regulatory noncoding RNA DsrA. In this effort are adopting an integrated structural biology approach, employing series of structural biology and complementary structural biology techniques/methods (NMR in collaboration with R. Konrat, SAXS in collaboration with D. Sverdun, EMBl-hamburg), with the macromolecular crystallography as the principal experimental technique whenever possible and suitable.
A body of structural information generated by electron microscopy and X-ray diffraction methods on several bacterial Hfq proteins 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. A high resolution structure of a S. aureus Hfq in complex with a short of poly-U oligonucleotide revealed that the RNA binds in the inner rim of the hexamer.
Functional and structural studies on the full-length and C-terminally truncated E.coli Hfq have shown, that the aptamer adopts a Sm-like fold, and forms a donut-shaped hexamer. As shown by U. Blaesi’s group, the full-length molecule shows a higher binding affinity to the regulatory noncoding RNA DsrA, than the C-terminally truncated molecule, indicating that the C-terminus is actively involved in binding and/or recognition of the RNA. Our aim is to generate structural information on the E. coli Hfq and its complex with the minimum required segment of the regulatory noncoding RNA DsrA. In this effort are adopting an integrated structural biology approach, employing series of structural biology and complementary structural biology techniques/methods (NMR in collaboration with R. Konrat, SAXS in collaboration with D. Sverdun, EMBl-hamburg), with the macromolecular crystallography as the principal experimental technique whenever possible and suitable.
Recent selected publications
Toro, I., Petrutz, C., Pacello, F., D'Orazio, M., Battistoni, A. & Djinovic-Carugo, K. (2009). Structural basis of heme binding in the Cu,Zn superoxide dismutase from Haemophilus ducreyi. J Mol Biol 386, 406-18.
Pinotsis, N., Abrusci, P., Djinovic-Carugo, K. & Wilmanns, M. (2009). Terminal assembly of sarcomeric filaments by intermolecular beta-sheet formation. Trends Biochem Sci 34, 33-9.
Macedo, S., Pechlaner, S., Schmid, W., Weik, M., Sato, K., Dennison, C. & Djinović-Carugo, K. (2009). Can soaked-in scavengers protect metalloprotein active sites from reduction during data collection? J Synchrotron Radiat In Press.
Sjoblom, B., Ylanne, J. & Djinovic-Carugo, K. (2008). Novel structural insights into F-actin-binding and novel functions of calponin homology domains. Curr Opin Struct Biol 18, 702-8.
Sjoblom, B., Salmazo, A. & Djinovic-Carugo, K. (2008). alpha-Actinin structure and regulation. Cell Mol Life Sci 65, 2688-701.