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Structural insights into the dynamics and function of the C-terminus of the E. coli RNA chaperone Hfq.

Beich-Frandsen M, Vecerek B, Konarev PV, Sjöblom B, Kloiber K, Hämmerle H, Rajkowitsch L, Miles AJ, Kontaxis G, Wallace BA, Svergun DI, Konrat R, Bläsi U, Djinovic-Carugo K - Nucleic Acids Res. (2011)

Bottom Line: These studies indicate that the C-termini are flexible and extend laterally away from the hexameric core, displaying in this way features typical of intrinsically disordered proteins that facilitate intermolecular interactions.We identified a minimal, intrinsically disordered region of the C-terminus supporting the interactions with longer RNA fragments.This minimal region together with rest of the C-terminal extension provides a flexible moiety capable of tethering long and structurally diverse RNA molecules.

View Article: PubMed Central - PubMed

Affiliation: Department of Structural and Computational Biology, Max F. Perutz Laboratories, University of Vienna, Campus Vienna Biocenter 5, A-1030 Vienna, Austria.

ABSTRACT
The hexameric Escherichia coli RNA chaperone Hfq (Hfq(Ec)) is involved in riboregulation of target mRNAs by small trans-encoded RNAs. Hfq proteins of different bacteria comprise an evolutionarily conserved core, whereas the C-terminus is variable in length. Although the structure of the conserved core has been elucidated for several Hfq proteins, no structural information has yet been obtained for the C-terminus. Using bioinformatics, nuclear magnetic resonance spectroscopy, synchrotron radiation circular dichroism (SRCD) spectroscopy and small angle X-ray scattering we provide for the first time insights into the conformation and dynamic properties of the C-terminal extension of Hfq(Ec). These studies indicate that the C-termini are flexible and extend laterally away from the hexameric core, displaying in this way features typical of intrinsically disordered proteins that facilitate intermolecular interactions. We identified a minimal, intrinsically disordered region of the C-terminus supporting the interactions with longer RNA fragments. This minimal region together with rest of the C-terminal extension provides a flexible moiety capable of tethering long and structurally diverse RNA molecules. Furthermore, SRCD spectroscopy supported the hypothesis that RNA fragments exceeding a certain length interact with the C-termini of Hfq(Ec).

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SRCD spectra of Hfq constructs. HfqEc65 (thin dotted line), HfqEc75 (thick dotted line), HfqEc85 (thin solid line), full-length HfqEc (thick solid line). The error bars represent one standard deviation between replicate scans.
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Figure 4: SRCD spectra of Hfq constructs. HfqEc65 (thin dotted line), HfqEc75 (thick dotted line), HfqEc85 (thin solid line), full-length HfqEc (thick solid line). The error bars represent one standard deviation between replicate scans.

Mentions: In order to study the secondary structure composition of the C-terminal extension of HfqEc in solution, we used synchrotron radiation circular dichroism (SRCD) spectroscopy. The additional data in the low-wavelength region accessible by this technique relative to that attainable in a conventional CD instrument is important for detecting natively-disordered types of secondary structure. The spectra of the protein constructs HfqEc65 (amino acids 1–65), HfqEc75 (amino acids 1–75), HfqEc85 (amino acids 1–85) and HfqEc (full-length, amino acids 1–102) collected under the same experimental conditions are shown in Figure 4.Figure 4.


Structural insights into the dynamics and function of the C-terminus of the E. coli RNA chaperone Hfq.

Beich-Frandsen M, Vecerek B, Konarev PV, Sjöblom B, Kloiber K, Hämmerle H, Rajkowitsch L, Miles AJ, Kontaxis G, Wallace BA, Svergun DI, Konrat R, Bläsi U, Djinovic-Carugo K - Nucleic Acids Res. (2011)

SRCD spectra of Hfq constructs. HfqEc65 (thin dotted line), HfqEc75 (thick dotted line), HfqEc85 (thin solid line), full-length HfqEc (thick solid line). The error bars represent one standard deviation between replicate scans.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3113564&req=5

Figure 4: SRCD spectra of Hfq constructs. HfqEc65 (thin dotted line), HfqEc75 (thick dotted line), HfqEc85 (thin solid line), full-length HfqEc (thick solid line). The error bars represent one standard deviation between replicate scans.
Mentions: In order to study the secondary structure composition of the C-terminal extension of HfqEc in solution, we used synchrotron radiation circular dichroism (SRCD) spectroscopy. The additional data in the low-wavelength region accessible by this technique relative to that attainable in a conventional CD instrument is important for detecting natively-disordered types of secondary structure. The spectra of the protein constructs HfqEc65 (amino acids 1–65), HfqEc75 (amino acids 1–75), HfqEc85 (amino acids 1–85) and HfqEc (full-length, amino acids 1–102) collected under the same experimental conditions are shown in Figure 4.Figure 4.

Bottom Line: These studies indicate that the C-termini are flexible and extend laterally away from the hexameric core, displaying in this way features typical of intrinsically disordered proteins that facilitate intermolecular interactions.We identified a minimal, intrinsically disordered region of the C-terminus supporting the interactions with longer RNA fragments.This minimal region together with rest of the C-terminal extension provides a flexible moiety capable of tethering long and structurally diverse RNA molecules.

View Article: PubMed Central - PubMed

Affiliation: Department of Structural and Computational Biology, Max F. Perutz Laboratories, University of Vienna, Campus Vienna Biocenter 5, A-1030 Vienna, Austria.

ABSTRACT
The hexameric Escherichia coli RNA chaperone Hfq (Hfq(Ec)) is involved in riboregulation of target mRNAs by small trans-encoded RNAs. Hfq proteins of different bacteria comprise an evolutionarily conserved core, whereas the C-terminus is variable in length. Although the structure of the conserved core has been elucidated for several Hfq proteins, no structural information has yet been obtained for the C-terminus. Using bioinformatics, nuclear magnetic resonance spectroscopy, synchrotron radiation circular dichroism (SRCD) spectroscopy and small angle X-ray scattering we provide for the first time insights into the conformation and dynamic properties of the C-terminal extension of Hfq(Ec). These studies indicate that the C-termini are flexible and extend laterally away from the hexameric core, displaying in this way features typical of intrinsically disordered proteins that facilitate intermolecular interactions. We identified a minimal, intrinsically disordered region of the C-terminus supporting the interactions with longer RNA fragments. This minimal region together with rest of the C-terminal extension provides a flexible moiety capable of tethering long and structurally diverse RNA molecules. Furthermore, SRCD spectroscopy supported the hypothesis that RNA fragments exceeding a certain length interact with the C-termini of Hfq(Ec).

Show MeSH
Related in: MedlinePlus