Caulobacter crescentus Hfq structure reveals a conserved mechanism of RNA annealing regulation.


No Thumbnail Available
Type
Article
Change log
Authors
Santiago-Frangos, Andrew 
Fröhlich, Kathrin S 
Jeliazkov, Jeliazko R 
Małecka, Ewelina M 
Abstract

We have solved the X-ray crystal structure of the RNA chaperone protein Hfq from the alpha-proteobacterium Caulobacter crescentus to 2.15-Å resolution, resolving the conserved core of the protein and the entire C-terminal domain (CTD). The structure reveals that the CTD of neighboring hexamers pack in crystal contacts, and that the acidic residues at the C-terminal tip of the protein interact with positive residues on the rim of Hfq, as has been recently proposed for a mechanism of modulating RNA binding. De novo computational models predict a similar docking of the acidic tip residues against the core of Hfq. We also show that C. crescentus Hfq has sRNA binding and RNA annealing activities and is capable of facilitating the annealing of certain Escherichia coli sRNA:mRNA pairs in vivo. Finally, we describe how the Hfq CTD and its acidic tip residues provide a mechanism to modulate annealing activity and substrate specificity in various bacteria.

Description
Keywords
Caulobacter, Hfq, RNA–protein interaction, natively unstructured protein, sRNA, Bacterial Proteins, Caulobacter crescentus, Crystallography, X-Ray, Host Factor 1 Protein, Models, Molecular, Molecular Chaperones, Protein Binding, RNA, Bacterial, RNA, Messenger, RNA, Small Untranslated
Journal Title
Proc Natl Acad Sci U S A
Conference Name
Journal ISSN
0027-8424
1091-6490
Volume Title
116
Publisher
Proceedings of the National Academy of Sciences
Rights
All rights reserved
Sponsorship
Wellcome Trust (200873/Z/16/Z)
SWH and BL are funded by the Wellcome Trust (200873/Z/16/Z). This work was also supported by the NIH (R01 GM120425 to SW, F31 GM123616 to JRJ, and R01 GM078221 to JJG). KF acknowledges funding by the LMU Mentoring program of the LMU Faculty of Biology.