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Structures of the pleiotropic translational regulator Hfq and an Hfq–RNA complex: a bacterial Sm‐like protein
Author(s) -
Schumacher Maria A.,
Pearson Robert F.,
Møller Thorleif,
ValentinHansen Poul,
Brennan Richard G
Publication year - 2002
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/cdf322
Subject(s) - biology , regulator , bacterial protein , microbiology and biotechnology , rna , posttranslational modification , genetics , bacteria , biochemistry , gene , enzyme
In prokaryotes, Hfq regulates translation by modulating the structure of numerous RNA molecules by binding preferentially to A/U‐rich sequences. To elucidate the mechanisms of target recognition and translation regulation by Hfq, we determined the crystal structures of the Staphylococcus aureus Hfq and an Hfq–RNA complex to 1.55 and 2.71 Å resolution, respectively. The structures reveal that Hfq possesses the Sm‐fold previously observed only in eukaryotes and archaea. However, unlike these heptameric Sm proteins, Hfq forms a homo‐hexameric ring. The Hfq–RNA structure reveals that the single‐stranded hepta‐oligoribonucleotide binds in a circular conformation around a central basic cleft, whereby Tyr42 residues from adjacent subunits stack with six of the bases, and Gln8, outside the Sm motif, provides key protein–base contacts. Such binding suggests a mechanism for Hfq function.