Biochemistry

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Science  06 Feb 2004:
Vol. 303, Issue 5659, pp. 731
DOI: 10.1126/science.303.5659.731d

The Escherichia coli protein Hfq was first identified over three decades ago as a host factor necessary for the replication of the bacteriophage Qβ; Hfq appears to alter the secondary structure of the Qβ RNA. Viruses have streamlined their genomes by relying on the existing functions of host proteins, so it was not unexpected to find the abundant Hfq as a participant in the lives of host RNAs, promoting degradation in some instances, such as sodB mRNA, while enhancing the stability of small regulatory RNAs, such as RyhB, in others. Geissmann and Touati have mapped these interactions in detail and find that Hfq, like its Sm and Lsm cousins, binds to an AU-rich motif just upstream of the translation start site in sodB mRNA. One result of this interaction is the partial opening of the neighboring stem-loop that contains the initiator codon, which allows RyhB to gain access to a complementary 9-nucleotide sequence. Formation of the short double-stranded RNA region then leads to degradation of both RNAs in a pathway that may be shared by the many other iron metabolism transcripts targeted by RyhB. — GJC

EMBO J. 23, 396 (2004).

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