Primary Citation of Related Structures: 5UQ7, 5UQ8
PubMed Abstract:
Structured mRNAs positioned downstream of the ribosomal decoding center alter gene expression by slowing protein synthesis. Here, we solved the cryo-EM structure of the bacterial ribosome bound to an mRNA containing a 3' stem loop that regulates translation. Unexpectedly, the E-site tRNA adopts two distinct orientations. In the first structure, normal interactions with the 50S and 30S E site are observed. However, in the second structure, although the E-site tRNA makes normal interactions with the 50S E site, its anticodon stem loop moves ∼54 Å away from the 30S E site to interact with the 30S head domain and 50S uL5. This position of the E-site tRNA causes the uL1 stalk to adopt a more open conformation that likely represents an intermediate state during E-site tRNA dissociation. These results suggest that structured mRNAs at the entrance channel restrict 30S subunit movement required during translation to slow E-site tRNA dissociation.
Organizational Affiliation:
Life Sciences Institute and Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109, USA.
Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA.
Life Sciences Institute and Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109, USA. Electronic address: yiorgo@stanford.edu.
Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA. Electronic address: christine.m.dunham@emory.edu.
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