3j5s | pdb_00003j5s
EttA binds to ribosome exit site and regulates translation by restricting ribosome and tRNA dynamics
Structural highlights
FunctionETTA_ECOLI A translation factor that gates the progression of the 70S ribosomal initiation complex (IC, containing tRNA(fMet) in the P-site) into the translation elongation cycle by using a mechanism sensitive to the ATP/ADP ratio. Binds to the 70S ribosome E-site where it modulates the state of the translating ribosome during subunit translocation. Stimulates dipeptide bond synthesis in the presence of ATP (cell in high energy state), but inhibits dipeptide synthesis in the presence of ADP (cell in low energy state), and thus may control translation in response to changing ATP levels (including during stationary phase). Following ATP hydrolysis is probably released allowing the ribosome to enter the elongation phase. ATPase activity is stimulated in the presence of ribosomes. Its specificity for the IC may be conferred by its recognition of features unique to tRNA(fMet).[1] [2] Publication Abstract from PubMedCells express many ribosome-interacting factors whose functions and molecular mechanisms remain unknown. Here, we elucidate the mechanism of a newly characterized regulatory translation factor, energy-dependent translational throttle A (EttA), which is an Escherichia coli representative of the ATP-binding cassette F (ABC-F) protein family. Using cryo-EM, we demonstrate that the ATP-bound form of EttA binds to the ribosomal tRNA-exit site, where it forms bridging interactions between the ribosomal L1 stalk and the tRNA bound in the peptidyl-tRNA-binding site. Using single-molecule fluorescence resonance energy transfer, we show that the ATP-bound form of EttA restricts ribosome and tRNA dynamics required for protein synthesis. This work represents the first example, to our knowledge, in which the detailed molecular mechanism of any ABC-F family protein has been determined and establishes a framework for elucidating the mechanisms of other regulatory translation factors. EttA regulates translation by binding the ribosomal E site and restricting ribosome-tRNA dynamics.,Chen B, Boel G, Hashem Y, Ning W, Fei J, Wang C, Gonzalez RL Jr, Hunt JF, Frank J Nat Struct Mol Biol. 2014 Jan 5. doi: 10.1038/nsmb.2741. PMID:24389465[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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