| Author |
Kaminishi, Tatsuya Takemoto, Chie Fabbretti, Attilio Fucini, Paola Yokoyama, Shigeyuki Connell, Sean R. Gualerzi, Claudio O. Brandi, Letizia Giuliodori, Anna Maria Garofalo, Raffaella Schedlbauer, Andreas Ochoa-lizarralde, Borja |
| Description |
Author Affiliation: Fabbretti A ( Laboratory of Genetics, Department of Biosciences and Veterinary Medicine, University of Camerino, 62032 Camerino, Italy); Schedlbauer A ( Structural Biology Unit, Center for Cooperative Research in Biosciences, 48160 Derio, Bizkaia, Spain); Brandi L ( Laboratory of Genetics, Department of Biosciences and Veterinary Medicine, University of Camerino, 62032 Camerino, Italy); Kaminishi T ( Structural Biology Unit, Center for Cooperative Research in Biosciences, 48160 Derio, Bizkaia, Spain); Giuliodori AM ( Laboratory of Genetics, Department of Biosciences and Veterinary Medicine, University of Camerino, 62032 Camerino, Italy); Garofalo R ( Laboratory of Genetics, Department of Biosciences and Veterinary Medicine, University of Camerino, 62032 Camerino, Italy); Ochoa-Lizarralde B ( Structural Biology Unit, Center for Cooperative Research in Biosciences, 48160 Derio, Bizkaia, Spain); Takemoto C ( RIKEN Systems and Structural Biology Center, Yokohama 230-0045, Japan); Yokoyama S ( RIKEN Systems and Structural Biology Center, Yokohama 230-0045, Japan); Connell SR ( Structural Biology Unit, Center for Cooperative Research in Biosciences, 48160 Derio, Bizkaia, Spain); Gualerzi CO ( Laboratory of Genetics, Department of Biosciences and Veterinary Medicine, University of Camerino, 62032 Camerino, Italy); Fucini P ( Structural Biology Unit, Center for Cooperative Research in Biosciences, 48160 Derio, Bizkaia, Spain); |
| Abstract |
In prokaryotic systems, the initiation phase of protein synthesis is governed by the presence of initiation factors that guide the transition of the small ribosomal subunit (30S) from an unlocked preinitiation complex (30S preIC) to a locked initiation complex (30SIC) upon the formation of a correct codon–anticodon interaction in the peptidyl (P) site. Biochemical and structural characterization of GE81112, a translational inhibitor specific for the initiation phase, indicates that the main mechanism of action of this antibiotic is to prevent P-site decoding by stabilizing the anticodon stem loop of the initiator tRNA in a distorted conformation. This distortion stalls initiation in the unlocked 30S preIC state characterized by tighter IF3 binding and a reduced association rate for the 50S subunit. At the structural level we observe that in the presence of GE81112 the h44/h45/h24a interface, which is part of the IF3 binding site and forms ribosomal intersubunit bridges, preferentially adopts a disengaged conformation. Accordingly, the findings reveal that the dynamic equilibrium between the disengaged and engaged conformations of the h44/h45/h24a interface regulates the progression of protein synthesis, acting as a molecular switch that senses and couples the 30S P-site decoding step of translation initiation to the transition from an unlocked preIC to a locked 30SIC state. |
| Subject Keyword |
Anti-Bacterial Agents Chemistry Escherichia Coli Peptide Chain Initiation, Translational RNA, Bacterial RNA, Ribosomal, 16S RNA, Transfer Ribosome Subunits, Small, Bacterial Nucleic Acid Conformation Research Support, Non-U.S. Gov't Multidisciplinary |
