RNA Therapeutics Institute, Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, United States
Aviram Rasouly
Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, United States; Howard Hughes Medical Institute, New York University School of Medicine, New York, United States
Nikita Vasilyev
Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, United States
Vladimir Svetlov
Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, United States
Anna B Loveland
RNA Therapeutics Institute, Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, United States
Ruben Diaz-Avalos
Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, United States; Howard Hughes Medical Institute, New York University School of Medicine, New York, United States
RNA Therapeutics Institute, Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, United States
In bacteria, mRNA transcription and translation are coupled to coordinate optimal gene expression and maintain genome stability. Coupling is thought to involve direct interactions between RNA polymerase (RNAP) and the translational machinery. We present cryo-EM structures of E. coli RNAP core bound to the small ribosomal 30S subunit. The complex is stable under cell-like ionic conditions, consistent with functional interaction between RNAP and the 30S subunit. The RNA exit tunnel of RNAP aligns with the Shine-Dalgarno-binding site of the 30S subunit. Ribosomal protein S1 forms a wall of the tunnel between RNAP and the 30S subunit, consistent with its role in directing mRNAs onto the ribosome. The nucleic-acid-binding cleft of RNAP samples distinct conformations, suggesting different functional states during transcription-translation coupling. The architecture of the 30S•RNAP complex provides a structural basis for co-localization of the transcriptional and translational machineries, and inform future mechanistic studies of coupled transcription and translation.
