The Native 3D Organization of Bacterial Polysomes
Autor: | Wolfgang Baumeister, Julio O. Ortiz, Stephanie A. Etchells, Adrian H. Elcock, Florian Brandt, F. Ulrich Hartl |
---|---|
Rok vydání: | 2009 |
Předmět: |
Models
Molecular Electron Microscope Tomography 0303 health sciences Messenger RNA PROTEINS Biochemistry Genetics and Molecular Biology(all) Cryoelectron Microscopy RNA Context (language use) Biology Ribosome General Biochemistry Genetics and Molecular Biology 03 medical and health sciences 0302 clinical medicine Biochemistry Polyribosomes Polysome Transfer RNA Prokaryotic translation Escherichia coli Biophysics Eukaryotic Ribosome 030217 neurology & neurosurgery 030304 developmental biology |
Zdroj: | Cell Cell; Vol 136 |
ISSN: | 0092-8674 |
DOI: | 10.1016/j.cell.2008.11.016 |
Popis: | SummaryRecent advances have led to insights into the structure of the bacterial ribosome, but little is known about the 3D organization of ribosomes in the context of translating polysomes. We employed cryoelectron tomography and a template-matching approach to map 70S ribosomes in vitrified bacterial translation extracts and in lysates of active E. coli spheroplasts. In these preparations, polysomal arrangements were observed in which neighboring ribosomes are densely packed and exhibit preferred orientations. Analysis of characteristic examples of polysomes reveals a staggered or pseudohelical organization of ribosomes along the mRNA trace, with the transcript being sequestered on the inside, the tRNA entrance sites being accessible, and the polypeptide exit sites facing the cytosol. Modeling of elongating nascent polypeptide chains suggests that this arrangement maximizes the distance between nascent chains on adjacent ribosomes, thereby reducing the probability of intermolecular interactions that would give rise to aggregation and limit productive folding. |
Databáze: | OpenAIRE |
Externí odkaz: |