A model of the translational apparatus based on a three-dimensional reconstruction of theEscherichia coliribosome

The morphology of the Escherichia coli ribosome, i.e., its shape at moderate to low (20–40 Å (1 Å = 0.1 nm)) resolution, provides important constraints in modeling both the folding of ribosomal RNA and the translational process. A new reconstruction, obtained by low-dose cryoelectron microscopy and image processing of single ribosomes, contains clues to the way in which the ribosome interacts with the key functional ligands: the mRNA and the A- and P-site tRNAs. It also suggests possible pathways of the nascent polypeptide chain. From an interpretation of these clues in the light of existing knowledge, a plausible model for the locations and interactions of key components of protein synthesis is suggested.Key words: three-dimensional reconstruction, cryoelectron microscopy, messenger RNA, A- and P-site RNAs, exit tunnels.

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Three-dimensional reconstruction of Limulus polyphemus hemocyanin from cryoelectron microscopy

Journal of Molecular Biology ◽

10.1006/jmbi.1996.0840 ◽

1997 ◽

Vol 266 (5) ◽

pp. 1002-1015 ◽

Cited By ~ 10

Author(s):

Jean-Christophe Taveau ◽

Nicolas Boisset ◽

Josette Lamy ◽

Olivier Lambert ◽

Jean N Lamy

Keyword(s):

Three Dimensional ◽

Limulus Polyphemus ◽

Cryoelectron Microscopy ◽

Three Dimensional Reconstruction ◽

Dimensional Reconstruction

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Three-dimensional reconstruction of pericentromeric (1q12) DNA and ribosomal RNA sequences in HL60 cells after double-target in situ hybridization and confocal microscopy

Cytometry ◽

10.1002/cyto.990110504 ◽

1990 ◽

Vol 11 (5) ◽

pp. 579-585 ◽

Cited By ~ 7

Author(s):

H. van Dekken ◽

H. T. M. van der Voort ◽

G. J. Brakenhoff ◽

J. G. J. Bauman

Keyword(s):

In Situ Hybridization ◽

Confocal Microscopy ◽

Ribosomal Rna ◽

Three Dimensional ◽

Three Dimensional Reconstruction ◽

Rna Sequences ◽

Hl60 Cells ◽

Ribosomal Rna Sequences ◽

Dimensional Reconstruction

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Challenges of three-dimensional reconstruction of ribonucleoprotein complexes from electron spectroscopic images - Reconstructing ribosomal RNA

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100162727 ◽

1996 ◽

Vol 54 ◽

pp. 52-53

Author(s):

D.R. Beniac ◽

G.J. Czarnota ◽

T.A. Bartlett ◽

F.P. Ottensmeyer ◽

G. Harauz

Keyword(s):

Ribosomal Rna ◽

Correlation Functions ◽

Three Dimensional ◽

Three Dimensional Reconstruction ◽

Mutual Correlation ◽

Ribosomal Subunits ◽

E Coli ◽

Ribonucleoprotein Complexes ◽

Dimensional Reconstruction

Transmission electron microscopy has been dominant in structural studies of the ribosome and its constituent ribonucleic acids and proteins. Ribosomal RNA (rRNA) has central importance in the architecture of this complex and in protein synthesis. Our work has entailed using electron spectroscopic imaging (ESI) to probe the tertiary structure of rRNA in situ in a prokaryote (Escherichia coli) and in a eukaryote (Thermomyces lanuginosus). ESI uses only electrons which have lost a specific amount of energy due to specific inner-shell ionisation interactions with the specimen to form an elemental map. In nucleoprotein complexes, a map of the phosphorus distribution represents primarily a projection of the phosphate backbone of the nucleic acid component. The visualisation of rRNA in situ in the intact ribosomal subunit by ESI was demonstrated almost a decade ago to be feasible. Our work on quantitative image analysis of ES images of E. coli and Th. lanuginosus ribosomal subunits has presented unique challenges and has resulted in new algorithmic developments generally applicable to such images. These innovations include a singular pretreatment procedure, the use of mutual correlation functions rather than cross correlation functions to reduce the effect of low spatial frequency components, and angular determination using iterative quaternion-assisted angular reconstitution to compute a three-dimensional reconstruction. These investigations have produced direct information regarding ribosomal rRNA localisation in the ribosomal subunits of E. coli and Th. lanuginosus, and the position of non-conserved sequences.

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