Structural similarity of ribosomes from E. coli and A. salina

1978 ◽  
Vol 36 (2) ◽  
pp. 242-243
Author(s):  
M. Boublik ◽  
R.M. Wydro ◽  
W. Hellmann ◽  
F. Jenkins
Keyword(s):  
Ribosomal Proteins ◽  
Direct Evidence ◽  
Structural Similarity ◽  
Carbon Support ◽  
Artemia Salina ◽  
Uranyl Acetate ◽  
Biological Assays ◽  
E Coli ◽  
And Function ◽  
Fine Carbon

Ribosomes are ribonucleoprotein particles necessary for processing the genetic information of mRNA into proteins. Analogy in composition and function of ribosomes from diverse species, established by biochemical and biological assays, implies their structural similarity. Direct evidence obtained by electron microscopy seems to be of increasing relevance in understanding the structure of ribosomes and the mechanism of their role in protein synthesis.The extent of the structural homology between prokaryotic and eukaryotic ribosomes has been studied on ribosomes of Escherichia coli (E.c.) and Artemia salina (A.s.). Despite the established differences in size and in the amount and proportion of ribosomal proteins and RNAs both types of ribosomes show an overall similarity. The monosomes (stained with 0.5% aqueous uranyl acetate and deposited on a fine carbon support) appear in the electron micrographs as round particles with a diameter of approximately 225Å for the 70S E.c. (Fig. 1) and 260Å for the 80S A.s. monosome (Fig. 2).

Structural Homology between Prokaryotic and Eukaryotic Ribosomes

1977 ◽  
Vol 35 ◽  
pp. 416-417
Author(s):  
M. Boublik ◽  
W. Hellmann ◽  
F. Jenkins
Keyword(s):  
Ribosomal Proteins ◽  
Critical Evaluation ◽  
Three Dimensional ◽  
Structural Complexity ◽  
Carbon Support ◽  
Uranyl Acetate ◽  
Three Dimensional Model ◽  
Ribonucleic Acids ◽  
E Coli ◽  
70S Ribosome

The structural complexity of ribosomes is evident from the large number of their constituents - ribosomal proteins and ribonucleic acids. The simplest known prokaryotic (70S) ribosome from E. coli is composed of 53 different proteins and three ribonucleic acid molecules (23S, 16S and 5S RNA). Eukaryotic (80S) ribosomes also consist of three RNAs (28S, 18S and 5S) but contain a higher number of proteins, approximately 70. The mutual interactions of ribosomal proteins and RNAs determine the final structure and thus the biological activity of the ribosome. As expected for particles with the above composition, ribosomes and both ribosomal subunits have no symmetry or repetition in structure.Electron micrographs of ribosomes (stained with 0.5% aqueous uranyl acetate and deposited on a fine carbon support) show distinct contours and electron dense pattern. Critical evaluation of different views of the two-dimensional projections of the ribosomal contours can provide a reasonable basis for proposing a three-dimensional model of the ribosome.

Structural Role of rRNAs on the Ribosomal Subunits from E. Coli by Scanning Transmission Electron Microscopy

1981 ◽  
Vol 39 ◽  
pp. 424-425
Author(s):  
M. Boublik ◽  
N. Robakis ◽  
J.S. Wall
Keyword(s):  
Three Dimensional ◽  
Uranyl Acetate ◽  
Dimensional Structure ◽  
Electron Microscopic ◽  
Ribosomal Subunits ◽  
E Coli ◽  
Freeze Dried ◽  
16S Rna ◽  
Scanning Transmission ◽  
And Function

The three-dimensional structure and function of biological supramolecular complexes are, in general, determined and stabilized by conformation and interactions of their macromolecular components. In the case of ribosomes, it has been suggested that one of the functions of ribosomal RNAs is to act as a scaffold maintaining the shape of the ribosomal subunits. In order to investigate this question, we have conducted a comparative TEM and STEM study of the structure of the small 30S subunit of E. coli and its 16S RNA.The conventional electron microscopic imaging of nucleic acids is performed by spreading them in the presence of protein or detergent; the particles are contrasted by electron dense solution (uranyl acetate) or by shadowing with metal (tungsten). By using the STEM on freeze-dried specimens we have avoided the shearing forces of the spreading, and minimized both the collapse of rRNA due to air drying and the loss of resolution due to staining or shadowing. Figure 1, is a conventional (TEM) electron micrograph of 30S E. coli subunits contrasted with uranyl acetate.

Conformation of Ribosomes from Escherichia Coli

1974 ◽  
Vol 32 ◽  
pp. 210-211
Author(s):  
M. Boublik ◽  
W. Hellmann ◽  
F. Jenkins
Keyword(s):  
Binding Sites ◽  
Ribosomal Proteins ◽  
Fluorescent Dyes ◽  
Protein Biosynthesis ◽  
Three Dimensional ◽  
Spatial Arrangement ◽  
Dimensional Structure ◽  
Complete Understanding ◽  
And Function

The present knowledge of the three-dimensional structure of ribosomes is far too limited to enable a complete understanding of the various roles which ribosomes play in protein biosynthesis. The spatial arrangement of proteins and ribonuclec acids in ribosomes can be analysed in many ways. Determination of binding sites for individual proteins on ribonuclec acid and locations of the mutual positions of proteins on the ribosome using labeling with fluorescent dyes, cross-linking reagents, neutron-diffraction or antibodies against ribosomal proteins seem to be most successful approaches. Structure and function of ribosomes can be correlated be depleting the complete ribosomes of some proteins to the functionally inactive core and by subsequent partial reconstitution in order to regain active ribosomal particles.

Ribosome Structural Organization

1974 ◽  
Vol 32 ◽  
pp. 332-333
Author(s):  
James A. Lake
Keyword(s):  
Ribosomal Proteins ◽  
Structural Organization ◽  
Three Dimensional ◽  
Small Subunit ◽  
Structural Studies ◽  
X Ray Diffraction ◽  
Specific Antibodies ◽  
X Ray ◽  
E Coli ◽  
Complete Sequences

The understanding of ribosome structure has advanced considerably in the last several years. Biochemists have characterized the constituent proteins and rRNA's of ribosomes. Complete sequences have been determined for some ribosomal proteins and specific antibodies have been prepared against all E. coli small subunit proteins. In addition, a number of naturally occuring systems of three dimensional ribosome crystals which are suitable for structural studies have been observed in eukaryotes. Although the crystals are, in general, too small for X-ray diffraction, their size is ideal for electron microscopy.

Sites of Adsorption of the Bacteriophages T3 and T5 on the Wall of Escherichia Coli B.

1967 ◽  
Vol 25 ◽  
pp. 96-97
Author(s):  
Manfred E. Bayer
Keyword(s):  
Escherichia Coli ◽  
Cell Wall ◽  
Electron Microscope ◽  
Uranyl Acetate ◽  
E Coli ◽  
Receptor Sites ◽  
Rigid Cell Wall ◽  
Host Cell Surface ◽  
Bacterial Viruses ◽  
Escherichia Coli B

Bacterial viruses adsorb specifically to receptors on the host cell surface. Although the chemical composition of some of the cell wall receptors for bacteriophages of the T-series has been described and the number of receptor sites has been estimated to be 150 to 300 per E. coli cell, the localization of the sites on the bacterial wall has been unknown.When logarithmically growing cells of E. coli are transferred into a medium containing 20% sucrose, the cells plasmolize: the protoplast shrinks and becomes separated from the somewhat rigid cell wall. When these cells are fixed in 8% Formaldehyde, post-fixed in OsO4/uranyl acetate, embedded in Vestopal W, then cut in an ultramicrotome and observed with the electron microscope, the separation of protoplast and wall becomes clearly visible, (Fig. 1, 2). At a number of locations however, the protoplasmic membrane adheres to the wall even under the considerable pull of the shrinking protoplast. Thus numerous connecting bridges are maintained between protoplast and cell wall. Estimations of the total number of such wall/membrane associations yield a number of about 300 per cell.

Depletion and Reconstitution of Active E. Coli Ribosomes

1975 ◽  
Vol 33 ◽  
pp. 640-641
Author(s):  
M. Boublik ◽  
W. Hellmann ◽  
F. Jenkins
Keyword(s):  
Protein Biosynthesis ◽  
Large Subunit ◽  
High Resolution Electron Microscopy ◽  
Small Subunit ◽  
Structure And Function ◽  
Biologically Active ◽  
Biological Macromolecules ◽  
E Coli ◽  
Resolution Electron ◽  
And Function

Correlations between structure and function of biological macromolecules have been studied intensively for many years, mostly by indirect methods. High resolution electron microscopy is a unique tool which can provide such information directly by comparing the conformation of biopolymers in their biologically active and inactive state. We have correlated the structure and function of ribosomes, ribonucleoprotein particles which are the site of protein biosynthesis. 70S E. coli ribosomes, used in this experiment, are composed of two subunits - large (50S) and small (30S). The large subunit consists of 34 proteins and two different ribonucleic acid molecules. The small subunit contains 21 proteins and one RNA molecule. All proteins (with the exception of L7 and L12) are present in one copy per ribosome.This study deals with the changes in the fine structure of E. coli ribosomes depleted of proteins L7 and L12. These proteins are unique in many aspects.

Protein-induced conformational changes in 16S rRNA during assembly of the Escherichia Coli 30S ribosomal subunit: A STEM study

1987 ◽  
Vol 45 ◽  
pp. 910-911
Author(s):  
M. Boublik ◽  
V. Mandiyan ◽  
J.F. Hainfeld ◽  
J.S. Wall
Keyword(s):  
16S Rrna ◽  
Conformational Changes ◽  
Ribosomal Proteins ◽  
Structural Changes ◽  
Ribosomal Subunit ◽  
Compact Structure ◽  
E Coli ◽  
Freeze Dried ◽  
16S Rna ◽  
30S Subunit

The aim of this study is to understand the mechanism of 16S rRNA folding into the compact structure of the small 30S subunit of E. coli ribosome. The assembly of the 30S E. coli ribosomal subunit is a sequence of specific interactions of 16S rRNA with 21 ribosomal proteins (S1-S21). Using dedicated high resolution STEM we have monitored structural changes induced in 16S rRNA by the proteins S4, S8, S15 and S20 which are involved in the initial steps of 30S subunit assembly. S4 is the first protein to bind directly and stoichiometrically to 16S rRNA. Direct binding also occurs individually between 16S RNA and S8 and S15. However, binding of S20 requires the presence of S4 and S8. The RNA-protein complexes are prepared by the standard reconstitution procedure, dialyzed against 60 mM KCl, 2 mM Mg(OAc)2, 10 mM-Hepes-KOH pH 7.5 (Buffer A), freeze-dried and observed unstained in dark field at -160°.

Role of the Small (40S) Subunits in the Structure of the Interface of Eukaryotic Ribosomes

1980 ◽  
Vol 38 ◽  
pp. 548-549
Author(s):  
M. Boublik ◽  
N. Robakis ◽  
W. Hellmann ◽  
F. Jenkins
Keyword(s):  
Structural Similarity ◽  
High Resolution Electron Microscopy ◽  
Peptide Bond ◽  
Uranyl Acetate ◽  
Mutual Orientation ◽  
Mutual Position ◽  
Peptide Bond Formation ◽  
Resolution Electron ◽  
Direct Technique ◽  
Structural Details

Ribosomes are ribonucleoprotein particles which process the genetic information coded in mRNA into protein synthesis. The analogy in function and composition of ribosomes from various sources, both prokaryotic and eukaryo-tic, imply a structural similarity. At present, high resolution electron microscopy is the most direct technique with a potential to resolve the extent of the structural homology of ribosomal particles at a macromolecular level. The structure of ribosomes is highly complex as a result of the large number of their constituents. In general, 80S eukaryotic monosomes consist of two uneven subunits - large (60S) and small (40S) - accomodating four different RNAs and approximately 80 different proteins. Mutual orientation of both subunits on the monosome is of particular interest because it determines the interface, the supposed site of interactions of ribosomes with other macro-molecules involved in peptide bond formation. Since entrapping of the contrasting solution (0.5% aqueous uranyl acetate) obscures all structural details in the interface, information on its architecture is limited to an indirect reconstruction based on the established 3-D structure of both sub-units and their mutual position after association.

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