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A Yonath

Publications and source records attributed to A Yonath.

At least 55 records · Page 3Linked to original sources
PubMed1987

Three-dimensional image reconstruction from ordered arrays of 70S ribosomes.

A better understanding of the molecular mechanism of protein biosynthesis still awaits a reliable model for the ribosomal particle. We describe here the application of a diffraction technique, namely three-dimensional image reconstruction from two-dimensional sheets of 70S ribosomes from Bacillus stearothermophilus at 47 A resolution. The three-dimensional model obtained by these studies shows clearly the two subunits, the contact points between them, an empty space large enough to accommodate the components of protein biosynthesis, the location of regions rich in RNA and a possible binding site for mRNA. The tunnel within the 50S particle which may provide the path taken by the nascent polypeptide chain in partially resolved.

Geobacillus stearothermophilus↗
PubMed1987

Three-dimensional crystals of ribosomes and their subunits from eu- and archaebacteria.

Ordered three-dimensional crystals of 70S ribosomes as well as of 30S and 50S ribosomal subunits from various bacteria (E. coli, Bacillus stearothermophilus, Thermus thermophilus and Halobacterium marismortui) have been grown by vapour diffusion in hanging drops using mono- and polyalcohols. A new compact crystal form of 50S subunits has been obtained, and it is suitable for crystallographic studies at medium resolution. In addition, from one crystal form large crystals could be grown in X-ray capillaries. In all cases the crystals were obtained from functionally active ribosomal particles, and the particles from dissolved crystals retained their integrity and biological activity.

Archaea↗
PubMed1987

Reconstitution and crystallisation experiments with isolated split proteins from Bacillus stearothermophilus ribosomes.

Six proteins (B-L1, B-L6, B-L10, B-L11, B-L12 and B-L16) were removed from 50S ribosomal subunits of Bacillus stearothermophilus by treatment with ethanol and ammonium chloride. The proteins were isolated in a pure form, and one of them (B-L6) was crystallized. Five of the six proteins (in various combinations) were added back to the core particles, resulting in 50S subunits lacking one protein. The biological activities of these ribosomal particles as determined in the poly(U)-system varied over a wide range, depending on the protein which was omitted. The particles lacking one protein provide useful tools for heavy-atom derivation necessary for our crystallographic studies on the 50S subunits of Bacillus stearothermophilus.

Bacterial Proteins↗
PubMed1986

The growth of ordered two-dimensional sheets of 70 S ribosomes from Bacillus stearothermophilus.

Well ordered two-dimensional sheets of intact 70 S ribosomes from Bacillus stearothermophilus have been obtained in vitro using salt-alcohol mixtures. These sheets consist of relatively small unit cells with dimensions of 200 +/- 20 A and 400 +/- 30 A. Diffraction patterns of electron micrographs of these sheets stained with uranyl acetate contain features to 42 A resolution.

Geobacillus stearothermophilus↗
PubMed1986

Characterization of single crystals of the large ribosomal particles from a mutant of Bacillus stearothermophilus.

Single, three-dimensional crystals of 50 S ribosomal subunits, from a mutant of Bacillus stearothermophilus that lacks the protein L11, have been characterized using a synchrotron X-ray source. The crystals of the mutated particles grow under the same conditions and are isomorphous to those of the wild type of the same bacteria. They are orthorhombic, contain at least one 2-fold screw axis, and have unit cell dimensions of a = 350(+/- 10) A, b = 670(+/- 10) A, and c = 910(+/- 10) A. They diffract to 15 to 18 A resolution at 4 degrees C and are stable in the synchrotron beam for several hours.

Crystallography↗
PubMed1986

Characterization of single crystals of the large ribosomal particles from Bacillus stearothermophilus.

Single, three-dimensional crystals of the 50 S ribosomal subunit from Bacillus stearothermophilus (strain NCA) have been characterized using a synchrotron X-ray source. The crystals are orthorhombic with unit cell dimensions: a = 350 A, b = 670 A, c = 905 A, and contain at least one 2-fold screw axis. With cooling to -2 degrees C, the large crystals (1.0 mm X 0.2 mm X 0.1 mm) diffract to 15 to 18 A resolution and are stable in the synchrotron beam for several hours. Despite the large cell dimensions, the reflections are readily resolved when the X-ray diffraction patterns are densitometered with a 25 microns faster.

Crystallization↗
PubMed1984

Some x-ray diffraction patterns from single crystals of the large ribosomal subunit from Bacillus stearothermophilus.

X-ray diffraction patterns of three-dimensional crystals of the large ribosomal subunit from Bacillus stearothermophilus have been obtained using a synchrotron radiation beam. The patterns contain resolved diffraction spots and indicate packing in relatively small unit cells, the dimensions of which have been tentatively determined. The internal order of the crystals, as reflected in these patterns, has been correlated with the size, shape and conditions of growth of these crystals.

Geobacillus stearothermophilus↗
PubMed1984

Two-dimensional crystalline sheets of Bacillus stearothermophilus 50S ribosomal particles.

Two-dimensional crystalline sheets of the large ribosomal subunit from Bacillus stearothermophilus have been obtained using a slightly modified procedure to that for growing three-dimensional crystals of the same material. The crystalline subunits are packed within monolayers in a relatively small unit cell, the dimensions of which are closely related to those observed for two forms of the three-dimensional crystals. The packing symmetry is p121, and the optical diffraction patterns of micrographs of negatively stained crystals extend to approximately 3.0 nm.

Crystallization↗
PubMed1983

A compact three-dimensional crystal form of the large ribosomal subunit from Bacillus stearothermophilus.

A new form of well-ordered three-dimensional crystals of intact 50 S ribosomal subunits from Bacillus stearothermophilus have been obtained. Electron micrographs of positively stained sections of these crystals revealed that the ribosomal particles are packed closely. The cell parameters have been determined. Representative electron micrographs and their computed contoured filtered images are shown.

Crystallization↗
PubMed1983

Structural analysis of insulin determinants seen by T cells directed by H-2 genes.

The magnitude of the immune response of lymphocytes to defined antigenic determinants of ungulate insulins is controlled by the products of H-2 genes. Based on the crystallographically solved structure of porcine insulin, the close homology of all the ungulate insulins, and the amino acid substitutions, we built models of the different insulins. We analyzed the likely conformations of the antigenic determinants, and proposed structural specificities accounting for the immunologic phenomena observed.

Animals↗
PubMed1982

Parameters for crystal growth of ribosomal subunits.

A systematic analysis of the parameters that control the crystal growth of the large subunit of ribosomes from B stearothermophilus has been carried out. Several parameters have been identified and classified according to their significance. It was found that only biologically active particles can crystallize and that the critical period for the crystallization process is the first few days, during which changes in the volume and content of the crystallization drop are of importance for both nucleation and crystal growth. Consequently, an experimental procedure for fine control of these variables has been developed. As a result of these studies, the reproducibility of crystal formation was increased, and larger and more stable crystals have been obtained.

Bacillus↗