PubMed Health⌕ Search

Biomedical subjects

V D Vasiliev

Publications and source records attributed to V D Vasiliev.

At least 19 recordsLinked to original sources
PubMed2001

Structure of Cry3A delta-endotoxin within phospholipid membranes.

Interaction of delta-endotoxin and its proteolytic fragments with phospholipid vesicles was studied using electron microscopy, scanning microcalorimetry, and limited proteolysis. It was shown that native protein destroys liposomes. The removal of 4 N-terminal alpha-helices and the extreme 56 C-terminal amino acid residues did not affect this ability. The results obtained by limited proteolysis of delta-endotoxin bound to lipid vesicles show essential conformational changes in three or four N-terminal helices and in the C-terminal region. The calorimetric method used in this study provides a unique possibility for the validation of existing models of protein binding and for a more accurate determination of the regions where conformational changes take place. It was found that the binding of the protein to model liposomes does not alter its structure in the regions starting with the fourth alpha-helix of domain I. This can be concluded from the fact that the activation energy of denaturation of the protein remains unchanged upon its binding to the phospholipid membranes. A new structural model has been proposed which agrees with the data obtained.

Animals↗
PubMed1998

In vitro assembly of a ribonucleoprotein particle corresponding to the platform domain of the 30S ribosomal subunit.

A fragment of the 16S RNA of Thermus thermophilus corresponding to the central domain (nucleotides 547-895) has been prepared by transcription in vitro. Incubation of this fragment with the total 30S ribosomal proteins has resulted in the formation of a compact 12S ribonucleoprotein particle. This particle contained five T. thermophilus proteins corresponding to Escherichia coli ribosomal proteins S6, S8, S11, S15, and possibly S18, all of which were previously shown to interact with the central domain of the 16S RNA and to be localized in the platform (side bulge) of the 30S ribosomal subunit. When examined by electron microscopy, isolated particles have an appearance that is similar in size and shape to the corresponding morphological features of the 30S subunit. We conclude that the central domain of the 16S RNA can independently and specifically assemble with a defined subset of ribosomal proteins into a compact ribonucleoprotein particle corresponding to the platform (side bulge) of the 30S subunit.

Base Sequence↗
PubMed1990

Electron microscopy study of human myeloma immunoglobulin G1.

Human immunoglobulin G1 Van was studied by negative staining, freeze drying and high resolution shadow casting. The Fab and Fc subunits of an intact IgG1 molecule were shown to possess limited mobility. It was found that about 70% of molecules in the IgG1 Van specimen are not flat but have a tripod-like shape.

Humans↗
PubMed1989

Structure of the rat liver ribosome 40 S subunit: freeze-drying and high-resolution shadow casting.

Small ribosomal subunits from rat liver have been studied by electron microscopy using freeze-drying and high-resolution shadow casting. The absolute hand of the asymmetric subunit has been determined and its three-dimensional model with a 'right' location of the side protuberance has been constructed. The results evidence that pro- and eukaryotic ribosomes have a unique and principally similar structural organization.

Animals↗
PubMed1989

Localization of functional centers on the prokaryotic ribosome: immuno-electron microscopy approach.

Immuno-electron microscopy studies on the morphology of the Escherichia coli ribosome and the topography of its functional centers are summarized. A three-dimensional model of the ribosome with indications of the mRNA-binding site, the peptidyl-transferase center, the EF-Tu and EF-G-binding sites and the tRNA-binding sites in given. Thus, the mutual arrangement of the centers corresponding to the main functional activities of the ribosome during the process of translation is presented.

Binding Sites↗
PubMed1988

Electron microscopy study of Q beta replicase.

Purified preparations of Q beta replicase have been studied by electron microscopy using a negative staining technique, and a three-dimensional model of the enzyme molecule has been constructed. The molecule of this four-subunit protein appears to be a compact structure having a size of 100 +/- 10 A; it is subdivided into two unequal bipartite subparticles. The conclusion has been made that all the constituent subunits, including the ribosomal protein Sl, acquire a globular conformation when associated in the replicase complex.

Coliphages↗
PubMed1988

Does the channel for nascent peptide exist inside the ribosome? Immune electron microscopy study.

MS2 phage RNA-directed synthesis of an N-terminal polypeptide of the phage coat protein on Escherichia coli 70 S ribosomes was initiated in a cell-free system with the N-dinitrophenyl derivative of methionyl-tRNAFMet) and performed in the absence of tyrosine, lysine, cysteine and methionine. As a result, the translating ribosomes carried peptides up to 42 amino acid residues in length with the dinitrophenyl hapten at the N-ends. Using the immune electron microscopy technique the positions of the nascent peptide N-ends on the 70 S ribosomes have been visualized. It has been found that (i) the N-ends of nascent peptides of these lengths are accessible to antibodies, (ii) the exit site of a nascent peptide is the pocket between the base of the central protuberance and the L1 ridge on the 50 S subunit, i.e. presumably its peptidyl transferase center, and (iii) the further pathway of a nascent peptide seems to proceed along the groove on the external surface of the 50 S subunit.

Antibodies↗
PubMed1986

Structure of protein-deficient 50 S ribosomal subunits. Particles without 5 S RNA-protein complex retain the L7/L12 stalk and associate with 30 S subunits.

50 S ribosomal subunit derivatives without the 5 S RNA-protein complex obtained either by splitting with EDTA or by reconstitution from the 23 S RNA and proteins have been studied by electron microscopy. Removal of the 5 S RNA-protein complex is shown to affect neither the overall morphology of the larger ribosomal subunit nor the mode of its association with the small subunit.

Centrifugation, Density Gradient↗
PubMed1986

Localization of elongation factor Tu on the ribosome.

The EF-Tu-binding center of the E. coli ribosome has been localized by immunoelectron microscopy after cross-linking of the specific EF-Tu X 70 S ribosomal complex with dimethylsuberimidate. EF-Tu has been found to be in contact with the 50 S subunit in the region of the L7/L12 stalk and with the 30 S subunit in the upper part of its body on the side opposite the top of the ledge (the platform). The EF-Tu position on a model of the 70 S ribosome is presented.

Binding Sites, Antibody↗
PubMed1985

Fine structure of the 30 S ribosomal subunit.

Elongated hollow strands were revealed on raw images and averaged by the correlation method images of the 30 S subunit of the E. coli ribosome negatively stained by uranyl acetate. The tentative three-dimensional arrangement of the 'strands' and their nature are discussed.

Escherichia coli↗
PubMed1985

Topography of RNA in the ribosome: location of the 5 S RNA residues A39 and U40 on the central protuberance of the 50 S subunit.

The internal site of 5 S RNA comprising residues A39 and U40 has been localized on the E. coli 50 S ribosomal subunit by immune electron microscopy. It has been found to be located on the interface side of the central protuberance at the position distinctly apart but very close to the position of the 5 S RNA 3'-end providing evidence for a quite compact folded conformation of the 5 S RNA in situ.

Centrifugation, Density Gradient↗
PubMed1983

Structure of the Escherichia coli 50 S ribosomal subunit.

Freeze-dried and shadowed Escherichia coli 50 S ribosomal subunits have been examined by electron microscopy and a model of the subunit has been constructed. High resolution shadow casting has enabled us to determine independently the absolute hand of the subunit and to reveal some new structural features.

Escherichia coli↗
PubMed1983

Computer averaging of 50 S ribosomal subunit electron micrographs.

Micrographs of one of the views of the large Escherichia coli subunit negatively stained with uranyl acetate were computer averaged using two techniques: the maximum-likelihood method and the correlation method. In both cases, extremely similar images were obtained. The same fine structure of the subunit has also been observed using optical averaging.

Animals↗
PubMed1983

Structural study of translating 70 S ribosomes from Escherichia coli. I. Electron microscopy.

Translating 70 S ribosomes of Escherichia coli either in the pre-translocation or in the post-translocation state have been prepared by using the cell-free translation system in poly(U)-S-S-Sepharose columns [Methods Enzymol. (1979) 59, 382-398]. Electron microscopy study of the preparations has demonstrated that: (1) the mutual orientation of the ribosomal subunits in the translating ribosomes is the same as proposed by Lake for routine 30 S.50 S couples [J. Mol. Biol. (1976) 105, 111-130]; (2) the L7/L12 stalk of the 50 S subunit sticks out from the 70 S particle and does not join the 30 S subunit; (3) pre-translocation and post-translocation state ribosomes do not differ in mutual orientation of the subunits and in the position of the L7/L12 stalk, within the limits of electron microscopy resolution.

Cell-Free System↗
PubMed1983

Localization of 5' and 3' ends of the ribosome-bound segment of template polynucleotides by immune electron microscopy.

Poly(U) with an average chain length of 40-70 nucleotides was modified at the 5'- or 3'-terminal residues with 2,4-dinitrophenyl derivatives. The modified poly(U) was used to form 30S.poly(U) or 70S.poly(U).Phe-tRNA complexes. Localization of the 5' and 3' ends of the template polynucleotide on the 30S subunit and the 70S ribosome was performed by immune electron microscopy using antibodies against dinitrophenyl haptens. The 5' and 3' ends of poly(U) (putative entry and exit sites of the message) were found in the same region both on the 30S subunit and the 70S ribosome. They were located on the dorsal side of the 30S subunit between the head and the body near the groove bordering the side ledge (platform). Comparison of the size of this region with the possible length of the polynucleotide chain covered by the ribosome allowed us to suggest that the message makes a 'U-turn" (or forms a 'loop') as it passes through the ribosome.

Binding Sites↗