Formation of circular polyribosomes on eukaryotic mRNA without cap-structure and poly(A)-tail: a cryo electron tomography study

The polyribosomes newly formed on recombinant GFP-encoding mRNAs in a wheat germ cell-free translation system were analyzed using cryo-electron tomography, with sub-tomogram averaging of polysomal ribosomes and reconstruction of 3D structures of individual polyribosomes. The achieved level of resolution in the reconstructed polyribosomes allowed deducing the mRNA path by connecting adjacent exit and entry sites at the ribosomes inside each polyribosome. In this way, the circularity of a significant fraction (about 50%) of translating polyribosomes was proved in the case of the capped poly(A)-tailed mRNA, in agreement with the existing paradigm of the circularization via interaction of cap-bound initiation factor eIF4F with poly(A)-binding protein. However, translation of the capped mRNA construct without poly(A) tail, but with unspecific 3′-UTR derived from non-coding plasmid sequence, also led to the formation of circular polyribosomes in similar proportion (40%). Moreover, the polyribosomes formed on the uncapped non-polyadenylated mRNA with non-synergistic 5′- and 3′-UTRs proved to be circular as well, and appeared in the same proportion as in the previous cases. Thus, the formation of circular polyribosomes was found to be virtually independent of the presence of cap structure and poly(A) tail in mRNA, in contrast to the longstanding paradigm in the field.     

High-throughput cell-free systems for synthesis of functionally active proteins

Continuous cell-free translation systems with perpetual supply of consumable substrates and removal of reaction products made the process of in vitro synthesis of individual proteins sustainable and productive. Improvements of cell-free reaction mixtures, including new ways for efficient energy generation, had an additional impact on progress in cell-free protein synthesis technology. The requirement for gene-product identification in genomic studies, the development of high-throughput structural proteomics, the need for protein engineering without cell constraints (including the use of unnatural amino acids), and the need to produce cytotoxic, poorly expressed and unstable proteins have caused increased interest in cell-free protein synthesis technologies for molecular biologists, biotechnologists and pharmacologists.     

Effect of separate radioactive and chemical pollutants on the yield of cytogenetic disruptions in the intercalary meristem in spring barley

Dependencies of the yield of cytogenetic disturbances within intercalary meristem cells of spring barley on the soil level of 137Cs (1.48-14.8 MBq/m2), Cd, Pb (2-50 and 30-300 mg per kilogram of the soil) and 2.4-D herbicide (1 or 2 kg/ha) had a non-linear character in the studied range. At low concentrations the yield of cytogenetic disturbances grew faster than at higher ones. Concentrations of lead in soil (at the level of maximum concentration limit) and doses of 2.4-D recommended for agricultural use resulted in the increase in the rate of aberrant cells. The observed rate of cytogenetic disturbances was comparable with the effect of the maximum studied level or the radioactive soil pollution. The heaviest damage to aberrant cells was found in the presence of 137Cs.     

Eukaryotic elongation factor 1A interacts with the upstream pseudoknot domain in the 3' untranslated region of tobacco mosaic virus RNA

The genomic RNA of tobacco mosaic virus (TMV), like that of other positive-strand RNA viruses, acts as a template for both translation and replication. The highly structured 3' untranslated region (UTR) of TMV RNAs plays an important role in both processes; it is not polyadenylated but ends with a tRNA-like structure (TLS) preceded by a conserved upstream pseudoknot domain (UPD). The TLS of tobamoviral RNAs can be specifically aminoacylated and, in this state, can interact with eukaryotic elongation factor 1A (eEF1A)/GTP with high affinity. Using a UV cross-linking assay, we detected another specific binding site for eEF1A/GTP, within the UPDs of TMV and crucifer-infecting tobamovirus (crTMV), that does not require aminoacylation. A mutational analysis revealed that UPD pseudoknot conformation and some conserved primary sequence elements are required for this interaction. Its possible role in the regulation of tobamovirus gene expression and replication is discussed.     

New data on the range,biology, and abundance of skilfish Erilepis zonifer (Anoplopomatidae)

Data on the occurrence, spatial-bathymetric distribution, and size composition of skilfish Erilepis zonifer are given on the basis of the materials collected at the long-line catches on the Emperor Ridge seamounts. This fish is a large representative of fam. Anoplopomatidae (maximal length 188 cm; weight 88.5 kg). From June to July 2009, the species was found on all five sampled underwater mountains (Nintoku, Jingu, Ojin, Koko, Northern Koko). The fish was found within the depth range 370–1040 m. The initial biomass of skilfish at the studied seamounts calculated by the Leslie method is approximately 203.5 tons. The structure of the range and possible ways of the dispersion of this species in the waters of the continental slope of the North-Pacific rim are discussed.     

NPIDB: a database of nucleic acids-protein interactions

The database NPIDB (Nucleic Acids-Protein Interaction DataBase) contains information derived from structures of DNA-protein and RNA-protein complexes extracted from PDB (1834 complexes in July 2007). It is organized as a collection of files in PDB format and is equipped with a web-interface and a set of tools for extracting biologically meaningful characteristics of complexes. The content of the database is weekly updated. AVAILABILITY: http://monkey.belozersky.msu.ru/NPIDB/     

Activated leukemic oncogenes <Emphasis Type="Italic">AML1-ETO</Emphasis> and <Emphasis Type="Italic">c-kit</Emphasis>: Role in development of acute myeloid leukemia and current approaches for their inhibition

Acute myeloid leukemia (AML) is a malignant blood disease caused by different mutations that enhance the pro-liferative activity and survival of blood cells and affect their differentiation and apoptosis. The most frequent disorders in AML are translocations between chromosomes 21 and 8 leading to production of a chimeric oncogene, AML1-ETO, and hyperexpression of the receptor tyrosine kinase KIT. Mutations in these genes often occur jointly. The presence in cells of two activated oncogenes is likely to trigger their malignization. The current approaches for treatment of oncologic diseases (bone marrow transplantation, radiotherapy, and chemotherapy) have significant shortcomings, and thus many laboratories are intensively developing new approaches against leukemias. Inhibiting expression of activated leukemic oncogenes based on the principle of RNA interference seems to be a promising approach in this field.