[Photoaffinity modification of Escherichia coli ribosomes by fMet-tRNAf Met derivatives in the 70S initiation complex]. / Issledovanie fotoaffinnoi modifikatsii ribosom Escherichia coli proizvodnymi fMet-tRNKf Met v sostave 70S kompleksa initsiatsii.

Photoaffinity labeling of E. coli ribosomes within the 70S initiation complex was studied by using photoreactive derivatives of fMet-tRNAfMet bearing arylazidogroups scattered statistically over guanosine residues. It is shown that fMet-azido-tRNAfMet-II bearing 2 moles of the reagent residues per mole of tRNA (modified in the conditions of stability of tRNA tertiary structure) is fully active in aminoacylation and in the factor-dependent binding with ribosomes to form the 70S initiation complex. Functional activity of fMet-azido-tRNAfMet-I bearing also 2 moles of the reagent residues per mole of tRNA (but modified in conditions of lability of tRNA tertiary structure) decreases up to approximately 45% in aminoacylation and up to 70% in IF-2 X GTP-dependent binding to the ribosomes. Irradiation of complexes 70S ribosome-MS2-RNA-fMet-azido-tRNAfMet results in covalent linking of the tRNA derivative to the ribosomes. Both subunits are labeled, the 30S to a larger extent than 50S. It is shown that fMet-azido-tRNAfMet-II labels proteins S1, S7, S9, L27 whereas fMet-azido-tRNAfMet-1--proteins S1, S3, S5, S9, S14, L1, L2, L7/L12.

[Study of the ribosome mRNA-binding region during different stages of translation. I. Functional activity of mRNA analogs, AUGU6 and its benzylidene derivatives, in ribosome-dependent protein synthesis]. / Issledovanie mRNK-sviazyvaiushchei oblasti ribosomy na raznykh étapakh transliatsii. I. Funktsional'naia aktivnost' analogov mRNK--AUGU6 i ego benzilidenovykh proizvodnykh--v ribosomnozavisimom belkovom sinteze.

Hexaribouridylic acid, prepared by digestion of poly(U) with cobra venom endonuclease, and trinucleotide AUG synthesized chemically by triester approach were joined by RNA-ligase to yield a nonaribonucleotide AUGU6 bearing the initiation codon at its 5'-terminus. 2',3'-O-(4-[N-(2-chloro(or hydroxy) ethyl-N-Methylamino])- benzylidene residues were introduced at the 3'-terminus of oligonucleotide AUGU6 and its benzylidene derivatives AUGU6CHRCl or AUGU6CHROH were obtained. The mRNA analogs synthesized were tested for their template activity in the formation of 70S initiation complex. AUGU6, AUGU6CHRC1 and AUGU6CHROH were shown to stimulate factor-dependent binding of fMet-tRNA to ribosomes. The effect of benzylidene fragment on the template activity of AUGU6CHROH in the course of translation process was studied. It was shown that AUGU6CHROH stimulates synthesis of di- and tripeptides with the same efficiency as AUGU6.

[Regulatory region of fr phage replicase cistron. II. Isolation and structure of specific fr RNA fragments]. / Reguliatornyi uchastok tsistrona replikazy faga fr. II. Vydelenie i struktura spetsificheskikh fragmentov RNK fr.

A new set of short RNA templates has been prepared for functional studies in initiation of translation in vitro. Number of individual RNA fragments which contain complete or part of the initiatory region of phage fr replicase cistron were isolated from complex fr RNA--fr coat protein. Their primary structure were determined by using standard fingerprint technique and rapid gel sequencing. Secondary structure of several RNA fragments and their binding activity with phage fr and MS2 coat proteins has been also studied.

[Preparation of RNAase-free E. coli ribosomes active in initiation of protein biosynthesis]. / Vydelenie aktivnykh v initsiatsii biosinteza belka ribosom E. coli, svobodnykh ot primesei RNKaz.

The level of contaminating RNAases in the main components of the protein biosynthesis initiation system, the initiation factors and ribosomes of E. coli, was studied. It was shown that the ribosomes are the major source of contaminating RNAases. A simple procedure for purification of ribosomes active in initiation including Sephadex G-200 gel-filtration of unwashed ribosomes in a 1.5 M NH4Cl-containing buffer was developed.