ИСТИНА

Design and synthesis of new 3’-peptidyl-tRNA analogues, in particular “hydrolysable” analogues, which represent covalent conjugates of peptide-nucleic acid (PNA) with “stop-peptides,” were carried out. Such compounds are of interest as tools to study the ribosome functioning and as inhibitors of protein biosynthesis. (2 Aminoethyl)glycine PNA models 3’-end tRNA sequence CCA in designed structures. Computer simulations showed the formation of Watson-Crick pairing of the PNA cytosine residues with 23S rRNA nucleotides G2251 and G2252 involved in interactions with peptidyl-tRNA during its specific binding in P site of the ribosomal peptidyl transferase center (PTC). Short “stop-peptides” were planned for conjugation with PNA. These peptides form stable complexes with the ribosomal tunnel (RT) that leads to ribosome stalling and translational arrest. Structures of “hydrolysable” 3’-peptidyl-tRNA analogues that could form peptide bond with amino acid residue of aminoacyl-tRNA in A-site of PTC included 2’-deoxyriboadenosine instead of the PNA adenine containing residue. Such conjugates would permit to identify the chemical nature of specific sites localized in RT and responsible for interactions with amino acid residues of the nascent polypeptide chain. PNA and “stop-peptide” as well as PNA–“stop-peptide” conjugates were prepared by solid phase synthesis on SASRIN polymer using Fmoc/Bhoc(Boc) strategy. Synthesis of “hydrolysable” conjugates included modification of the 3’-hydroxyl of 5’-protected 2’-deoxyadenosine by N-blocked “stop-peptide”, deprotection of the 5’-hydroxyl, its conjugation with N-protected PNA and removal of protecting groups from the resulted conjugate. The binding of the new 3’-peptidyl-tRNA analogues with ribosome will be tested by chemical probing and in the cell free translation system. This study was supported by the Russian Foundation for Basic Researches (grant 10-04-01187-a).