ИСТИНА

In view of the growing bacterial resistance, the development of new antibiotics is an urgent task. The modification of widely used antibacterials with various chemical residues is one of the main approaches for creating new compounds with improved properties. The combination in the antibiotic structure several moities that act on different active sites will allow to trick the mechanisms of bacterial resistance. Chloramphenicol is a widespread antibiotic that acts by inhibiting bacterial protein biosynthesis. Its binding site is located in the A-site of the peptidyl transferase center of the ribosome. The replacement of the dichloroacetyl residue in the chloramphenicol molecule by a peptide will expand its binding site to the ribosomal tunnel. These chimeric molecules can also be used for studying the interaction of ribosome nucleotides with the peptide attached to the antibiotic. To find the optimal amino acid sequences of the peptides, molecular docking based virtual screening of all possible tripeptide chloramphenicol analogues for their binding to the ribosome was carried out. Compounds containing peptides FWH, VFR, RAW, AAA, both with the free N-terminal amino group and the protected by acetyl group, were selected and synthesized. The affinity of the compounds to the ribosome was measured using a competitive displacement assay. It turned out that some of the analogues bind to the ribosome 30 times better than the original antibiotic, which is consistent with the virtual screening results. The use of 23S RNA chemical probing made it possible to determine the nucleotides involved in the interactions with the peptide moiety of the molecules and suggest their binding mechanism. The ability of some compounds to inhibit protein biosynthesis in vitro was comparable to that of chloramphenicol, making the obtained analogues promising for further antibacterial activity studies. This work was supported by the grants RFBR (16-04-00709) and RSF (14-24-00061-P).