Conjugation with polyamines enhances the antibacterial and anticancer activity of chloramphenicol

Ourania N Kostopoulou,Maria Rodi,Dionissios Papaioannou,Dimitrios L Kalpaxis,Thomas Garnelis,Georgios Papadopoulos,Ioannis Panagoulias,Athanasia Mouzaki,George E Magoulas,Ekaterini C Kouvela,George P Dinos

doi:10.1093/nar/gku539

Ourania N Kostopoulou, Maria Rodi + Show 9 more

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https://doi.org/10.1093/nar/gku539

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Abstract

Chloramphenicol (CAM) is a broad-spectrum antibiotic, limited to occasional only use in developed countries because of its potential toxicity. To explore the influence of polyamines on the uptake and activity of CAM into cells, a series of polyamine–CAM conjugates were synthesized. Both polyamine architecture and the position of CAM-scaffold substitution were crucial in augmenting the antibacterial and anticancer potency of the synthesized conjugates. Compounds 4 and 5, prepared by replacement of dichloro-acetyl group of CAM with succinic acid attached to N4 and N1 positions of N8,N8-dibenzylspermidine, respectively, exhibited higher activity than CAM in inhibiting the puromycin reaction in a bacterial cell-free system. Kinetic and footprinting analysis revealed that whereas the CAM-scaffold preserved its role in competing with the binding of aminoacyl-tRNA 3′-terminus to ribosomal A-site, the polyamine-tail could interfere with the rotatory motion of aminoacyl-tRNA 3′-terminus toward the P-site. Compared to CAM, compounds 4 and 5 exhibited comparable or improved antibacterial activity, particularly against CAM-resistant strains. Compound 4 also possessed enhanced toxicity against human cancer cells, and lower toxicity against healthy human cells. Thus, the designed conjugates proved to be suitable tools in investigating the ribosomal catalytic center plasticity and some of them exhibited greater efficacy than CAM itself.

Highlights

The ribosome is an extremely complex cellular organelle that provides the platform upon which the codons of the mRNA are decoded by aminoacyl-tRNAs
We re-examined the dynamic behavior of the ribosome, using a series of polyamine (PA)–chloramphenicol (CAM) conjugates to probe the peptidyl transferase (PTase) region plasticity, and applying kinetic analysis combined with time-resolved footprinting analysis to map the interactions between ribosomal RNA (rRNA) and these novel agents
We examined the inhibition of peptide bond formation by a series of PA–CAM conjugates

Summary

Introduction

The ribosome is an extremely complex cellular organelle that provides the platform upon which the codons of the mRNA are decoded by aminoacyl-tRNAs. During the successive stages of protein synthesis, the ribosome can interact with a diverse set of additional ligands, like translation factors and antibiotics, which coordinate the function and structure of different regions of the translational machinery to assume the appropriate conformational states which ensure the prospective response. Other approaches have been used to dissect more efficiently the dynamic character of the translation process and the plasticity of ribosomal structure, such as kinetics [4], timeresolved footprinting analysis [5], cryo-electron microscopy [6], NMR analysis [7], FRET-based approaches [8], molecular dynamics modeling [9] and biochemical techniques combined with molecular genetics [10]. We re-examined the dynamic behavior of the ribosome, using a series of polyamine (PA)–chloramphenicol (CAM) conjugates to probe the peptidyl transferase (PTase) region plasticity, and applying kinetic analysis combined with time-resolved footprinting analysis to map the interactions between rRNA and these novel agents

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Conclusion