A new class of antibiotics inhibiting bacterial trans-translation – antibio

Synthesis of of KKL- 35 analogues - medicinal chemistry program
- Synthesis and characterization of the activity of antimicrobial peptides
- Development of high-throughput detection system of trans- translation, with red and green fluorescent reporters in vivo
- Testing of compounds toxicity on eukaryotic cells
- Characterization of the activity and mechanisms of action of new anti- bacterial molecules on reference strains and a panel of hospital strains .

To date 35 original molecules were synthesized and purified. The biological activity of each molecule was assessed in vitro and in vivo. A new fluorimetric Red / Green reporter system measuring trans- translation and in vivo protease activity was developed .

The first data show clearly that :
- The series of molecules derived from KKL- 35 are strongly active on cell proteases and less on trans- translation .
- Toxicity is low or even absent at the concentrations tested for the molecule CT1-83
- Four new molecules CT1-83 ; CT1-115 ; CT1-69 and CT1-109 display a strong antibacterialactivity that is higher than the KKL- 35 reference molecule on many Gram + strains and Gram -

Our study will now focus on these four molecules to improve their activity and potentiate their synergistic protease inhibitor / anti -trans- translation effects. We will also continue mechanistic studies to accurately identify their molecular targets

Ongoing patent : red/green reporter system

Publications quoting this ANR:
Quality control in protein synthesis.
Gillet R.
Biochimie. 2015 Jul;114:1

[Protein synthesis by the ribosome: a pathway full of pitfalls].
Macé K, Giudice E, Gillet R.
Med Sci (Paris). 2015 Mar;31(3):282-90

Ongoing :
1) A new performing reporter system to detect trans-translation in vivo
2) New derivatives of KKL35 with broad-spectrum antibiotic activity.
3) Structure of an elongation factor G-ribosome complex captured in the absence of any inhibitor

Antibiotics are molecules that attack bacteria by blocking their growth (bacteriostatic affect) or by destroying them (bactericidal effect). Their introduction in civil and military therapies began during the Second World War, with the discovery and production of penicillin, which saved thousands of wounded soldiers. Then industrial methods of production of penicillin and other antibiotics allowed the treatment of many life-threatening bacterial diseases such as tuberculosis, pneumonia, syphilis, tetanus. Yet the intensive use of antibiotics quickly introduced a selection pressure leading today to an increased population of antibiotic-resistant microorganisms and an overall decrease in therapeutic efficacy. The emergence of resistant strains is characterized by north vs south and industrial vs developing countries gradients. So this problem is particularly important during military operations, when soldiers come into contact with these germs in developing countries and countries in the southern hemisphere. In a same way, the french military hospitals are also affected by the resurgence of many nosocomial infections, close to those found in public hospitals. The four most common bacteria isolated in the french military hospitals are Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli and Enterococcus. Finally, the development of a new class of broad-spectrum antibiotics should be considered as a therapeutic against major pathogens used as biological weapons, now classified as "weapons of mass destruction". Our research project focuses on the development of new broad-spectrum antibiotics targeting the primary mechanism for quality control in bacterial protein synthesis, namely trans-translation. Indeed, the translation of the genetic code into proteins by the ribosome is the corner stone of life for all cells. Considering the amount of biological data to be processed, it happens regularly that the ribosome stalls and therefore jeopardizes the survival of the cell. In bacteria, the main rescue mechanism is driven by an hybrid ribonucleic acid (RNA): the transfer-messenger RNA (tmRNA), during the process of trans-translation. Surprisingly, this system is essential to the survival of many pathogenic bacteria (Staphylococcus aureus, Mycobacterium tuberculosis, Neisseria gonorrhoeae, Helicobacter pylori, and Shigella flexneri ) and is required for virulence of other species (Salmonella, Yersinia, Francisella). Today, structural and biological data on trans-translation allow us to address this pathway as an antibiotic target particularly attractive since it is absent in eukaryotic cells. During this translational project, we will synthesize new molecules anti trans-translation; validate their activity in vitro and in vivo and finally validate their use on multiresistant bacterial strains from hospitals and representing major civil and military threats.