The aim of the collaborative research project is to unravel the structure function relationships of lantibiotics and the development of lantibiotics with improved properties with respect to the solubility and bactericidal activity. The development of molecules with relaxed bactericidal activity is also anticipated.
The goal of the project was the understanding of the interrelations between biosynthesis, producer immunity, structure and function as a basis for the rational design of new lantibiotics.
The research is proceeding with few problems. Accomplishments to date include:
isolation of 7 novel lantibiotics;
detection of the first lantibiotic immunity gene;
isolation of Pep5 prepeptides in all stages of modification that had been postulated;
identification of a natural nisin variant (nisin Z);
overproduction of nisin Lactococcus lactis strains;
first protein engineering of nisin resulting in various mutants with altered structure and activity;
sequencing of genes of nisin operon;
synthesis and conformational characterization of all known leader peptides of prelantibodics;
3-dimensional structure determinations of nisin and Pep5.
Lantibiotics are a recently defined family of post translationally modified peptide antibiotics that possess bactericidal activity against a wide variety of Gram-positive bacteria and their spores. They are produced by Gram-positive bacteria of different genera and are characterized by a high content of unusual aminoacids especially, lanthionine, thioether-bridged aminoacids and 2,3-dihydro aminoacids. The lantibiotics exhibit extremely low toxicity. The best studied lantibiotic, nisin, produced by lactic acid bacteria, occurs naturally in dairy products and is used as a preservative in the food industry. It is anticipated that other lantibiotics will find their use as a medicine against bacterial and viral infections or as regulator of blood pressure.
Lantibiotics are synthesized on the ribosome and post translationally processed and modified. Although the chemical structures of some lantibiotics are available knowledge of the mechanism of their biosynthesis and post translational modification is very limited. Several hypothesis have been put forward for their mechanism of action including an effect on the potential of the bacterial membrane by pore formation, but nothing is known about their structure function relationships.
In the project four different research groups, with complementary know how, expertise and laboratory infrastructure, are collaborating in an effort to unravel the structure function relationships of lantibiotics and to describe and develope a second generation of these molecules. To this end, modified and mutant lantibiotics will be constructed, isolated and synthesized. Moreover, new lantibiotics will be isolated from other natural sources. The relationship between structure and function (or activity) will be investigated through elucidation of the 3-dimensional structure of wildtype and mutant lantibiotics with the aid of NMR spectroscopy combined with studies of the processess involved in bacteriocine biosynthesis, post translational processing, modification and secretion, and of the mechanism responsible for cell killing and immunity.
Funding SchemeCSC - Cost-sharing contracts
6710 BA Ede