SBIR-STTR Award

There is an immediate need for efficient, novel antifungal drugs. The fungus Aureobasidium pullulans produces a cyclic peptide know as Aureobasidin A (AbA) which is a very potent, fungicidal drug that is currently barred from commercialization due to a requirement for modifications involving complex and expensive synthetic chemistry. The overall goal of the project described in this application is to (genetically) engineer A. pullulans to produce cyclic peptides that are, or can be developed into, well-tolerated, potent, broad spectrum antifungal drugs, using no synthetic chemistry or synthetic chemistry limited to a single substitution. Phase I of the project involves the identification, cloning, sequencing and mapping of the gene encoding the non-ribosomal peptide synthetase (NRPS) complex responsible for the synthesis of native AbA in A. pullulans. Determination of the complete NRPS gene sequence will allow identification and mapping of the biosynthetic modules and domains in the complex and thereby elucidation of the assembly sequence of the native compound. This information together with the cloned gene will provide the tools required to carry out the Phase II research plan. Phase II will involve altering the native NRPS complex gene by modifying or switching the biosynthetic modules and domains thereby generating organisms capable of producing novel cyclic peptides requiring minimal chemistry to become potent broad-spectrum antifungal drugs.

Thesaurus Terms:
antifungal agent, cyclic peptide, drug design /synthesis /production, genetic manipulation antifungal antibiotic, complementary DNA, enzyme inhibitor, gene expression, genetic library, genetic mapping, molecular cloning nucleic acid sequence

There is an immediate need for novel drugs for the treatment of fungal infections, (antibiotics resistant) bacterial infections, and cancer. Cyclic peptides constitute a class of compounds that have made crucial contributions to the treatment of these diseases. Although cyclic peptides can be very efficient drugs, they are complex natural products and as such, difficult and expensive to optimize with conventional, chemistry- based methodologies. Currently used compounds are either native or native with minor modifications. Hence, the full potential of cyclic peptides for the treatment of human diseases has not been explored. The overall goal of the project is to develop a cost-effective production system for a novel antifungal drug. This molecule is a cyclic peptide and although it is both potent and well-tolerated, it requires structural modifications that cannot be introduced in a cost-effective manner by synthetic chemistry, to become a marketable product. Thus, the project involves development of methodologies and a set of genetic tools that will allow introduction of the required modifications by engineering of the non-ribosomal peptide synthetase (NRPS) complex responsible for synthesis of the molecule, in the producer organism. In Phase I, the gene encoding this NRPS complex was identified, cloned, sequenced and mapped. Phase II will involve modifying this gene such that the resulting, engineered organism will produce a drug molecule(s) with the properties required for a marketable product. Notably, successful engineering of the (NRPS gene in the) producer organism will allow production of this drug molecule at a fraction of the cost of synthetic chemistry thereby ensuring the successful commercialization of a potent, cidal antifungal drug with a novel mode of action. Successful generation of the engineered drug producer organism will: [1] provide an efficient, well-tolerated drug to a market with a strong demand for new products; [2] address a very immediate need from a growing patient population which currently have very few treatment options; and [3] provide proof of concept and critical tools for a novel and potentially very powerful genetic engineering approach to the discovery of new and improved therapeutics