Bacillus anthracis and other bacterial pathogens are among the more pronounced threats in the arena of bio- terrorism and biological warfare, while the occurrence of resistant strains of other gram positive pathogens (including Staphylococcus aureus, and group A Streptococcus strains) has also resulted in an urgent need for new avenues of therapeutic attack. This proposal seeks to explore the feasibility of targeting IscU, an essential protein for cellular iron metabolism and viability, as a therapeutic approach against bacterial pathogens. The proposal also builds on a novel therapeutic platform that is a focus of on-going research in this laboratory - namely, the design of catalytic drug molecules that irreversibly inactivate multiple copies of therapeutic targets. The experimental goals are to demonstrate the viability of IscU-chaperone complexes as therapeutic targets through the design and evaluation of lead drug candidates, and perform objective measures of their effectiveness in cellular assays. The proposed research will test the hypothesis that the interaction of the bacterial chaperone DnaK with the cluster assembly protein IscU can be inhibited by use of a peptide design that is based on the IscU recognition motif for chaperone DnaK. This hypothesis will be evaluated on the basis of functional assays of IscU cluster assembly and transfer reactions, and calorimetric investigations of DnaK- IscU and DnaK-peptide binding. The projected outcomes include identification of inhibitor peptides that block the function of the essential protein IscU in iron-sulfur cluster biosynthesis. Such peptides will be lead candidates for drug development. Control experiments will be carried out to evaluate the response against the equivalent human IscU and chaperone proteins. The hypothesis that candidate metallopeptides can effectively inactivate the IscU-chaperone complex in a catalytic multiturnover manner will also be tested by a similar strategy. Therapeutic candidates will be validated in cellular assays designed to demonstrate both cellular uptake and activity. Control experiments will be carried out to verify the absence of a toxic response against human cell lines.
Drug discovery remains a top priority in medical science. The phenomenon of drug resistance has heightened the need for both new classes of pharmaceutical as well as novel modes of action. In recent years we have worked to develop a distinct approach to drug design that involves both recognition and subsequent irreversible inactivation of therapeutic targets. This concept allows for improved target selectivity and lower dosage requirements and will be further developed against therapeutic targets of relevance to bio-terrorism and biological warfare, while addressing also problems arising from the occurrence of resistant strains of other gram positive pathogens (including Staphylococcus aureus, and group A Streptococcus strains).
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