Overview of research
Designing improved antifungal peptides
Antimicrobial peptides are short peptides that inhibit the growth of microorganisms, including bacteria and fungi. While the effect of antimicrobial peptides on cells is their most important characteristic, the stability of the peptides in their environment is also important to understand for developing peptides with therapeutic potential. We are studying the proteolytic stability of peptides with activity against the most common fungal pathogen, Candida albicans. One peptide we study is the human salivary antifungal peptide histatin 5. Histatin 5 has potent antifungal activity against C. albicans, but the fungus produces secreted aspartic proteases (Saps) that can degrade the peptide and make it inactive. We are designing modified peptides with reduced reduced cleavage by the Saps and improved antifungal activity.
Engineering cell-penetrating peptides to target fungal pathogens
Cell-penetrating peptides (CPPs) are short, structurally diverse peptides with the ability to cross cell membranes. While translocating into cells, they can carry a variety of bioactive cargo, including nucleic acids, proteins, and nanoparticles. CPPs have been widely studied in mammalian cells, but knowledge of their interactions with fungal cells are much more limited. We use biological experiments, biophysical experiments, and molecular simulations to study how the structure of CPPs affects their ability to translocate into Candida pathogens and their specificity for fungal cells versus mammalian cells. We are also studying how the properties of the molecular cargo carried by the CPPs affects translocation.
Immobilizing antibodies for diagnostic applications
Antibodies are highly specific molecules with important applications in disease diagnostics. Creating arrays with large numbers of antibodies on a surface will increase the number of diseases that can be detected and the accuracy of the detection, but immobilizing many different antibodies on a surface can be challenging. To efficiently immobilize antibodies, we biotinylate the antibodies in vivo during recombinant expression in Escherichia coli cells and immobilize them onto a streptavidin-coated surface directly from cell lysate. We are studying how the properties of the immobilized construct (antibody, biotinylation tag, linker sequence) affect immobilization and antibody functionality, while also exploring how our antibody arrays can be used to detect clinically relevant targets.
Engineering intracellular antibodies
Intracellular antibodies ("intrabodies") are antibodies that bind to a target molecule inside cells. They must be engineered to fold in the reducing intracellular environment without the disulfide bonds normally required for proper folding. Although intrabodies have promise in therapeutics and research, the ability to efficiently engineer them to bind a target in the intracellular environment has limited their use. We developed and use an intrabody engineering method that takes advantage of an intracellular folding quality control mechanism in Escherichia coli to efficiently engineer intrabodies for proper intracellular folding and for binding to a target protein. We are using our screening method to engineer antibodies and other binding scaffolds with high affinity for targets that have biomedical relevance, with a particular interest in targeting proteins important in cancer.