Discovery and Development of Cyclic Peptide Inhibitors of CIB1.

Calcium and integrin binding protein 1 (CIB1) is a small, intracellular protein recently implicated in survival and proliferation of triple-negative breast cancer (TNBC). Considering its interactions with PAK1 and downstream signaling, CIB1 has been suggested as a potential therapeutic target in TNBC. As such, CIB1 has been the focus of inhibitor discovery efforts.

Exploring the Post-translational Enzymology of PaaA by mRNA Display.

PaaA is a RiPP enzyme that catalyzes the transformation of two glutamic acid residues within a substrate peptide into the bicyclic core of Pantocin A. Here, for the first time, we use mRNA display techniques to understand RiPP enzyme-substrate interactions to illuminate PaaA substrate recognition. Additionally, our data revealed insights into the enzymatic timing of glutamic acid modification.

Flexizyme-Enabled Benchtop Biosynthesis of Thiopeptides.

Thiopeptides are natural antibiotics that are fashioned from short peptides by multiple layers of post-translational modification. Their biosynthesis, in particular the pyridine synthases that form the macrocyclic antibiotic core, has attracted intensive research but is complicated by the challenges of reconstituting multiple-pathway enzymes. By combining select RiPP enzymes with cell free expression and flexizyme-based codon reprogramming, we have developed a benchtop biosynthesis of thiopeptide scaffolds.