Quorum sensing (QS) is a cell–cell communication mechanism that enables bacteria to assess their population density and alter their behavior upon reaching high cell number. Many bacterial pathogens utilize QS to initiate an attack on their host, thus QS has attracted significant attention as a potential antivirulence alternative to traditional antibiotics. Streptococcus pneumoniae, a notorious human pathogen responsible for a variety of acute and chronic infections, utilizes the competence regulon and its associated signaling peptide, the competence stimulating peptide (CSP), to acquire antibiotic resistance and establish an infection. In this work, we sought to define the binding pockets within the ComD1 receptor used for binding the hydrophobic side-chain residues in CSP1 through the introduction of highly-conservative point mutations within the peptide. Optimization of these binding interactions could lead to the development of highly potent CSP-based QS modulators while the inclusion of non-natural amino acids within the CSP sequence would confer resistance to protease degradation, a requirement for drug candidates.

Anomalous protein-protein interactions (PPIs) have been correlated to a variety of disease states, such as cancer, infectious disease, neurological disorders, diabetes, endocrine disorders and cardiovascular disease. Stapled peptides are an emerging intervention for these PPIs due to their improved structural rigidity and pharmacokinetic properties relative to unstapled peptides. This review details the most recent advances in the field of stapled peptide therapeutics, including the increasing variety of PPIs being targeted and types of peptide staples being employed.