Design and Computational Evaluation of a Beta-Hairpin Antimicrobial Peptide Targeting Pseudomonas aeruginosa ATCC 27853

The modern era of antibiotics began with Paul Ehrlich’s synthetic Salvarsan in 1910 and Alexander Fleming’s discovery of natural penicillin in 1928. This led to a golden age of antibiotic development and use throughout the century, revolutionizing medicine. Now, while antibiotic development has slowed, antimicrobial resistance has emerged, creating a major global health challenge and threat to efficacy in medicine. Antibiotic resistance, a natural evolutionary process, has been accelerated by human actions through agriculture and medicine. WHO now recognizes antimicrobial resistance (AMR) as one of the top 10 global public health threats. Over time, bacteria have evolved to withstand drugs designed to kill them. This crisis has been driven heavily by misuse and overuse of antibiotics, leading to infections which are far harder to treat. These bacteria develop enzymes and other mechanisms which break down or disable antibiotics, making them ineffective. As bacteria become more resistant to antibiotics, infections require stronger, more expensive, or more toxic treatments. This has increased mortality among these types of infections which cause serious illness. Pseudomonas aeruginosa ATCC 27853 is an opportunistic Gram-negative pathogen and is known to cause difficult-to-treat infections and high antibiotic resistance. They have been found to be especially problematic and common in hospitals, where they affect immunocompromised patients and are a major cause of serious infections. They are a major cause of ventilator-associated pneumonia, bloodstream infections, urinary tract infections, and chronic lung infections in cystic fibrosis patients. Their impact is exacerbated by their ability to form biofilms, communities of organisms which adhere to surfaces which protect the bacteria from antibiotics. Listed as a World Health Organization “critical priority” pathogen, their high resistance to antibiotics makes treatment even harder. This specific reference strain of P. aeruginosa is cataloged by the American Type Culture Collection (ATCC). It is used globally as a quality control strain and has a well-documented, stable, and reproducible resistance profile. Anti-microbial peptides (AMPs), molecules which serve as a part of organisms’ innate immune system to defend against microbial invaders, offer a potential solution because of key properties. AMPs are typically short (generally 10 - 50 amino acids), cationic, amphipathic, and can physically disrupt bacterial membranes instead of targeting a single biochemical pathway. This allows them to disrupt microbial cell membranes and walls, leading to cell death through various mechanisms. Due to their positive change and double-hydrophobic and hydrophilic nature, they can easily disrupt membranes. Some AMPs form channels in the membranes, leading to leakage and cell death. These molecules also utilize other mechanisms, including inhibition of intracellular processes or interference with well wall construction. β-hairpin AMPS have two antiparallel β-strands linked by a short turn. These often have cystines at the end and share essential structural features for development of new antibiotics. However, despite their structural stability and effectiveness in disrupting bacterial membranes, β-hairpin AMPS cause potential host toxicity and protease degradation. This study aims to design and computationally evaluate β-hairpin peptide variants against Pseudomonas aeruginosa ATCC 27853 using AMP prediction tools for cross-validation. We identify sequence modifications that enhance predicted potency while preserving structural stability and minimizing host toxicity. It is hypothesized that the original AMP can be enhanced through key properties such as charge, hydrophobicity, and amphipathicity.