Antimicrobial lasso peptide technology for producing and administering antibiotics targeting resistant Gram-negative bacterial infections

Background

The field of antibiotic development has become increasingly critical due to the rise of multidrug-resistant bacterial pathogens, particularly among Gram-negative species. One of the most challenging groups within this category is the Burkholderia cepacia complex (Bcc), which poses a severe threat to immunocompromised individuals, especially patients with cystic fibrosis (CF). These bacteria are notorious for causing chronic lung infections that are difficult to eradicate, leading to significant morbidity and mortality in affected populations. The urgent need for new therapeutic options stems from the limited efficacy of existing antibiotics and the rapid emergence of resistance mechanisms, which render standard treatments ineffective and highlight the necessity for agents with novel modes of action.

Current approaches to treating Burkholderia infections rely heavily on conventional antibiotics, such as aminoglycosides, macrolides, and fluoroquinolones, often administered in combination regimens. However, these treatments are frequently undermined by the intrinsic resistance of Burkholderia species, which possess robust efflux pumps, impermeable cell membranes, and adaptive genetic responses that neutralize antibiotic effects. Moreover, the lack of specificity and potency in available drugs can lead to suboptimal outcomes, persistent infections, and increased risk of adverse effects. The pipeline for new antibiotics targeting Gram-negative bacteria remains sparse, and few agents demonstrate both the required selectivity and safety profile for vulnerable patient populations, underscoring a significant gap in current therapeutic strategies.

Technology

Ubonodin is a novel lasso peptide antibiotic designed to combat persistent Gram-negative bacterial infections, particularly those caused by Burkholderia species, which are highly problematic in clinical settings such as cystic fibrosis care. Structurally, ubonodin consists of a 28-amino acid sequence forming a unique topology: an 8-residue isopeptide-bonded ring, an 18-residue loop, and a 2-residue tail, stabilized by steric lock residues Tyr-26 and Tyr-27. The peptide is produced using recombinant DNA technology, with the uboABCD biosynthetic gene cluster codon-optimized for efficient expression in host cells like E. coli. This allows for scalable production and purification of ubonodin and its variants, which can be formulated into pharmaceutical compositions for administration via inhalation, intravenous, or oral routes. Ubonodin acts by inhibiting bacterial RNA polymerase, providing a mechanism of action distinct from many conventional antibiotics, and can be used alone or in combination with other antimicrobial agents.

What differentiates ubonodin is its unprecedented structural features and its potent, selective activity against multidrug-resistant Burkholderia pathogens. Unlike other lasso peptides, ubonodin possesses the largest known loop and a short tail, conferring unique stability and target specificity. Its biosynthetic gene cluster is engineered for robust heterologous expression, enabling the generation of peptide variants with retained or enhanced activity. Ubonodin demonstrates strong antimicrobial effects at low micromolar concentrations against Burkholderia cepacia complex strains, while exhibiting minimal activity against unrelated bacteria, reducing off-target effects. Its stability under physiological conditions, ability to be administered through multiple routes, and compatibility with combination therapy further enhance its clinical utility. The comprehensive technical framework—including genetic constructs, production methods, and pharmaceutical formulations—positions ubonodin as a highly differentiated and promising solution for treating challenging bacterial infections where existing antibiotics often fail.

Benefits

• Potent and selective antibiotic activity against Burkholderia species, including antibiotic-resistant strains relevant to cystic fibrosis patients
• Novel mechanism of action by inhibiting bacterial RNA polymerase, reducing likelihood of cross-resistance with existing antibiotics
• Versatile administration routes including inhalation, intravenous, and oral delivery for targeted treatment
• Capability for recombinant production in heterologous hosts like E. coli, enabling scalable and controlled manufacturing
• Structural stability conferred by unique lasso peptide topology and steric lock residues, enhancing peptide durability
• Compatibility with combination therapies alongside other antimicrobial agents to improve treatment efficacy
• Detailed genetic and biochemical tools provided for peptide variant engineering and optimization

Applications

• Treatment of Burkholderia lung infections
• Antibiotic therapy for cystic fibrosis
• Combination therapy with existing antibiotics
• Recombinant peptide drug manufacturing

Additional info

Ubonodin peptides are 28-amino acid lasso peptides with 70% identity to SEQ ID NO: 1, featuring an 8-residue isopeptide-bonded ring, 18-residue loop, and 2-residue tail stabilized by Tyr-26 and Tyr-27. These molecules inhibit bacterial RNA polymerase, targeting Gram-negative *Burkholderia* pathogens. The system utilizes codon-optimized uboABCD biosynthetic gene clusters for heterologous expression and pharmaceutical compositions for treating antibiotic-resistant infections in cystic fibrosis patients.