Combining Topology and Sequence Design for the Discovery of Potent Antimicrobial Peptide Dendrimers against Multidrug‐Resistant Pseudomonas aeruginosa

Abstract

Multidrug-resistant opportunistic bacteria, such as Pseudomonas aeruginosa, represent a major public health threat. Antimicrobial peptides (AMPs) and related peptidomimetic systems offer an attractive opportunity to control these pathogens. AMP dendrimers (AMPDs) with high activity against multidrug-resistant clinical isolates of P. aeruginosa and Acinetobacter baumannii were now identified by a systematic survey of the peptide sequences within the branches of a distinct type of third-generation peptide dendrimers. Combined topology and peptide sequence design as illustrated here represents a new and general strategy to discover new antimicrobial agents to fight multidrug-resistant bacterial pathogens.

Antimicrobial Dendrimeric Peptides: Structure, Activity and New Therapeutic Applications

“…Overall, G3KL displayed a promising antibacterial activity against a large collection of difficult-to-treat isolates, including several producing carbapenemases, that are frequently faced in the contemporary international clinical scenario; in addition, the compound had little toxicity for red blood cells in vitro [25]. G3KL, which is believed to act as a membrane-disrupting compound, is a peptide dendrimer of third generation with the sequence (KL) 8 ( K KL) 4 ( K KL) 2 K KL ( K = branching lysine), structured as multiple short dipeptides connected by branching Lys residues, and has been derived through a process of sequence optimization of a hit compound spotted by screening a combinatorial library of dendrimers, by means of a custom-made high-throughput screening assay [26,27]. …”

In Vitro Activity of the Novel Antimicrobial Peptide Dendrimer G3KL against Multidrug-Resistant Acinetobacter baumannii and Pseudomonas aeruginosa

“…Several authors have modified AMPs to obtain proteolytically resistant versions, mostly by sequence variations and the use of D-amino acids (12-15). However, redesigning the peptide chain topology, in particular by introducing multiple branching points to obtain synthetic AMP dendrimers (AMPDs), seems a promising solution to overcome all of the the aforementioned problems (16-18).G3KL is a novel AMP dendrimer (AMPD) developed at the Department of Chemistry and Biochemistry of the University of Bern (Switzerland) by sequence optimization of an initial hit compound identified by screening a combinatorial library of dendrimers using a tailored high-throughput screening assay and presumed to act as a membrane-disrupting agent (19)(20)(21)(22). Its activity requires a dendritic topology and only natural lysine and leucine residues alternating in the branches (Fig.…”

“…G3KL is a novel AMP dendrimer (AMPD) developed at the Department of Chemistry and Biochemistry of the University of Bern (Switzerland) by sequence optimization of an initial hit compound identified by screening a combinatorial library of dendrimers using a tailored high-throughput screening assay and presumed to act as a membrane-disrupting agent (19)(20)(21)(22). Its activity requires a dendritic topology and only natural lysine and leucine residues alternating in the branches (Fig.…”

“…1). This novel AMPD has demonstrated in vitro activity against several Gram-negative strains, low toxicity to human red blood cells (minimal hemolytic concentration of 840 g/ml versus Ͼ2,000 g/ml for polymyxin B), stability in human serum (half-life [t 1/2 ] of ϳ18 h and MICs of 2 and 4 g/ml for P. aeruginosa PAO1 in MuellerHinton medium with or without 30% human serum, respectively), and easy preparation by standard solid-phase peptide synthesis; attempts to identify G3KL-resistant strains were also unsuccessful (21).…”

“…For G3KL, polypropylene plates were used to avoid any hypothetical attachment (and therefore effect on the MICs) of the positively charged AMPD to the surface of the polystyrene wells (21). Overall, G3KL showed MIC 50/90 values of 8/8 g/ml and MBCs at which 50% or 90% of strains tested are killed (MBC 50/90 ) of 8/8 g/ml for both A. baumannii and P. aeruginosa strains regardless of the plate used, though slightly lower MIC/MBC ranges were observed for polypropylene plates (Table 1).…”