An engineered multidomain bactericidal peptide as a model for targeted antibiotics against specific bacteria

Abstract

We constructed a peptide consisting of a staphylococcal AgrD1 pheromone fused to the channel-forming domain of colicin Ia and named it pheromonicin. This fusion peptide had bactericidal effects against methicillin-sensitive and methicillin-resistant Staphylococcus aureus (MSSA and MRSA, respectively), but not against Staphylococcus epidermidis or Streptococcus pneumoniae. Growth rates, vital staining and colony forming unit (CFU) counts showed that pheromonicin did not merely suppress growth but killed S. aureus cells. The specificity of pheromonicin was shown by the absence of bactericidal effects against an accessory gene regulator (agr) locus knockout of S. aureus, and a dose-dependent inhibition of the bactericidal effects of pheromonicin by competition with corresponding free AgrD pheromone. In vivo, all pheromonicin-treated mice survived administration of MRSA that was lethal to controls. No toxicity was detectable in human liver or renal cells in culture, or in livers, kidneys or spleens of pheromonicin-treated mice. The results suggest that these types of chimeric peptides may be of value as antibiotics against specific bacterial infections.

A Novel Target-Specific, Salt-Resistant Antimicrobial Peptide against the Cariogenic Pathogen Streptococcus mutans

“…To circumvent this problem, an innovative approach has recently been developed to design a new class of antimicrobials, called "specifically targeted antimicrobial peptides" (STAMPs), which selectively target a specific organism with little effect on the other members of the resident flora (7,10,26). The design of such target-specific AMPs requires the identification of two functionally independent peptide components, a killing moiety comprised of a nonspecific AMP that can rapidly kill bacterial cells and a targeting moiety consisting of an organism-specific, high-affinity binding peptide (7,26). The two moieties are then joined via a small linker to generate a fusion AMP without detrimental changes in their independent activities.…”

“…The two moieties are then joined via a small linker to generate a fusion AMP without detrimental changes in their independent activities. The major advantage of such an AMP is that the targeting moiety can guide the fusion peptide to bind selectively to the target organism, allowing peptide-guided killing (7,26). It is also desirable that such a fusion peptide should be relatively stable and retain its bactericidal activity under a range of physiological conditions, such as different salt concentrations, ionic strengths, pHs, and other factors in body fluids (8,15,34).…”

“…To determine the killing kinetics and selectivity of the fusion peptides, we performed time-kill experiments against S. mutans strains, S. sanguinis SK108, and S. gordonii DL1 in both single-and dual-species cultures using methods described previously (19,23,26). Briefly, mid-log-phase cultures of these strains were first adjusted to the same cell density at OD 590 .…”

A Novel Engineered Peptide, a Narrow-Spectrum Antibiotic, is Effective against Vancomycin-Resistant Enterococcus faecalis

“…Exposure of S. aureus cells to PMC-SA, a control chimeric protein containing pheromone from S. aureus, caused an 80% growth inhibition (Fig. 2e) (14). Withdrawal of PMC-EF failed to restore growth (data not shown).…”

“…This is true for Enterococcus faecium and to a lesser extent for Enterococcus faecalis, which have developed resistance to many antibiotics, including vancomycin (12,16). We have shown that a staphylococcal pheromone fused to a channel-forming peptide killed staphylococci in culture and animal infections (14). Here, we report on an application of that strategy to vancomycin-resistant E. faecalis (VRE) strains.…”