Api88 Is a novel antibacterial designer peptide to treat systemic infections with multidrug-resistant Gram-negative pathogens

Patricia Czihal, Daniel Knappe, Stefanie Fritsche, Michael Zahn, Nicole Berthold, Stefania Piantavigna, Uwe Müller, Sylvia Van Dorpe, Nicole Herth, Annegret Binas, Gabriele Köhler, Bart De Spiegeleer, Lisandra L. Martin, Oliver Nolte, Norbert Sträter, Gottfried Alber, Ralf Hoffmann*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The emergence of multiple-drug-resistant (MDR) bacterial pathogens in hospitals (nosocomial infections) presents a global threat of growing importance, especially for Gram-negative bacteria with extended spectrum β-lactamase (ESBL) or the novel New Delhi metallo-β-lactamase 1 (NDM-1) resistance. Starting from the antibacterial peptide apidaecin 1b, we have optimized the sequence to treat systemic infections with the most threatening human pathogens, such as Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii. The lead compound Api88 enters bacteria without lytic effects at the membrane and inhibits chaperone DnaK at the substrate binding domain with a KD of 5 μmol/L. The Api88-DnaK crystal structure revealed that Api88 binds with a seven residue long sequence (PVYIPRP), in two different modes. Mice did not show any sign of toxicity when Api88 was injected four times intraperitoneally at a dose of 40 mg/kg body weight (BW) within 24 h, whereas three injections of 1.25 mg/kg BW and 5 mg/kg BW were sufficient to rescue all animals in lethal sepsis models using pathogenic E. coli strains ATCC 25922 and Neumann, respectively. Radioactive labeling showed that Api88 enters all organs investigated including the brain and is cleared through both the liver and kidneys at similar rates. In conclusion, Api88 is a novel, highly promising, 18-residue peptide lead compound with favorable in vitro and in vivo properties including a promising safety margin.
Original languageEnglish
Pages (from-to)1281-1291
Number of pages11
JournalACS Chemical Biology
Issue number7
Early online date17 May 2012
Publication statusPublished - 20 Jul 2012


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