title: C-Terminal Modification and Multimerization Increase the Efficacy of a Proline-Rich Antimicrobial Peptide.
abstract: Two series of branched tetramers of the proline-rich antimicrobial peptide (PrAMP), Chex1-Arg20, were prepared to improve antibacterial selectivity and potency against a panel of Gram-negative nosocomial pathogens including Escherichia coli, Klebsiella pneumoniae, Acinetobacter baumannii and Pseudomonas aeruginosa. First, tetramerization was achieved by dithiomaleimide (DTM) conjugation of two C-terminal-cysteine bearing dimers that also incorporated C-terminal peptide chemical modification. DTM-linked tetrameric peptides containing a C-terminal hydrazide moiety on each dimer exhibited highly potent activities in the minimum inhibitory concentration (MIC) range of 0.49-2.33 μm. A second series of tetrameric analogues with C-terminal hydrazide modification was prepared by using alternative conjugation linkers including trans-1,4-dibromo-2-butene, α,α'-dibromo-p-xylene, or 6-bismaleimidohexane to determine the effect of length on activity. Each displayed potent and broadened activity against Gram-negative nosocomial pathogens, particularly the butene-linked tetrameric hydrazide. Remarkably, the greatest MIC activity is against P. aeruginosa (0.77 μm/8 μg mL-1) where the monomer is inactive. None of these peptides showed any cytotoxicity to mammalian cells up to 25 times the MIC. A diffusion NMR study of the tetrameric hydrazides showed that the more active antibacterial analogues were those with a more compact structure having smaller hydrodynamic radii. The results show that C-terminal PrAMP hydrazidation together with its rational tetramerization is an effective means for increasing both diversity and potency of PrAMP action.
authors.affiliation: The Florey Institute of Neuroscience and Mental Health, University of Melbourne, VIC, 3010, Australia.|School of Chemistry, University of Melbourne, VIC, 3010, Australia.
authors.forename: Wenyi
authors.identifier: 0000-0003-3584-0301
authors.initials: W
authors.lastname: Li
authors.affiliation: Oral Health CRC, Melbourne Dental School, University of Melbourne, VIC, 3010, Australia.|Bio21 Institute, University of Melbourne, VIC, 3010, Australia.
authors.forename: Neil M
authors.identifier: 0000-0001-8462-5603
authors.initials: NM
authors.lastname: O'Brien-Simpson
authors.affiliation: Bio21 Institute, University of Melbourne, VIC, 3010, Australia.
authors.forename: Shenggen
authors.initials: S
authors.lastname: Yao
authors.affiliation: The Florey Institute of Neuroscience and Mental Health, University of Melbourne, VIC, 3010, Australia.
authors.forename: Julien
authors.identifier: 0000-0003-0391-2526
authors.initials: J
authors.lastname: Tailhades
authors.affiliation: Oral Health CRC, Melbourne Dental School, University of Melbourne, VIC, 3010, Australia.|Bio21 Institute, University of Melbourne, VIC, 3010, Australia.
authors.forename: Eric C
authors.identifier: 0000-0002-6618-4856
authors.initials: EC
authors.lastname: Reynolds
authors.affiliation: Land Division, Defence Science and Technology Group, Fishermans Bend, VIC, 3207, Australia.
authors.forename: Raymond M
authors.initials: RM
authors.lastname: Dawson
authors.affiliation: Department of Biology, Temple University, Philadelphia, PA, 19122, USA.
authors.forename: Laszlo
authors.initials: L
authors.lastname: Otvos
authors.affiliation: The Florey Institute of Neuroscience and Mental Health, University of Melbourne, VIC, 3010, Australia.|School of Chemistry, University of Melbourne, VIC, 3010, Australia.
authors.forename: Mohammed Akhter
authors.identifier: 0000-0002-9961-0006
authors.initials: MA
authors.lastname: Hossain
authors.affiliation: School of Chemistry, University of Melbourne, VIC, 3010, Australia.|Bio21 Institute, University of Melbourne, VIC, 3010, Australia.
authors.forename: Frances
authors.identifier: 0000-0002-6484-2763
authors.initials: F
authors.lastname: Separovic
authors.affiliation: The Florey Institute of Neuroscience and Mental Health, University of Melbourne, VIC, 3010, Australia.|School of Chemistry, University of Melbourne, VIC, 3010, Australia.
authors.forename: John D
authors.identifier: 0000-0002-1352-6568
authors.initials: JD
authors.lastname: Wade
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000737:chemistry* / Q000494:pharmacology / Q000633:toxicity; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry* / Q000494:pharmacology / Q000633:toxicity; D002460:Cell Line; D003428:Cross Infection / Q000382:microbiology; D006090:Gram-Negative Bacteria / Q000187:drug effects; D006801:Humans; D006842:Hydrocarbons, Brominated / Q000737:chemistry; D008301:Maleimides / Q000737:chemistry; D055232:Proline-Rich Protein Domains; D055503:Protein Multimerization; D051381:Rats
chemical_list: C000625049:2,3-dibromomaleimide; D000900:Anti-Bacterial Agents; D023181:Antimicrobial Cationic Peptides; D006842:Hydrocarbons, Brominated; D008301:Maleimides; C525695:alpha,alpha'-dibromoxylene; C000625050:trans-1,4-dibromo-2-butene; C075594:1,6-bismaleimidohexane
keywords: compacted structure; conjugation; expanded activity; peptides; tetramers