title: Branched Peptide, B2088, Disrupts the Supramolecular Organization of Lipopolysaccharides and Sensitizes the Gram-negative Bacteria.
abstract: Dissecting the complexities of branched peptide-lipopolysaccharides (LPS) interactions provide rationale for the development of non-cytotoxic antibiotic adjuvants. Using various biophysical methods, we show that the branched peptide, B2088, binds to lipid A and disrupts the supramolecular organization of LPS. The disruption of outer membrane in an intact bacterium was demonstrated by fluorescence spectroscopy and checkerboard assays, the latter confirming strong to moderate synergism between B2088 and various classes of antibiotics. The potency of synergistic combinations of B2088 and antibiotics was further established by time-kill kinetics, mammalian cell culture infections model and in vivo model of bacterial keratitis. Importantly, B2088 did not show any cytotoxicity to corneal epithelial cells for at least 96 h continuous exposure or hemolytic activity even at 20 mg/ml. Peptide congeners containing norvaline, phenylalanine and tyrosine (instead of valine in B2088) displayed better synergism compared to other substitutions. We propose that high affinity and subsequent disruption of the supramolecular assembly of LPS by the branched peptides are vital for the development of non-cytotoxic antibiotic adjuvants that can enhance the accessibility of conventional antibiotics to the intracellular targets, decrease the antibiotic consumption and holds promise in averting antibiotic resistance.
authors.affiliation: Singapore Eye Research Institute, Ocular Chemistry and Anti-Infectives, Singapore.|Duke-NUS Graduate Medical School, Ophthalmology and Visual Sciences Academic Clinical Program, Singapore.
authors.forename: Rajamani
authors.initials: R
authors.lastname: Lakshminarayanan
authors.affiliation: National University of Singapore, Department of Pharmacy, Singapore.
authors.forename: Wei Xiang
authors.initials: WX
authors.lastname: Tan
authors.affiliation: Singapore Eye Research Institute, Ocular Chemistry and Anti-Infectives, Singapore.
authors.forename: Thet Tun
authors.initials: TT
authors.lastname: Aung
authors.affiliation: Singapore Eye Research Institute, Ocular Chemistry and Anti-Infectives, Singapore.
authors.forename: Eunice Tze Leng
authors.initials: ET
authors.lastname: Goh
authors.affiliation: Singapore Eye Research Institute, Ocular Chemistry and Anti-Infectives, Singapore.
authors.forename: Nandhakumar
authors.initials: N
authors.lastname: Muruganantham
authors.affiliation: Singapore Eye Research Institute, Ocular Chemistry and Anti-Infectives, Singapore.
authors.forename: Jianguo
authors.initials: J
authors.lastname: Li
authors.affiliation: Singapore Eye Research Institute, Ocular Chemistry and Anti-Infectives, Singapore.
authors.forename: Jamie Ya Ting
authors.initials: JY
authors.lastname: Chang
authors.affiliation: Duke-NUS Graduate Medical School, Program in Emerging Infectious Diseases, Singapore.
authors.forename: Neha
authors.initials: N
authors.lastname: Dikshit
authors.affiliation: Singapore Eye Research Institute, Ocular Chemistry and Anti-Infectives, Singapore.
authors.forename: Padmanabhan
authors.initials: P
authors.lastname: Saraswathi
authors.affiliation: Singapore Eye Research Institute, Ocular Chemistry and Anti-Infectives, Singapore.|Ocular Immunology and Angiogenesis Lab, Department of Veterinary Medicine &Surgery, University of Missouri, Columbia, USA.
authors.forename: Rayne Rui
authors.initials: RR
authors.lastname: Lim
authors.affiliation: National University of Singapore, Department of Pharmacy, Singapore.
authors.forename: Tse Siang
authors.initials: TS
authors.lastname: Kang
authors.affiliation: Duke-NUS Graduate Medical School, Program in Emerging Infectious Diseases, Singapore.
authors.forename: Vanniarajan
authors.initials: V
authors.lastname: Balamuralidhar
authors.affiliation: Duke-NUS Graduate Medical School, Program in Emerging Infectious Diseases, Singapore.
authors.forename: Bindu
authors.initials: B
authors.lastname: Sukumaran
authors.affiliation: Agency for Science, Technology and Research (A*STAR), Bioinformatics Institute, Singapore.|National University of Singapore, Department of Biological Sciences, Singapore.|Nanyang Technological University, School of Biological Sciences, Singapore.
authors.forename: Chandra S
authors.initials: CS
authors.lastname: Verma
authors.affiliation: National University of Singapore, Department of Biological Sciences, Singapore.
authors.forename: Jayaraman
authors.initials: J
authors.lastname: Sivaraman
authors.affiliation: Singapore Eye Research Institute, Ocular Chemistry and Anti-Infectives, Singapore.|Ocular Immunology and Angiogenesis Lab, Department of Veterinary Medicine &Surgery, University of Missouri, Columbia, USA.
authors.forename: Shyam Sunder
authors.initials: SS
authors.lastname: Chaurasia
authors.affiliation: Singapore Eye Research Institute, Ocular Chemistry and Anti-Infectives, Singapore.|Duke-NUS Graduate Medical School, Ophthalmology and Visual Sciences Academic Clinical Program, Singapore.
authors.forename: Shouping
authors.initials: S
authors.lastname: Liu
authors.affiliation: Singapore Eye Research Institute, Ocular Chemistry and Anti-Infectives, Singapore.|Duke-NUS Graduate Medical School, Ophthalmology and Visual Sciences Academic Clinical Program, Singapore.
authors.forename: Roger W
authors.initials: RW
authors.lastname: Beuerman
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D023181:Antimicrobial Cationic Peptides / Q000008:administration & dosage* / Q000494:pharmacology; D058491:Bacterial Load / Q000187:drug effects; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D006090:Gram-Negative Bacteria / Q000187:drug effects* / Q000378:metabolism; D016905:Gram-Negative Bacterial Infections / Q000188:drug therapy*; D006801:Humans; D007634:Keratitis / Q000188:drug therapy* / Q000382:microbiology; D008070:Lipopolysaccharides / Q000737:chemistry* / Q000378:metabolism; D051379:Mice; D056004:Molecular Dynamics Simulation; D013050:Spectrometry, Fluorescence
chemical_list: D000900:Anti-Bacterial Agents; D023181:Antimicrobial Cationic Peptides; C579492:B2088 peptide; D008070:Lipopolysaccharides