title: Biopanning of endotoxin-specific phage displayed peptides.
abstract: Systemic bacterial infections frequently lead to a plethora of symptoms termed "endotoxic shock" or "sepsis." Characterized by hypotension, coagulation abnormalities, and multiple organ failure, treatment of sepsis still remains mostly supportive. Of the various experimental therapeutic interventional strategies, neutralization of endotoxin by peptides or proteins is becoming popular recently. Hence, design of endotoxin binding peptides is gaining currency as their structural complexity and mode of recognition of endotoxin precludes mounting of resistance against them by the susceptible bacteria by genetic recombination, mutation, etc. Earlier work from our laboratory had shown that the amphiphilic cationic peptides are good ligands for endotoxin binding. In this study, we report the results of studies with the 12 selected lipid A binding phage displayed peptides by biopanning of a repertoire of a random pentadecapeptide library displayed on the filamentous M-13 phage. A comparison of the sequences revealed no consensus sequence between the 12 selected peptides suggesting that the lipid A binding motif is not sequence specific which is in accord with the sequence variation seen with the naturally occurring anti-microbial and/or endotoxin binding peptides. Thus, the flexibility of the peptides coupled with their plasticity in recognizing the lipid A moiety, explains their tight binding to endotoxin. At a structural level, asymmetric distribution of the charged polar residues on one face of the helix and non-polar residues on the opposite face appears to correlate with their activity.
authors.affiliation: Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, India.
authors.forename: Celestine J
authors.initials: CJ
authors.lastname: Thomas
authors.forename: Shilpi
authors.initials: S
authors.lastname: Sharma
authors.forename: Gyanendra
authors.initials: G
authors.lastname: Kumar
authors.forename: Sandhya S
authors.initials: SS
authors.lastname: Visweswariah
authors.forename: Avadhesha
authors.initials: A
authors.lastname: Surolia
mesh_terms: D000595:Amino Acid Sequence; D017104:Bacteriophage M13 / Q000235:genetics / Q000378:metabolism; D002021:Buffers; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008050:Lipid A / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D019151:Peptide Library; D010455:Peptides / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017433:Protein Structure, Secondary; D020349:Surface Plasmon Resonance
chemical_list: D002021:Buffers; D008050:Lipid A; D019151:Peptide Library; D010455:Peptides