Antimicrobial Peptides with Differential Bacterial Binding Characteristics
Final technical rept. Oct 2002-Sep 2005, Jan 2008-Dec 2010
ARMY NATICK RESEARCH AND DEVELOPMENT COMMAND MA
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This report documents research conducted by Natick Soldier Research, Development and Engineering Center NSRDEC,between 2002 and 2010, to discover, design, and assess the differential bacterial binding ability of short antimicrobial peptides AMPs as part of an effort to provide rapid, accurate, and highly sensitive detection of bacterial contamination in Soldier wounds, food, and water sources. This detection capability is pivotal to maximize Warfighter survivability and quality of life. Current biosensor platforms incorporate recognition elements, such as antibodies, that are highly selective but have limited stability and sensitivity. The current drawbacks of the biosensor have limited its usefulness for rapid, real-time detection in an operational environment. Toward development of more robust and sensitive recognition elements, a series of truncated AMPs 7-15 amino acid residues was designed using three methods 1 fragmentation of naturally-occurring AMP sequences, 2 scanning alanine mutagenesis applied to three fragments, wherein each residue in the sequence is systematically replaced with alanine to produce a set of well-defined mutations, and 3 sequence generation via a Markov chain algorithm utilizing a database of naturally-occurring AMPs. The fragmentation approach yielded multiple sequences possessing binding to all three organisms additionally, several fragments exhibited selectivity for E. coli O157H7 relative to S. aureus. Several of the fragments screened also displayed discriminatory binding to pathogenic E. coli O157H7 relative to non-pathogenic E. coli ML35. The three fragments that were further engineered via scanning alanine mutagenesis had elevated binding responses and differential binding characteristics. Sequence generation via Markov chain also yielded peptides capable of selectivity between E. coli and S. aureus.