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>> Thesis Defense Announcement
>> To:  The George Mason University Community
>>
>> *Candidate: Nicholas Leverone
>> Program: Master of Science in Biology
>> *
>> *Date:   Tuesday April 9, 2013
>> Time:   9:30 a.m.
>> Place:  George Mason University, 
>> 	    Prince William Campus <http://www.gmu.edu/resources/welcome/Directions-to-GMU.html>
>> 	    Discovery Hall, Room 153
>> *
>>   
>> *Title: *"Small Peptide Derived from Human MMP12 CTD Is Antibacterial against Gram-negative and Gram-positive Pathogens,
>> 	 Including Multi-drug Resistant S. aureus (MRSA)*"*
>>
>> *Thesis Director*: *Dr. Monique van Hoek***
>>
>> *Thesis Committee*:  *Dr. Serguei Popov, Dr. Barney Bishop
>> *A copy of the thesis will be available in the Johnson Center 
>> Library.  All are invited to attend the defense.
>>
>> *ABSTRACT *
>> Matrix Metalloproteinase 12 (MMP12) is a macrophage produced 
>> proteolytic enzyme also known as macrophage elastase. The proteinase 
>> activity is located at its N-terminal. The C-terminal of the protein 
>> is cleaved during processing, releasing the Hemopexin-like 
>> Carboxy-terminal domain (CTD) [1-3]. The biological function of the 
>> CTD is not known. Previous work by our group demonstrated that murine 
>> MMP12 had bactericidal activity in a small peptide contained within 
>> the middle third of the CTD [4]. The goal of this study was to 
>> examine human MMP12 to determine if similar CTD-antibacterial 
>> activity could be identified. We investigated the antimicrobial 
>> properties of human MMP12 CTD with the goal of identifying potential 
>> antimicrobial peptides within this hemopexin-like protein. We tested 
>> the full-length human CTD domain for antimicrobial activity against 
>> S. aureus and other bacteria. We used three-dimensional structure 
>> analysis, comparison of known human peptides identified in blood, and 
>> bioinformatic analysis of sequences using peptide databases in order 
>> to identify strong candidates for antimicrobial activity. These 
>> candidate peptides were then synthesized and tested for antimicrobial 
>> peptide activity against S. aureus. Active peptides from this screen 
>> were further tested against other organisms, for biofilm inhibition, 
>> and for their effect on bacterial membrane integrity. The human CTD 
>> of MMP12 is antibacterial against S. aureus, P. aeruginosa, E. coli, 
>> and A. baumannii. We tested small peptides derived from CTD for 
>> antibacterial activity. Five active peptides were identified. One 
>> peptide, KY-27, displayed the lowest half-maximal effective 
>> concentration (EC50), 27.8 ÁM against S. aureus, and 47.45 ÁM against 
>> MRSA. This peptide was antimicrobial against both Gram-positive and 
>> Gram-negative bacteria, but did not inhibit biofilm formation by 
>> these organisms. When tested in an in vivo model, this peptide was 
>> able to increase survival in G. mellonella when challenged with P. 
>> aeruginosa. Our studies demonstrate that the human MMP12 CTD is 
>> antibacterial against S. aureus. We also identified a small 27 AA 
>> peptide of the CTD, KY-27, which has strong antimicrobial activity 
>> against S. aureus and multiple other pathogenic bacteria. These 
>> results suggest that KY-27 may be a vital component of the CTD 
>> bactericidal effects.
>>
>>
>>  ###
>>
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