Bacterial resistance to antibiotics has seriously limited our capacity to overcome infectious disease. Cases of resistance have emerged in virtually all hospital-acquired pathogen-antimicrobial combinations. Soon our most serious infectious threats will be untreatable given our dwindling arsenal of effective antibiotics. Our long-term research goals are to develop synthetic access to biologically interesting peptide antibiotics, to gain insight into their mechanism/mode of action, and to apply the knowledge gained to the development of alternative antibiotics with improved activity against resistant phenotypes. This proposal describes the total synthesis and mechanistic characterization of Ramoplanin, a novel beta-sheet lipodepsipeptide antibiotic with proven activity against methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus faecium, and cephalosporin-resistant Streptococcus pneumonia, three important Gram positive opportunistic human pathogens. By an unclear mechanism, Ramoplanin appears to arrest bacterial cell wall development at the level of MurG, a glycosyltransferase involved in an intermediate stage of peptidoglycan biosynthesis. Since MurG activity is essential for proper bacterial cell wall development, it is an attractive target for antibacterial design. Harnessing the clinical antibiotic potential of Ramoplanin critically hinges on gaining synthetic access to its structure and deconvoluting the most intimate details of its mechanism of action. To accomplish this we will synergistically merge total synthesis, mechanistic enzymology and protein biophysics to completely correlate structure to antibiotic function. We plan to synthesize Ramoplanin and related analogues using solid-phase methods, thus providing a general synthetic route to favorably modulate its physiochemical properties. We plan to identify the molecular target of Ramoplanin and determine the interaction energies, specificities, and structure of the inhibitory complex. We will assess the inhibitory effect of Ramoplanin on the MurG reaction and on the mechanistically related peptidoglycan transglycosylation cross-linking reaction that takes place on the outer surface of the bacterial cell membrane. Collectively these studies will provide a clear picture of the mechanism of Ramoplanin inhibition of peptidoglycan biosynthesis and promote the design, synthesis, and biological evaluation of a new generation of antibiotics capable of combating bacterial resistance to antibiotics.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI046611-05
Application #
6752147
Study Section
Bio-Organic and Natural Products Chemistry Study Section (BNP)
Program Officer
Peters, Kent
Project Start
2000-06-01
Project End
2006-04-14
Budget Start
2004-06-01
Budget End
2006-04-14
Support Year
5
Fiscal Year
2004
Total Cost
$309,119
Indirect Cost
Name
University of Pennsylvania
Department
Biochemistry
Type
Schools of Medicine
DUNS #
042250712
City
Philadelphia
State
PA
Country
United States
Zip Code
19104
Bellucci, Joseph J; Amiram, Miriam; Bhattacharyya, Jayanta et al. (2013) Three-in-one chromatography-free purification, tag removal, and site-specific modification of recombinant fusion proteins using sortase A and elastin-like polypeptides. Angew Chem Int Ed Engl 52:3703-8
Qi, Yizhi; Amiram, Miriam; Gao, Weiping et al. (2013) Sortase-catalyzed initiator attachment enables high yield growth of a stealth polymer from the C terminus of a protein. Macromol Rapid Commun 34:1256-60
Folk, Drew S; Torosian, Justin C; Hwang, Sunhee et al. (2012) Monitoring ýý-secretase activity in living cells with a membrane-anchored FRET probe. Angew Chem Int Ed Engl 51:10795-9
Weinberg, David R; Gagliardi, Christopher J; Hull, Jonathan F et al. (2012) Proton-coupled electron transfer. Chem Rev 112:4016-93
Hoertz, Amanda J; Hamburger, James B; Gooden, David M et al. (2012) Studies on the biosynthesis of the lipodepsipeptide antibiotic Ramoplanin A2. Bioorg Med Chem 20:859-65
Jorgensen, Ine; Bednar, Maria M; Amin, Vishar et al. (2011) The Chlamydia protease CPAF regulates host and bacterial proteins to maintain pathogen vacuole integrity and promote virulence. Cell Host Microbe 10:21-32
Hu, Xiangqian; Hu, Hao; Melvin, Jeffrey A et al. (2011) Autocatalytic intramolecular isopeptide bond formation in gram-positive bacterial pili: a QM/MM simulation. J Am Chem Soc 133:478-85
Melvin, Jeffrey A; Murphy, Christine F; Dubois, Laura G et al. (2011) Staphylococcus aureus sortase A contributes to the Trojan horse mechanism of immune defense evasion with its intrinsic resistance to Cys184 oxidation. Biochemistry 50:7591-9
Cropp, T Ashton; McCafferty, Dewey G (2011) Found in translation: applications of protein and peptide molecular diversity. Curr Opin Chem Biol 15:347-9
Bednar, Maria M; Jorgensen, Ine; Valdivia, Raphael H et al. (2011) Chlamydia protease-like activity factor (CPAF): characterization of proteolysis activity in vitro and development of a nanomolar affinity CPAF zymogen-derived inhibitor. Biochemistry 50:7441-3

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