: Staphylococcus aureus is a virulent pathogen which is associated with a broad-spectrum of clinical infections. Its ability to colonize host tissues, and to persist and proliferate within host tissues requires the organism to circumvent innate host defense mechanisms. We have discovered that mammalian platelets store and secrete a family of antimicrobial peptides at potential sites of endovascular damage and microbial colonization that serve to both growth inhibit and kill S. aureus. In the previous grant period, we have delineated that the principal antimicrobial peptide which is secreted from platelets (thrombin-induced platelet microbicidal protein-1 [tPMP-1]), interacts with S. aureus in vitro by initial attachment to the cytoplasmic membrane, after which a microbicidal cascade is triggered in strains intrinsically susceptible to this peptide. In contrast, those strains which were engineered to be resistant to tPMP-1 in vitro (e.g., by transposon mutagenesis) do so by changing the basic biology of their cytoplasmic membrane target for tPMP-1. In vitro susceptibility to tPMP-1 is mirrored by enhanced clearance of such strains in animal models of endovascular infection; in contrast, in vitro resistance to tPMP-1 is correlated with an augmented survival advantage in the same animal models. The overall purposes of this proposal are: i) to define the mechanisms by which tPMP-1 executes its microbicidal effects, particularly focusing on intracellular targeting and activation of stress response systems; and ii) to delineate the mechanisms, genetic pathways and membrane biochemical adaptations by which the organism is able to successfully respond to exposures to tPMP-1 for survival. For these purposes, we will utilize a series of well-characterized and isogenic strain pairs of S. aureus (including site-directed plasmid mutants, as well as mutants with plasmid reporter fusions) that will enable us to define both the mechanisms of microbicidal action of tPMP-1, as well as the homeostatic adaptive pathways used by the organism to survive tPMP-1 exposures. Moreover, we will employ proteomics approaches to divulge novel genes and metabolic pathways triggered by tPMP-1 as part of either its microbicidal cascade, or as part of the organism's adaptive strategies. These studies will provide a solid foundation for the future design of unique platelet peptide congeners which are better able to target S. aureus strains for killing, as well as to circumvent innate homeostatic mechanisms used by the organism for survival.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI039108-08
Application #
6826800
Study Section
Bacteriology and Mycology Subcommittee 2 (BM)
Program Officer
Peters, Kent
Project Start
1996-12-01
Project End
2006-11-30
Budget Start
2004-12-01
Budget End
2005-11-30
Support Year
8
Fiscal Year
2005
Total Cost
$301,450
Indirect Cost
Name
La Biomed Research Institute/ Harbor UCLA Medical Center
Department
Type
DUNS #
069926962
City
Torrance
State
CA
Country
United States
Zip Code
90502
Yang, Soo-Jin; Mishra, Nagendra N; Kang, Kyoung-Mi et al. (2018) Impact of Multiple Single-Nucleotide Polymorphisms Within mprF on Daptomycin Resistance in Staphylococcus aureus. Microb Drug Resist 24:1075-1081
Abdelhady, Wessam; Bayer, Arnold S; Gonzales, Rachelle et al. (2017) Telavancin Is Active against Experimental Aortic Valve Endocarditis Caused by Daptomycin- and Methicillin-Resistant Staphylococcus aureus Strains. Antimicrob Agents Chemother 61:
Mishra, Nagendra N; Tran, Truc T; Seepersaud, Ravin et al. (2017) Perturbations of Phosphatidate Cytidylyltransferase (CdsA) Mediate Daptomycin Resistance in Streptococcus mitis/oralis by a Novel Mechanism. Antimicrob Agents Chemother 61:
Kang, Kyoung-Mi; Mishra, Nagendra N; Park, Kun Taek et al. (2017) Phenotypic and genotypic correlates of daptomycin-resistant methicillin-susceptible Staphylococcus aureus clinical isolates. J Microbiol 55:153-159
Xiong, Yan Q; Abdelhady, Wessam; Tang, Chieh 'Genna' et al. (2016) Comparative efficacy of telavancin and daptomycin in experimental endocarditis due to multi-clonotype MRSA strains. J Antimicrob Chemother 71:2890-4
Miller, William R; Bayer, Arnold S; Arias, Cesar A (2016) Mechanism of Action and Resistance to Daptomycin in Staphylococcus aureus and Enterococci. Cold Spring Harb Perspect Med 6:
Chaili, Siyang; Cheung, Ambrose L; Bayer, Arnold S et al. (2016) The GraS Sensor in Staphylococcus aureus Mediates Resistance to Host Defense Peptides Differing in Mechanisms of Action. Infect Immun 84:459-66
Khatib, Tala O; Stevenson, Heather; Yeaman, Michael R et al. (2016) Binding of Daptomycin to Anionic Lipid Vesicles Is Reduced in the Presence of Lysyl-Phosphatidylglycerol. Antimicrob Agents Chemother 60:5051-3
Bayer, Arnold S; Mishra, Nagendra N; Cheung, Ambrose L et al. (2016) Dysregulation of mprF and dltABCD expression among daptomycin-non-susceptible MRSA clinical isolates. J Antimicrob Chemother 71:2100-4
Li, Liang; Cheung, Ambrose; Bayer, Arnold S et al. (2016) The Global Regulon sarA Regulates ?-Lactam Antibiotic Resistance in Methicillin-Resistant Staphylococcus aureus In Vitro and in Endovascular Infections. J Infect Dis 214:1421-1429

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