Quorum sensing (QS) has evolved as a means for bacterial communities to regulate gene expression in response to environmental cues in a coordinated manner. Each cell of the population produces and secretes signaling molecules, called autoinducers, and responds to these molecules, which thus serve as indicators of the population density. QS circuits control complex bacterial behaviors, such as bioluminescence, virulence, antibiotic resistance, and biofilm formation. QS systems have been discovered in Gram-negative and -positive bacteria and a variety of molecules, e.g. oligopeptides and acyl homoserine lactones, have been identified as autoinducers. A distinct third class of QS molecules are autoinducers derived from the precursor (S)-4,5-dihydroxy-2,3-pentanedione (DPD). So far, two distinct members of this family have been structurally identified. The luxS gene encoding the enzyme responsible for the final step in the biosynthesis of DPD, has been identified in over 55 bacterial species, both Gram-positive and -negative bacteria, including many clinically relevant pathogens. We have designed a series of chemical, biochemical, and biological experiments to examine and evaluate the molecular mechanisms that define AI-2 recognition by bacterial cells. In addition these investigations will help elucidate the bioactivity of DPD in bacterial systems, as well as to obtain molecules that possess agonistic or antagonistic signaling activity.
The specific aims of our proposal are: 1) Synthesis of DPD/AI-2 Agonists and Antagonists;2) Mechanistic Investigations of DPD-mediated Effects in Pathogenic Bacteria;3) Elucidation of the Cellular Recognition of AI-2;and 4) Proteomic analysis of AI-2 Quorum Sensing-regulated Processes. In total, we believe that the use of synthetic DPD and systematically designed analogs of DPD/AI-2 in the experimental methodologies outlined in this proposal will provide new biochemical and microbiological insights into DPD-/AI-2-based QS systems and will help to evaluate the therapeutic value of AI-2-dependent QS as new leads for the antibacterial strategies.

Public Health Relevance

Microbial cell-to-cell signaling has been coined quorum sensing. It controls many bacterial processes, such as antibiotic resistance and biofilm formation, which represents a majority of disease states where chronic bacterial infection leads to tissue destruction and loss of organ function. This includes diseases as diverse as dental caries, wound infections, and even anthrax. This proposal is designed to gain insight into the molecular details of quorum sensing and to develop countermeasures to prevent quorum sensing signaling in a wide number of bacteria.

Agency
National Institute of Health (NIH)
Type
Research Project (R01)
Project #
5R01AI077644-05
Application #
8660596
Study Section
Drug Discovery and Mechanisms of Antimicrobial Resistance Study Section (DDR)
Program Officer
Hall, Robert H
Project Start
Project End
Budget Start
Budget End
Support Year
5
Fiscal Year
2014
Total Cost
Indirect Cost
Name
Scripps Research Institute
Department
Type
DUNS #
City
La Jolla
State
CA
Country
United States
Zip Code
92037
Garner, Amanda L; Yu, Jing; Struss, Anjali K et al. (2013) Immunomodulation and the quorum sensing molecule 3-oxo-C12-homoserine lactone: the importance of chemical scaffolding for probe development. Chem Commun (Camb) 49:1515-7
Zhu, Jie; Hixon, Mark S; Globisch, Daniel et al. (2013) Mechanistic insights into the LsrK kinase required for autoinducer-2 quorum sensing activation. J Am Chem Soc 135:7827-30
Garner, Amanda L; Fullagar, Jessica L; Day, Joshua A et al. (2013) Development of a high-throughput screen and its use in the discovery of Streptococcus pneumoniae immunoglobulin A1 protease inhibitors. J Am Chem Soc 135:10014-7
Kravchenko, Vladimir; Garner, Amanda L; Mathison, John et al. (2013) Facilitating Cytokine-Mediated Cancer Cell Death by Proteobacterial N-Acylhomoserine Lactones. ACS Chem Biol :
Lowery, Colin A; Matamouros, Susana; Niessen, Sherry et al. (2013) A chemical biology approach to interrogate quorum-sensing regulated behaviors at the molecular and cellular level. Chem Biol 20:903-11
Kravchenko, Vladimir V; Gloeckner, Christian; Stowe, G Neil et al. (2012) The use of small molecule probes to study spatially separated stimulus-induced signaling pathways. Bioorg Med Chem Lett 22:2043-5
Romano, Ariel A; Hahn, Tobias; Davis, Nicole et al. (2012) The Fe(III) and Ga(III) coordination chemistry of 3-(1-hydroxymethylidene) and 3-(1-hydroxydecylidene)-5-(2-hydroxyethyl)pyrrolidine-2,4-dione: novel tetramic acid degradation products of homoserine lactone bacterial quorum sensing molecules. J Inorg Biochem 107:96-103
Garner, Amanda L; Park, Junguk; Zakhari, Joseph S et al. (2011) A multivalent probe for AI-2 quorum-sensing receptors. J Am Chem Soc 133:15934-7
Tsuchikama, Kyoji; Lowery, Colin A; Janda, Kim D (2011) Probing autoinducer-2 based quorum sensing: the biological consequences of molecules unable to traverse equilibrium states. J Org Chem 76:6981-9
Zakhari, Joseph S; Kinoyama, Isao; Struss, Anjali K et al. (2011) Synthesis and molecular modeling provide insight into a Pseudomonas aeruginosa quorum sensing conundrum. J Am Chem Soc 133:3840-2

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