Staphylococcus aureus and Staphylococcus epidermidis are opportunistic bacterial pathogens responsible for a wide array of human and animal diseases. Importantly, S. aureus and S. epidermidis are the two leading causes of hospital-associated infections, which significantly increase morbidity and treatment costs. Exopolysaccharides are important mediators of staphylococcal infections;specifically, polysaccharide intercellular adhesin (PIA) enhances biofilm formation and immune evasion, while capsule facilitates immune evasion, colonization, and persistence. Staphylococcal PIA is synthesized when tricarboxylic acid (TCA) cycle activity is repressed. In contrast, synthesis of the S. aureus capsular polysaccharide requires TCA cycle activity. Interestingly, PIA and capsule are derived from the same amino sugar (i.e., UDP-N-acetyl-glucosamine. Synthesis of both exopolysaccharides is modulated by the availability of nutrients, oxygen, and iron. Similarly, TCA cycle activity is regulated by the availability of nutrients, oxygen, and iron and by certain stress-inducing stimuli such as heat, ethanol, and antibiotics. The linkage of TCA cycle activity and exopolysaccharide synthesis and the susceptibility of the TCA cycle to environmental inactivation lead us to hypothesize that one mechanism by which staphylococci perceive external environmental change is through alterations in TCA cycle activity. These changes in TCA cycle activity alter the bacterial metabolome increasing or decreasing the intracellular concentrations of metabolites and co- factors that are "sensed" by regulatory proteins, which increase or decrease exopolysaccharide biosynthesis.
The aims of this proposal are to identify the TCA cycle metabolites that control exopolysaccharide synthesis and determine which regulatory proteins are responding to these TCA cycle metabolites to regulate exopolysaccharide synthesis. To achieve these aims, we will use an integrated approach combining systems biology, biochemistry, bioinformatics, and genetics. The rationale for the proposed research is to fill the gap in our understanding of how environmental conditions affect the bacterial metabolic status and, in turn, how the metabolic status affects staphylococcal exopolysaccharide biosynthesis. Understanding this will aid in our long-term goal, which is to design therapeutic strategies targeting staphylococcal metabolism and metabolic responsive regulators that will facilitate bacterial killing by antibiotics and the host immune system.

Public Health Relevance

Many bacterial infections are difficult for physicians treat because the bacteria can produce a thick layer of slime. Slime is comprised of a complex sugar chain that prevents antibiotics and your immune system from killing the bacteria. The work contained in this proposal is a first step toward inhibiting the formation of this complex sugar chain and providing physicians new ways to treat patients.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI087668-03
Application #
8260856
Study Section
Bacterial Pathogenesis Study Section (BACP)
Program Officer
Huntley, Clayton C
Project Start
2010-05-01
Project End
2014-04-30
Budget Start
2012-05-01
Budget End
2013-04-30
Support Year
3
Fiscal Year
2012
Total Cost
$350,478
Indirect Cost
$102,978
Name
University of Nebraska Lincoln
Department
Veterinary Sciences
Type
Schools of Earth Sciences/Natur
DUNS #
555456995
City
Lincoln
State
NE
Country
United States
Zip Code
68588
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Halouska, Steven; Fenton, Robert J; Zinniel, Denise K et al. (2014) Metabolomics analysis identifies d-Alanine-d-Alanine ligase as the primary lethal target of d-Cycloserine in mycobacteria. J Proteome Res 13:1065-76
Stark, Jaime L; Copeland, Jennifer C; Eletsky, Alexander et al. (2014) Identification of low-molecular-weight compounds inhibiting growth of corynebacteria: potential lead compounds for antibiotics. ChemMedChem 9:282-5
Hartmann, Torsten; Baronian, Grégory; Nippe, Nadine et al. (2014) The catabolite control protein E (CcpE) affects virulence determinant production and pathogenesis of Staphylococcus aureus. J Biol Chem 289:29701-11
Worley, Bradley; Powers, Robert (2014) MVAPACK: a complete data handling package for NMR metabolomics. ACS Chem Biol 9:1138-44
Somerville, Greg A; Powers, Robert (2014) Growth and preparation of Staphylococcus epidermidis for NMR metabolomic analysis. Methods Mol Biol 1106:71-91
Worley, Bradley; Powers, Robert (2014) Simultaneous Phase and Scatter Correction for NMR Datasets. Chemometr Intell Lab Syst 131:1-6
Shah, Neethu; Gaupp, Rosmarie; Moriyama, Hideaki et al. (2013) Reductive evolution and the loss of PDC/PAS domains from the genus Staphylococcus. BMC Genomics 14:524
Worley, Bradley; Halouska, Steven; Powers, Robert (2013) Utilities for quantifying separation in PCA/PLS-DA scores plots. Anal Biochem 433:102-4

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