Antibiotic-resistant Gram-positive bacteria, such as Enterococcus faecalis and Staphylococcus aureus, are major causes of hospital-acquired infections. E. faecalis is a successful hospital-acquired pathogen partly due to its intrinsic resistance to commonly used antibiotics that target bacterial cell envelope biogenesis. However, many questions regarding the genetic and biochemical basis for intrinsic antimicrobial resistance in E. faecalis remain unanswered. Preliminary studies identified a new signal transduction system containing a eukaryotic-type Ser/Thr kinase (PrkC) that is required for intrinsic antimicrobial resistance in E. faecalis. We hypothesize that PrkC monitors the cell envelope for perturbations caused by envelope-active antibiotics and mediates an adaptive biological response to produce antimicrobial resistance. Our long-term goal is to understand the role of this new signaling system in mediating resistance, and more generally, the genetic and biochemical basis for intrinsic antimicrobial resistance in E. faecalis. The objective of this proposal is to begin to elucidate the role of signal transduction, and specifically of the PrkC pathway, in mediating intrinsic antimicrobial resistance in enterococci. To achieve this goal, we will: 1) Define the PrkC-dependent regulatory circuit;2) Identify direct substrates for phosphorylation by PrkC;and 3) Characterize effectors of intrinsic antimicrobial resistance (the output of PrkC-dependent signaling). Thus, the research proposed here will provide insights into the function of a new bacterial signaling system, enhance fundamental understanding of the mechanisms responsible for antimicrobial resistance in Gram- positive bacteria, and form the foundation for future efforts to develop innovative therapies against infections caused by resistant bacteria.

Public Health Relevance

Antibiotic-resistant bacteria, such as Enterococcus faecalis and Staphylococcus aureus, are major causes of hospital-acquired infections. The research proposed here will enhance fundamental understanding of the mechanisms responsible for antimicrobial resistance in Gram-positive bacteria and form the foundation for future efforts to develop innovative therapies against infections caused by resistant bacteria.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI081692-05
Application #
8586291
Study Section
Drug Discovery and Mechanisms of Antimicrobial Resistance Study Section (DDR)
Program Officer
Huntley, Clayton C
Project Start
2009-12-01
Project End
2014-11-30
Budget Start
2013-12-01
Budget End
2014-11-30
Support Year
5
Fiscal Year
2014
Total Cost
$338,580
Indirect Cost
$115,830
Name
Medical College of Wisconsin
Department
Microbiology/Immun/Virology
Type
Schools of Medicine
DUNS #
937639060
City
Milwaukee
State
WI
Country
United States
Zip Code
53226
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Snyder, Holly; Kellogg, Stephanie L; Skarda, Laura M et al. (2014) Nutritional control of antibiotic resistance via an interface between the phosphotransferase system and a two-component signaling system. Antimicrob Agents Chemother 58:957-65
Vesic, Dusanka; Kristich, Christopher J (2013) A Rex family transcriptional repressor influences H2O2 accumulation by Enterococcus faecalis. J Bacteriol 195:1815-24
Hall, Cherisse L; Tschannen, Michael; Worthey, Elizabeth A et al. (2013) IreB, a Ser/Thr kinase substrate, influences antimicrobial resistance in Enterococcus faecalis. Antimicrob Agents Chemother 57:6179-86
Vesic, Dusanka; Kristich, Christopher J (2012) MurAA is required for intrinsic cephalosporin resistance of Enterococcus faecalis. Antimicrob Agents Chemother 56:2443-51
Kristich, Christopher J; Little, Jaime L (2012) Mutations in the ýý subunit of RNA polymerase alter intrinsic cephalosporin resistance in Enterococci. Antimicrob Agents Chemother 56:2022-7
Kristich, Christopher J; Little, Jaime L; Hall, Cherisse L et al. (2011) Reciprocal regulation of cephalosporin resistance in Enterococcus faecalis. MBio 2:e00199-11