Tricarboxylic Acid Cycle-Dependent Regulation of Staphylococcus epidermidis Polysaccharide Intercellular Adhesin Synthesis

Authors

Marat R. Sadykov, University of Nebraska—Lincoln
Michael E. Olson, University of Nebraska Medical Center
Steven M. Halouska, University of Nebraska-LincolnFollow
Yefei Zhu, University of Nebraska - Lincoln
Paul D. Fey, University of Nebraska Medical CenterFollow
Robert Powers, University of Nebraska-LincolnFollow
Greg A. Somerville, University of Nebraska-LincolnFollow

Date of this Version

2008

Citation

JOURNAL OF BACTERIOLOGY, Dec. 2008, p. 7621–7632

Comments

© 2008, American Society for Microbiology. All Rights Reserved.

Abstract

Staphylococcus epidermidis is a major nosocomial pathogen primarily infecting immunocompromised individuals or those with implanted biomaterials (e.g., catheters). Biomaterial-associated infections often involve the formation of a biofilm on the surface of the medical device. In S. epidermidis, polysaccharide intercellular adhesin (PIA) is an important mediator of biofilm formation and pathogenesis. Synthesis of PIA is regulated by at least three DNA binding proteins (IcaR, SarA, and σ^B) and several environmental and nutritional conditions. Previously, we observed the environmental conditions that increased PIA synthesis decreased tricarboxylic acid (TCA) cycle activity. In this study, S. epidermidis TCA cycle mutants were constructed, and the function of central metabolism in PIA biosynthesis was examined. TCA cycle inactivation altered the metabolic status of S. epidermidis, resulting in a massive derepression of PIA biosynthetic genes and a redirection of carbon from growth into PIA biosynthesis. These data demonstrate that the bacterial metabolic status is a critical regulatory determinant of PIA synthesis. In addition, these data lead us to propose that the TCA cycle acts as a signal transduction pathway to translate external environmental cues into intracellular metabolic signals that modulate the activity of transcriptional regulators.