Activation and Transcriptional Interaction betweenagrRNAII and RNAIII inStaphylococcus aureusIn Vitro and in an Experimental Endocarditis Model

  • Yan-Qiong, Xiong
  • William, Van Wamel
  • Cynthia, Nast C.
  • Michael, Yeaman R.
  • Ambrose, Cheung L.
  • Arnold, Bayer S.

  • 1Division of Infectious Diseases, Harbor-University of California, Los Angeles, Research and Education Institute, Torrance, and

    2Department of Pathology, Cedars-Sinai Medical Center, and

    3School of Medicine, University of California, Los Angeles;

    4Department of Microbiology and Immunology, Dartmouth Medical School, Hanover, New Hampshire

Reprints or correspondence: Dr. Ambrose L. Cheung, Dept. of Microbiology and Immunology, Dartmouth Medical School, 206 Vail, Hanover, NH 03755 ([email protected])

Received 3 January 2002; revised 24 April 2002

Presented in part: 101st general meeting of the American Society for Microbiology, Orlando, Florida, 20-24 May 2001 (abstract D-83)

Financial support: National Institutes of Health (AI-47441 to A.L.C., AI-39108 to A.S.B., and AI-48031 and RR-13004 to M.R.Y.)

Journal of Infectious Diseases 186(5):p 668-677, September 1, 2002. | DOI: 10.1086/342046

This study compared the promoter activation profiles of the 2 major transcripts of the Staphylococcus aureus global regulon, agr (RNAII and RNAIII). In vitro, RNAIII activation temporally followed RNAII activation and was absent in agr mutants. In experimental endocarditis, maximal RNAII activation in vegetations occurred early, followed by progressive increases in RNAIII activation (P<.05; 2 vs. 48 h); this paralleled significant increases in vegetation bacterial densities over time (P<.05; 2 and 6 vs. 48 h). At 48 h of infection, S. aureus densities in vegetations were significantly higher than those in kidney or spleen tissue (P<.05), paralleling a significantly greater RNAIII activation profile in vegetations than in the latter tissues (P<.05). Of importance, RNAIII activation was observed in vegetations in 2 agr mutants. These data demonstrate that RNAIII activation in vivo is time and cell density dependent, may be tissue specific, and can occur through RNAII-dependent and -independent mechanisms

Copyright © Copyright Oxford University Press 2002.