Quorum sensing is one mechanism by which many pathogenic bacteria coordinate gene expression. At high cell densities, signaling by the las and rhl quorum sensing systems of Pseudomonas aeruginosa induces the expression of approximately 300 genes, including numerous virulence genes. With addition of exogenous quorum sensing signals, some genes, such as hcnABC (encoding hydrogen cyanide synthase) are induced early in growth while others, such as lasB (encoding elastase) are expressed late in growth. I propose that the affinity of quorum-controlled gene promoters for the transcriptional regulators encoded by the quorum systems determines the timing of their induction. The contribution of individual regulator binding sites within the lasB and hcnA promoters to induction timing will be determined by deletion, mutation, or rearrangement of these sites in the presence of varying levels of the transcriptional regulator encoded by the las system, LasR. LasR will be purified and used in gel shift assays to determine the affinity of the lasB and hcnA promoters for LasR, in DNAse protection assays to assess potential cooperative binding of LasR by multiple sites in the lasB and hcnA promoters, and in in vitro transcription assays. Affinity of these promoters for LasR will then be correlated to induction timing.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Postdoctoral Individual National Research Service Award (F32)
Project #
1F32GM069110-01
Application #
6691374
Study Section
Special Emphasis Panel (ZRG1-F08 (20))
Program Officer
Wolfe, Paul B
Project Start
2003-08-01
Project End
2005-04-30
Budget Start
2003-08-01
Budget End
2004-07-31
Support Year
1
Fiscal Year
2003
Total Cost
$41,608
Indirect Cost
Name
University of Iowa
Department
Microbiology/Immun/Virology
Type
Schools of Medicine
DUNS #
062761671
City
Iowa City
State
IA
Country
United States
Zip Code
52242
Yarwood, Jeremy M; Volper, Esther M; Greenberg, E Peter (2005) Delays in Pseudomonas aeruginosa quorum-controlled gene expression are conditional. Proc Natl Acad Sci U S A 102:9008-13
Yarwood, Jeremy M; Schlievert, Patrick M (2003) Quorum sensing in Staphylococcus infections. J Clin Invest 112:1620-5