Upon pulmonary infection of CF patients, Pseudomonas aeruginosa undergoes mucoid conversion and acquires the ability to cause chronic, debilitating, and life-threatening disease. The mucoid phenotype is due to the overproduction of alginate, a capsule-like exopolysaccharide that confers resistance to phagocytosis and new adherence properties. Adaptive mutations occur in vivo to de-repress an alternative ECF sigma factor, sigma-22, which leads to the overproduction of alginate. Our long term goal is to characterize the complex regulatory pathways that respond to stress and lead to the activation of genes for alginate biosynthesis. A simple bioassay was developed to test for activation of the promoter of the alginate biosynthetic operon, PalgD. We have discovered that exposure of P. aeruginosa to antibiotics that interfere with cell wall synthesis activates PalgD. This response to cell wall stress requires sigma-22 and the two- component regulators, AlgB and AlgR. In addition, the AlgW protease (a homogue of DegS in E. coli) is also required for the activation of PalgD in cell wall stress response. These discoveries provide valuable new tools and important insights into our understanding the mechanism of sigma-22 control of alginate in P. aeruginosa. We will pursue 3 aims directed at understanding the activation of alginate gene expression: 1. Elucidate the mechanism of regulated proteolysis that activates sigma-22 under conditions of cell wall stress. 2. Characterize the stress signals elicited by antibiotics that affect cell wall homeostasis and activate genes for alginate biosynthesis. 3. Define the role of the 2-component regulator, AlgB, in the alginate gene regulon. These studies will greatly improve our understanding of the complex regulatory pathway that induces alginate production in P. aeruginosa and may lead to novel therapeutic approaches.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI019146-26
Application #
7794930
Study Section
Bacterial Pathogenesis Study Section (BACP)
Program Officer
Taylor, Christopher E,
Project Start
1982-09-01
Project End
2012-03-31
Budget Start
2010-04-01
Budget End
2011-03-31
Support Year
26
Fiscal Year
2010
Total Cost
$319,703
Indirect Cost
Name
Virginia Commonwealth University
Department
Microbiology/Immun/Virology
Type
Schools of Medicine
DUNS #
105300446
City
Richmond
State
VA
Country
United States
Zip Code
23298
Wang, Congzhou; Zolotarskaya, Olga Y; Nair, Sithara S et al. (2016) Real-Time Observation of Antimicrobial Polycation Effects on Escherichia coli: Adapting the Carpet Model for Membrane Disruption to Quaternary Copolyoxetanes. Langmuir 32:2975-84
Wood, Lynn F; Ohman, Dennis E (2015) Cell wall stress activates expression of a novel stress response facilitator (SrfA) under ?22 (AlgT/U) control in Pseudomonas aeruginosa. Microbiology 161:30-40
Whitney, John C; Whitfield, Gregory B; Marmont, Lindsey S et al. (2015) Dimeric c-di-GMP is required for post-translational regulation of alginate production in Pseudomonas aeruginosa. J Biol Chem 290:12451-62
Silo-Suh, Laura A; Suh, Sang-Jin; Ohman, Dennis E et al. (2015) Complete Genome Sequence of Pseudomonas aeruginosa Mucoid Strain FRD1, Isolated from a Cystic Fibrosis Patient. Genome Announc 3:
King, Allison; Chakrabarty, Souvik; Zhang, Wei et al. (2014) High antimicrobial effectiveness with low hemolytic and cytotoxic activity for PEG/quaternary copolyoxetanes. Biomacromolecules 15:456-67
Baker, Perrin; Ricer, Tyler; Moynihan, Patrick J et al. (2014) P. aeruginosa SGNH hydrolase-like proteins AlgJ and AlgX have similar topology but separate and distinct roles in alginate acetylation. PLoS Pathog 10:e1004334
Riley, Laura M; Weadge, Joel T; Baker, Perrin et al. (2013) Structural and functional characterization of Pseudomonas aeruginosa AlgX: role of AlgX in alginate acetylation. J Biol Chem 288:22299-314
Sautter, Robert; Ramos, Damaris; Schneper, Lisa et al. (2012) A complex multilevel attack on Pseudomonas aeruginosa algT/U expression and algT/U activity results in the loss of alginate production. Gene 498:242-53
Wood, Lynn F; Ohman, Dennis E (2012) Identification of genes in the ýýýýýý regulon of Pseudomonas aeruginosa required for cell envelope homeostasis in either the planktonic or the sessile mode of growth. MBio 3:
Paletta, Janice L; Ohman, Dennis E (2012) Evidence for two promoters internal to the alginate biosynthesis operon in Pseudomonas aeruginosa. Curr Microbiol 65:770-5

Showing the most recent 10 out of 39 publications