The Pseudomonas aeruginosa efflux pump MexGHI-OpmD transports a natural phenazine that controls gene expression and biofilm development.
Redox-cycling compounds, including endogenously produced phenazine antibiotics, induce expression of the efflux pump MexGHI-OpmD in the opportunistic pathogen Pseudomonas aeruginosa Previous studies of P. aeruginosa virulence, physiology, and biofilm development have focused on the blue phenazine pyocyanin and the yellow phenazine-1-carboxylic acid (PCA). In P. aeruginosa phenazine biosynthesis, conversion of PCA to pyocyanin is presumed to proceed through the intermediate 5-methylphenazine-1-carboxylate (5-Me-PCA), a reactive compound that has eluded detection in most laboratory samples. Here, we apply electrochemical methods to directly detect 5-Me-PCA and find that it is transported by MexGHI-OpmD in P. aeruginosa strain PA14 planktonic and biofilm cells. We also show that 5-Me-PCA is sufficient to fully induce MexGHI-OpmD expression and that it is required for wild-type colony biofilm morphogenesis. These physiological effects are consistent with the high redox potential of 5-Me-PCA, which distinguishes it from other well-studied P. aeruginosa phenazines. Our observations highlight the importance of this compound, which was previously overlooked due to the challenges associated with its detection, in the context of P. aeruginosa gene expression and multicellular behavior. This study constitutes a unique demonstration of efflux-based self-resistance, controlled by a simple circuit, in a Gram-negative pathogen.
Department of Biological Sciences, Columbia University, New York, NY 10027;
Hassan
H
Sakhtah
Department of Biological Sciences, Columbia University, New York, NY 10027;
Leslie
L
Koyama
Department of Electrical Engineering, Columbia University, New York, NY 10027;
Yihan
Y
Zhang
Department of Biological Sciences, Columbia University, New York, NY 10027; Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755.
Diana K
DK
Morales
Department of Biological Sciences, Columbia University, New York, NY 10027;
Blanche L
BL
Fields
Department of Biological Sciences, Columbia University, New York, NY 10027;
Alexa
A
Price-Whelan
Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755.
Deborah A
DA
Hogan
Department of Electrical Engineering, Columbia University, New York, NY 10027;
Kenneth
K
Shepard
Department of Biological Sciences, Columbia University, New York, NY 10027; LDietrich@columbia.edu.
Lars E P
LE
Dietrich
D001426:Bacterial Proteins / Q000502:physiology*; D018441:Biofilms / Q000254:growth & development*; D002352:Carrier Proteins / Q000502:physiology*; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology*; D010619:Phenazines / Q000378:metabolism*; D011550:Pseudomonas aeruginosa / Q000378:metabolism*
C000601497:5-methylphenazine-1-carboxylic acid; D001426:Bacterial Proteins; D002352:Carrier Proteins; D010619:Phenazines
MexGHI-OpmD; RND efflux; antibiotic; biofilm; phenazine