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Uracil influences quorum sensing and biofilm formation in Pseudomonas aeruginosa and fluorouracil is an antagonist.

ABSTRACT: Pseudomonas aeruginosa is an ubiquitous, opportunistic pathogen whose biofilms are notoriously difficult to control. Here we discover uracil influences all three known quorum-sensing (QS) pathways of P. aeruginosa. By screening 5850 transposon mutants for altered biofilm formation, we identified seven uracil-related mutations that abolished biofilm formation. Whole-transcriptome studies showed the uracil mutations (e.g. pyrF that catalyses the last step in uridine monophosphate synthesis) alter the regulation of all three QS pathways [LasR-, RhlR- and 2-heptyl-3-hydroxy-4-quinolone (PQS)-related regulons]; addition of extracellular uracil restored global wild-type regulation. Phenotypic studies confirmed uracil influences the LasR (elastase), RhlR (pyocyanin, rhamnolipids), PQS and swarming regulons. Our results also demonstrate uracil influences virulence (the pyrF mutant was less virulent to barley). Additionally, we found an anticancer uracil analogue, 5-fluorouracil, that repressed biofilm formation, abolished QS phenotypes and reduced virulence. Hence, we have identified a central regulator of an important pathogen and a potential novel class of efficacious drugs for controlling cellular behaviour (e.g. biofilm formation and virulence).

SUBMITTER: Ueda A

PROVIDER: S-EPMC3815422 | biostudies-literature | 2009 Jan

REPOSITORIES: biostudies-literature

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Uracil influences quorum sensing and biofilm formation in Pseudomonas aeruginosa and fluorouracil is an antagonist.

Ueda Akihiro A Attila Can C Whiteley Marvin M Wood Thomas K TK

Microbial biotechnology 20081013 1

Pseudomonas aeruginosa is an ubiquitous, opportunistic pathogen whose biofilms are notoriously difficult to control. Here we discover uracil influences all three known quorum-sensing (QS) pathways of P. aeruginosa. By screening 5850 transposon mutants for altered biofilm formation, we identified seven uracil-related mutations that abolished biofilm formation. Whole-transcriptome studies showed the uracil mutations (e.g. pyrF that catalyses the last step in uridine monophosphate synthesis) alter ...[more]

PMID: 21261882

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Project description:With the opportunistic pathogen Pseudomonas aeruginosa, quorum sensing based on homoserine lactones was found to influence biofilm formation. Here we discern a mechanism by which quorum sensing controls biofilm formation by screening 5850 transposon mutants of P. aeruginosa PA14 for altered biofilm formation. This screen identified the PA3885 mutant, which had 147-fold more biofilm than the wild-type strain. Loss of PA3885 decreased swimming, abolished swarming, and increased attachment, although this did not affect production of rhamnolipids. The PA3885 mutant also had a wrinkly colony phenotype, formed pronounced pellicles, had substantially more aggregation, and had 28-fold more exopolysaccharide production. Expression of PA3885 in trans reduced biofilm formation and abolished aggregation. Whole transcriptome analysis showed that loss of PA3885 activated expression of the pel locus, an operon that encodes for the synthesis of extracellular matrix polysaccharide. Genetic screening identified that loss of PelABDEG and the PA1120 protein (which contains a GGDEF-motif) suppressed the phenotypes of the PA3885 mutant, suggesting that the function of the PA3885 protein is to regulate 3,5-cyclic diguanylic acid (c-di-GMP) concentrations as a phosphatase since c-di-GMP enhances biofilm formation by activating PelD, and c-di-GMP inhibits swarming. Loss of PA3885 protein increased cellular c-di-GMP concentrations; hence, PA3885 protein is a negative regulator of c-di-GMP production. Purified PA3885 protein has phosphatase activity against phosphotyrosine peptides and is translocated to the periplasm. Las-mediated quorum sensing positively regulates expression of the PA3885 gene. These results show that the PA3885 protein responds to AHL signals and likely dephosphorylates PA1120, which leads to reduced c-di-GMP production. This inhibits matrix exopolysaccharide formation, which leads to reduced biofilm formation; hence, we provide a mechanism for quorum sensing control of biofilm formation through the pel locus and suggest PA3885 should be named TpbA for tyrosine phosphatase related to biofilm formation and PA1120 should be TpbB.

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Uracil influences quorum sensing and biofilm formation in Pseudomonas aeruginosa and fluorouracil is an antagonist.

Publications

Uracil influences quorum sensing and biofilm formation in Pseudomonas aeruginosa and fluorouracil is an antagonist.

Similar Datasets

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