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‣ A chemosensory system that regulates biofilm formation through modulation of cyclic diguanylate levels

Hickman, Jason W.; Tifrea, Delia F.; Harwood, Caroline S.
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
515.60055%
Pseudomonas aeruginosa causes chronic biofilm infections, and its ability to attach to surfaces and other cells is important for biofilm formation and maintenance. Mutations in a gene called wspF, part of a putative chemosensory signal-transduction operon, have been shown to result in cell aggregation and altered colony morphology. The WspF phenotypes depend on the presence of WspR, which is a member of a family of signal transduction proteins known as response regulators. It is likely that the effect of the wspF mutation is to cause constitutive activation of WspR by phosphorylation. WspR contains a GGDEF domain known to catalyze formation of a cytoplasmic signaling molecule cyclic diguanylate (c-diGMP). We determined that purified WspR catalyzed the formation of c-diGMP in vitro and phosphorylation stimulated this activity. We observed increased cellular levels of c-diGMP and increased biofilm formation in a wspF mutant. Expression of a protein predicted to catalyze degradation of c-diGMP reversed the phenotypes of a wspF mutant and inhibited biofilm initiation by wild-type cells, indicating that the presence of c-diGMP is necessary for biofilm formation. A transcriptome analysis showed that expression levels of at least 560 genes were affected by a wspF deletion. The psl and pel operons...

‣ Oligoribonuclease is a central feature of cyclic diguanylate signaling in Pseudomonas aeruginosa

Cohen, Dorit; Mechold, Undine; Nevenzal, Hadas; Yarmiyhu, Yafit; Randall, Trevor E.; Bay, Denice C.; Rich, Jacquelyn D.; Parsek, Matthew R.; Kaever, Volkhard; Harrison, Joe J.; Banin, Ehud
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
501.15047%
Many bacteria possess enzymes that synthesize and degrade the intracellular second messenger cyclic diguanylate (c-di-GMP). Bacteria use this molecule to relay environmental signals into physiological responses that control motility, virulence, and biofilm formation. There are two pathways for enzymatic c-di-GMP degradation. One of these pathways involves the production of an intermediate molecule called 5ʹ-phosphoguanylyl-(3ʹ,5ʹ)-guanosine (pGpG). Although many enzymes responsible for c-di-GMP degradation have been characterized, microbiologists have long sought those responsible for pGpG degradation. Here we identify that oligoribonuclease (Orn) mediates pGpG degradation and show that Orn is important for c-di-GMP signaling in the human pathogen Pseudomonas aeruginosa. This discovery reveals that nanoribonucleases, which have been considered housekeeping proteins crucial for mRNA turnover, also have a key role in c-di-GMP signaling.