Sleeping ribosomes: bacterial signaling triggers RaiA mediated persistence to aminoglycosides.

Salmonellaspp. are carried by and can acutely infect agricultural animals and humans. After ingestion, salmonellae traverse the upper digestive tract and initiate tissue invasion of the distal ileum, a virulence process carried out by the type III secretion system encoded withinSalmonellapathogenicity island 1 (SPI-1). Salmonellae coordinate SPI-1 expression with anatomical location via environmental cues, one of which is bile, a complex digestive fluid that causes potent repression of SPI-1 genes. The individual components of bile responsible for SPI-1 repression have not been previously characterized, nor have the bacterial signaling processes that modulate their effects been determined. Here, we characterize the mechanism by which bile represses SPI-1 expression. Individual bile acids exhibit repressive activity on SPI-1-regulated genes that requires neither passive diffusion nor OmpF-mediated entry. By using genetic methods, the effects of bile and bile acids were shown to require the invasion gene transcriptional activatorhilDand to function independently of known upstream signaling pathways. Protein analysis techniques showed that SPI-1 repression by bile acids is mediated by posttranslational destabilization of HilD. Finally, we found that bile acids function synergistically to achieve the overall repressive activity of bile. These studies demonstrate a common mechanism by which diverse environmental cues (e.g., certain short-chain fatty acids and bile acids) inhibit SPI-1 expression. These data provide information relevant toSalmonellapathogenesis during acute infection in the intestine and during chronic infection of the gallbladder and inform the basis for development of therapeutics to inhibit invasion as a means of repressingSalmonellapathogenicity.

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LuxR- and LuxI-Type Quorum-Sensing Circuits Are Prevalent in Members of the Populus deltoides Microbiome

Applied and Environmental Microbiology ◽

10.1128/aem.01417-13 ◽

2013 ◽

Vol 79 (18) ◽

pp. 5745-5752 ◽

Cited By ~ 34

Author(s):

Amy L. Schaefer ◽

Colin R. Lappala ◽

Ryan P. Morlen ◽

Dale A. Pelletier ◽

Tse-Yuan S. Lu ◽

...

Keyword(s):

Quorum Sensing ◽

Populus Deltoides ◽

Cell Communication ◽

Homoserine Lactone ◽

Bacterial Isolates ◽

Content Type ◽

Eastern Cottonwood ◽

Bacterial Signaling ◽

Signal Production ◽

Plant Signals

ABSTRACTWe are interested in the root microbiome of the fast-growing Eastern cottonwood tree,Populus deltoides. There is a large bank of bacterial isolates fromP. deltoides, and there are 44 draft genomes of bacterial endophyte and rhizosphere isolates. As a first step in efforts to understand the roles of bacterial communication and plant-bacterial signaling inP. deltoides, we focused on the prevalence of acyl-homoserine lactone (AHL) quorum-sensing-signal production and reception in members of theP. deltoidesmicrobiome. We screened 129 bacterial isolates for AHL production using a broad-spectrum bioassay that responds to many but not all AHLs, and we queried the available genome sequences of microbiome isolates for homologs of AHL synthase and receptor genes. AHL signal production was detected in 40% of 129 strains tested. Positive isolates included members of theAlpha-,Beta-, andGammaproteobacteria. Members of theluxIfamily of AHL synthases were identified in 18 of 39 proteobacterial genomes, including genomes of some isolates that tested negative in the bioassay. Members of theluxRfamily of transcription factors, which includes AHL-responsive factors, were more abundant thanluxIhomologs. There were 72 in the 39 proteobacterial genomes. Some of theluxRhomologs appear to be members of a subfamily of LuxRs that respond to as-yet-unknown plant signals rather than bacterial AHLs. Apparently, there is a substantial capacity for AHL cell-to-cell communication in proteobacteria of theP. deltoidesmicrobiota, and there are alsoProteobacteriawith LuxR homologs of the type hypothesized to respond to plant signals or cues.

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Intestinal Expression of Fas and Fas Ligand Is Upregulated by Bacterial Signaling through TLR4 and TLR5, with Activation of Fas Modulating Intestinal TLR-Mediated Inflammation

The Journal of Immunology ◽

10.4049/jimmunol.1303083 ◽

2014 ◽

Vol 193 (12) ◽

pp. 6103-6113 ◽

Cited By ~ 6

Author(s):

Philana Fernandes ◽

Charlotte O’Donnell ◽

Caitriona Lyons ◽

Jonathan Keane ◽

Tim Regan ◽

...

Keyword(s):

Fas Ligand ◽

Bacterial Signaling

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Manipulation of Bacterial Signaling Using Engineered Histidine Kinases

Methods in Molecular Biology - Histidine Phosphorylation ◽

10.1007/978-1-4939-9884-5_10 ◽

2019 ◽

pp. 141-163

Author(s):

Kimberly A. Kowallis ◽

Samuel W. Duvall ◽

Wei Zhao ◽

W. Seth Childers

Keyword(s):

Histidine Kinases ◽

Bacterial Signaling

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Sleeping ribosomes: bacterial signaling triggers RaiA mediated persistence to aminoglycosides

10.1101/2020.11.27.401281 ◽

2020 ◽

Author(s):

Manon Lang ◽

Evelyne Krin ◽

Chloé Korlowski ◽

Odile Sismeiro ◽

Hugo Varet ◽

...

Keyword(s):

Sucrose Gradient ◽

Gradient Analysis ◽

Cell Formation ◽

Fold Increase ◽

Growth Conditions ◽

Lag Phase ◽

Bacterial Signaling ◽

Tryptophan Degradation ◽

70S Ribosome ◽

Persistent Cell

AbstractIndole is a small molecule derived from tryptophan degradation and proposed to be involved in bacterial signaling. We find that indole secretion is induced by sublethal tobramycin concentrations and increases persistence to aminoglycosides in V. cholerae. Indole transcriptomics showed strongly increased expression of raiA, a ribosome associated factor. Deletion of raiA abolishes the appearance of indole dependent persisters to aminoglycosides, while its overexpression leads to 100-fold increase of persisters, and a reduction in lag phase, evocative of increased active 70S ribosome content, which was confirmed by sucrose gradient analysis. We propose that, under stress conditions, inactive 70S ribosomes are associated with RaiA to be stored and rapidly reactivated when growth conditions become favorable again, in a mechanism different than ribosome hibernation. Our results point to an active process of persistent cell formation, through ribosome protection during translational stress and relief upon antibiotic removal. Translation is a universal process, and these results could help elucidate a mechanism of persistence formation in a controlled, thus inducible way.

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