Bacterial vampirism mediated through taxis to serum

Glenn, Siena J.; Gentry-Lear, Zealon; Shavlik, Michael; Harms, Michael J.; Asaki, Thomas J.; Baylink, Arden

doi:10.1101/2023.07.07.548164

Cited by 2 publications

(14 citation statements)

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“…3H), and found that the tsr mutant is unable to respond to either effector. Since our earlier work demonstrated that the tsr strain retains chemotaxis to other stimuli 9 we conclude that Tsr is responsible for indole chemorepulsion.…”

Section: Resultsmentioning

confidence: 54%

“…In this assay, a constant flow of approximately 300 femtoliters per minute is applied to inject the effector through a glass microcapillary 0.5 µm in diameter; chemoattraction is observed as an influx of cells into the field of view over time and congregation near the source, and chemorepulsion is observed as decreasing cells over time and avoidance of the central effector source (Fig. 1C-E) 9 .…”

Section: Resultsmentioning

confidence: 99%

“…CIRA was performed as described previously 9 . Briefly, an Eppendorf Femtotip 2 microcapillary containing the treatment of interest was lowered into a pond of 50 µl of motile cells using a Sutter micromanipulator.…”

Section: Chemosensory Injection Rig Assay (Cira)mentioning

confidence: 99%

“…The chemotaxis systems of many host-associated bacteria, both native commensal and pathogenic species, have been shown to be important for colonization and survival within the host gut 1,4 . Chemotaxis enables motile bacteria to rapidly relocate based on novel sources of effector stimuli and to exert precise control of colonization at the micron-level scale [9][10][11][12] . These abilities translate into growth advantages during initial and long-term colonization because they allow bacteria to adapt to the dynamic circumstances within the gut, which changes frequently in terms of nutrient content, fluidic flow, and microbial competition 1,13,14 .…”

Section: Introductionmentioning

confidence: 99%

“…One example is the chemoreceptor taxis to serine and repellents (Tsr), which we have shown to be widely distributed among bacterial colonizers of the gut, especially Enterobacteriaceae (Fig. 1A) 1,9 .…”

Section: Introductionmentioning

confidence: 99%

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Navigating contradictions: Salmonella Typhimurium chemotactic responses to conflicting effector stimuli

Franco,

Gentry-Lear,

Shavlik

et al. 2024

Preprint

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Many bacteria that colonize the guts of animals use chemotaxis to direct swimming motility and select sites for colonization based on sources of effectors derived from the host, diet, and microbial competitors of the local environ. The complex ecosystem of the gastrointestinal tract contains mixtures of chemoattractants and chemorepellents, but it remains poorly understood how swimming bacteria navigate conflicting signals. The enteric pathogen Salmonella Typhimurium possesses Tsr, a chemoreceptor protein that directs both chemoattraction and chemorepulsion responses, which we employed as a model to study chemotaxis in the presence of conflicting effector stimuli. We investigated how S. Typhimurium responds to human fecal matter, an effector source in the enteric lumen that contains high concentrations of indole, a bacteriostatic chemorepellent produced by the native commensals of the microbiota, and also nutrients such as L-serine, a chemoattractant. The indole concentration in human feces is more than 12-fold the concentration required for half-maximal chemorepulsion, however, we find S. Typhimurium, and various clinical isolates of non-typhoidal S. enterica serovars, are strongly attracted to liquid fecal matter. We further investigated the chemotactic responses of S. Typhimurium to titrations of indole and L-serine and revealed that chemorepulsion to indole is overridden in the presence of excess L-serine. We capture the inversion of these two opposing taxis behaviors in a phenomenon we define as "chemohalation" in which the bacteria organize into a halo around the treatment source with an interior zone of avoidance, which represents a compromise between chemoattraction and chemorepulsion. Growth analyses reveal that the chemotactic responses to these opposing effectors align chemoattraction and chemorepulsion with the relative growth of the bacteria in culture. Hence, our study supports the view that evolution has finely tuned chemotaxis to assess environmental habitability by evaluating the tradeoffs in bacterial growth based on the local combination of effectors.

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Section: Resultsmentioning

confidence: 54%

Section: Resultsmentioning

confidence: 99%

Section: Chemosensory Injection Rig Assay (Cira)mentioning

confidence: 99%