The B12 receptor BtuB alters the membrane integrity of Caulobacter crescentus

Menikpurage, Inoka P.; Barraza, Daniela Estefanía; Meléndez, Ady B.; Strebe, Sierra; Mera, Paola E.

doi:10.1099/mic.0.000753

Cited by 10 publications

(10 citation statements)

References 71 publications

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“…This increase was always ChvIG dependent, as it was never seen in the Δ chvIG-hprK strain. Finally, we investigated the effect of inducing outer membrane stress on P chvR activity with the detergent sodium deoxycholate ( 16 ). This condition increased P chvR activity in all strains, with a significantly larger increase seen in the Δ tipN strain than in the WT ( Fig.…”

Section: Resultsmentioning

confidence: 99%

“…The Caulobacter genome encodes 105 putative signal transduction proteins and 65 TonB-dependent receptors ( 12 ), which are potentially important for environmental sensing and nutrient uptake, respectively. The TonB-dependent receptors have not been systematically characterized, but individual members of this family have been found to be specific receptors for vitamins or metal ions ( 13 – 16 ) or to be transcriptionally upregulated under conditions of carbon or nitrogen starvation ( 17 ). Regulation of TonB-dependent receptors, as for outer membrane proteins in general, is often posttranscriptionally controlled by small noncoding RNAs (sRNAs) ( 18 ).…”

Section: Introductionmentioning

confidence: 99%

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Loss of Bacterial Cell Pole Stabilization in Caulobacter crescentus Sensitizes to Outer Membrane Stress and Peptidoglycan-Directed Antibiotics

Vallet

Hansen

Bistrup

et al. 2020

mBio

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Rod-shaped bacteria frequently localize proteins to one or both cell poles in order to regulate processes such as chromosome replication or polar organelle development. However, the roles of polar factors in responses to extracellular stimuli have been generally unexplored. We employed chemical-genetic screening to probe the interaction between one such factor from Caulobacter crescentus, TipN, and extracellular stress and found that TipN is required for normal resistance of cell envelope-directed antibiotics, including vancomycin which does not normally inhibit growth of Gram-negative bacteria. Forward genetic screening for suppressors of vancomycin sensitivity in the absence of TipN revealed the TonB-dependent receptor ChvT as the mediator of vancomycin sensitivity. Loss of ChvT improved resistance to vancomycin and cefixime in the otherwise sensitive ΔtipN strain. The activity of the two-component system regulating ChvT (ChvIG) was increased in ΔtipN cells relative to the wild type under some, but not all, cell wall stress conditions that this strain was sensitized to, in particular cefixime and detergent exposure. Together, these results indicate that TipN contributes to cell envelope stress resistance in addition to its roles in intracellular development, and its loss influences signaling through the ChvIG two-component system which has been co-opted as a sensor of cell wall stress in Caulobacter. IMPORTANCE Maintenance of an intact cell envelope is essential for free-living bacteria to protect themselves against their environment. In the case of rod-shaped bacteria, the poles of the cell are potential weak points in the cell envelope due to the high curvature of the layers and the need to break and reform the cell envelope at the division plane as the cells divide. We have found that TipN, a factor required for correct division and cell pole development in Caulobacter crescentus, is also needed for maintaining normal levels of resistance to cell wall-targeting antibiotics such as vancomycin and cefixime, which interfere with peptidoglycan synthesis. Since TipN is normally located at the poles of the cell and at the division plane just before cells complete division, our results suggest that it is involved in stabilization of these weak points of the cell envelope as well as its other roles inside the cell.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Loss of Bacterial Cell Pole Stabilization in Caulobacter crescentus Sensitizes to Outer Membrane Stress and Peptidoglycan-Directed Antibiotics

Vallet

Hansen

Bistrup

et al. 2020

mBio

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“…This increase was always ChvIG-dependent, as it was never seen in the Δ chvIG-hprK strain. Finally, we investigated the effect of inducing non-specific cell envelope stress on P chvR activity with sodium deoxycholate, a detergent which destabilises the outer membrane [16]. This condition increased P chvR activity in all strains, with a significantly larger increase seen in the Δ tipN strain compared to WT (Fig 6G).…”

Section: Resultsmentioning

confidence: 99%

“…Sodium deoxycholate resistance was assayed as described in [16]. Cultures of strains to be tested were diluted from saturated overnight cultures to an OD600 of 0.2 in PYE with and without sodium deoxycholate at 0.6 mg/ml and incubated at 30°C for 24 hours.…”

Section: Methodsmentioning

confidence: 99%

“…Caulobacter encodes 105 putative signal transduction proteins and 65 TonB-dependent receptors in its genome [12], which are potentially important for environmental sensing and nutrient uptake, respectively. The TonB-dependent receptors have not been systematically characterized, but individual members of this family have been found to be specific receptors for vitamins or metal ions [13–16] or to be transcriptionally upregulated under conditions of carbon or nitrogen starvation [17]. Regulation of TonB-dependent receptors, as for outer membrane proteins in general, is often post-transcriptionally controlled by small noncoding RNAs (sRNAs) [18].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Loss of Bacterial Cell Pole Stabilization inCaulobacter crescentusSensitizes to Outer Membrane Stress and Peptidoglycan-Directed Antibiotics

Vallet

Hansen

Bistrup

et al. 2019

Preprint

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AbstractRod-shaped bacteria frequently localise proteins to one or both cell poles in order to regulate processes such as chromosome replication or polar organelle development. However, the role of such polar factors in responses to extracellular stimuli has been generally unexplored. We employed chemical-genetic screening to probe the interaction between one such factor from Caulobacter crescentus, TipN, and extracellular stress and found that TipN is required for normal tolerance of cell envelope-directed antibiotics, including vancomycin that does not normally inhibit growth of Gram-negative bacteria. Forward genetic screening for suppressors of vancomycin sensitivity in the absence of TipN revealed the TonB-dependent receptor ChvT as the mediator of vancomycin tolerance. Loss of ChvT improved resistance to vancomycin and cefixime in the otherwise sensitive ΔtipN strain. The activity of the two-component system regulating ChvT (ChvIG) was increased in ΔtipN cells relative to wild type under some, but not all, cell wall stress conditions that this strain was sensitised to, in particular cefixime and detergent exposure. Together, these results indicate that the ChvIG two-component system has been co-opted as a sensor of cell wall stress and that TipN can influence cell envelope stability and ChvIG-mediated signaling in addition to its roles in intracellular development.Author summaryMaintenance of an intact cell envelope is essential for free-living bacteria to survive harsh conditions they may encounter in their environment. In the case of rod-shaped bacteria, the poles of the cell are potential weak points in the cell envelope due to the high curvature of the layers and the need to break and re-form parts of the cell envelope at the division plane in order to form new poles as the cells replicate and divide. We have found that TipN, a factor required for correct division and cell pole development in the rod-shaped bacterium, Caulobacter crescentus, is also needed for maintaining normal levels of resistance to cell wall-targeting antibiotics such as vancomycin and cefixime, which interfere with peptidoglycan synthesis. We also identified an outer membrane receptor, ChvT, that was responsible for allowing vancomycin access to the cells and found that the two-component system that negatively regulates ChvT production was activated by various kinds of cell wall stress. Presence or absence of TipN influenced how active this system was in the presence of cefixime or of the membrane-disrupting detergent sodium deoxycholate. Since TipN is normally located at the poles of the cell and at the division plane just before cells complete division, our results suggest that it is involved in stabilisation of these weak points of the cell envelope as well as its other roles inside the cell.

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