Mechanical Genomic Studies Reveal the Role of
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            -Alanine Metabolism in Pseudomonas aeruginosa Cell Stiffness

Trivedi, Rishi R.; Crooks, John A.; Auer, George K.; Pendry, Joel; Foik, Ilona P.; Siryaporn, Albert; Abbott, Nicholas L.; Gitai, Zemer; Weibel, Douglas B.

doi:10.1128/mbio.01340-18

Cited by 26 publications

(22 citation statements)

References 75 publications

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“…Recent work has shown that bacterial cell stiffness is tightly regulated by many interacting genes (Trivedi et al, 2018). This is consistent with the idea that appropriate deformation of the cell envelope and embedded envelope proteins, leading to appropriate mechanosensing and response, could provide a selective advantage for bacteria under evolutionary pressuree.g.…”

Section: Box 1 Regulation Of the Mechanics Of Bacteriasupporting

confidence: 78%

Bacterial mechanosensing: the force will be with you, always

Gordon

Wang

2019

Journal of Cell Science

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Whether bacteria are in the planktonic state, free-swimming or freefloating in liquid, or in the biofilm state, sessile on surfaces, they are always subject to mechanical forces. The long, successful evolutionary history of bacteria implies that they are capable of adapting to varied mechanical forces, and probably even actively respond to mechanical cues in their changing environments. However, the sensing of mechanical cues by bacteria, or bacterial mechanosensing, has been under-investigated. This leaves the mechanisms underlying how bacteria perceive and respond to mechanical cues largely unknown. In this Review, we first examine the surface-associated behavior of bacteria, outline the clear evidence for bacterial mechanosensing and summarize the role of flagella, type-IV pili, and envelope proteins as potential mechanosensors, before presenting indirect evidence for mechanosensing in bacteria. The general themes underlying bacterial mechanosensing that we highlight here may provide a framework for future research.

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Section: Box 1 Regulation Of the Mechanics Of Bacteriasupporting

confidence: 78%

Bacterial mechanosensing: the force will be with you, always

Gordon

Wang

2019

Journal of Cell Science

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“…A recent study revealed the connection between changes in the biochemical regulation of D-Ala-D-Ala and Pseudomonas aeruginosa cell stiffness in cells in which this biochemical machinery is altered (32). As our paper and the paper on P. aeruginosa demonstrate (32), This current study and the P. aeruginosa paper (32) demonstrate that it is still difficult to quantitatively understand the scaling between the magnitude of the biochemical changes in cells and the changes in cell stiffness. The range of techniques now available for quantitatively measuring single cell stiffness will enable the development of this relationship.…”

Section: Discussionmentioning

confidence: 99%

Bacterial swarming reducesProteus mirabilisandVibrio parahaemolyticuscell stiffness and increases β-lactam susceptibility

Auer¹,

Oliver

Rajendram

et al. 2018

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1Swarmer cells of the gram-negative uropathogenic bacteria Proteus mirabilis and Vibrio 2 parahaemolyticus become long (>10-100 µm) and multinucleate during their growth and 3 motility on polymer surfaces. We demonstrate increasing cell length is accompanied by 4 a large increase in flexibility. Using a microfluidic assay to measure single-cell 5 mechanics, we identified large differences in swarmer cell stiffness of (bending rigidity 6 of P. mirabilis, 9.6 x 10 -22 N m 2 ; V. parahaemolyticus, 9.7 x 10 -23 N m 2 ) compared to 7 vegetative cells (1.4 x 10 -20 N m 2 and 3.2 x 10 -22 N m 2 , respectively). The reduction in 8 bending rigidity (~3-24 fold) was accompanied by a decrease in the average 9 polysaccharide strand length of the peptidoglycan layer of the cell wall from 28-30 to 10 19-22 disaccharides. Atomic force microscopy revealed a reduction in P. mirabilis 11 peptidoglycan thickness from 1.5 nm (vegetative) to 1.0 nm (swarmer) and electron 12 cryotomography indicated changes in swarmer cell wall morphology. P. mirabilis and V. 13 parahaemolyticus swarmer cells became increasingly sensitive to osmotic pressure and 14 susceptible to cell wall-modifying antibiotics (compared to vegetative cells)-they were 15 ~30% more likely to die after 3 h of treatment with minimum inhibitory concentrations 16 of the β-lactams cephalexin and penicillin G. The adaptive cost of swarming is offset by 17 the increase in cell susceptibility to physical and chemical changes in their environment, 18 thereby suggesting the development of new chemotherapies for bacteria that leverage 19 swarming for the colonization of hosts and survival. 20 Importance 1Proteus mirabilis and Vibrio parahaemolyticus are bacteria that infect humans. To adapt to 2 environmental changes, these bacteria alter their cell morphology and move collectively 3 to access new sources of nutrients in a process referred to as 'swarming'. We found that 4 a change in the composition and thickness of the peptidoglycan layer of the cell wall 5 makes swarmer cells of P. mirabilis and V. parahaemolyticus more flexible (i.e., reduced 6 cell stiffness) and increases their sensitivity to osmotic pressure and cell-wall targeting 7 antibiotics (e.g., β-lactams). These results highlight the importance of assessing the 8 extracellular environment in determining antibiotic doses and the use of β-lactams 9 antibiotics for treating infections caused by swarmer cells of P. mirabilis and V. 10 parahaemolyticus. 11 12 13 14 15 16 17 18 19 20

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“…Bacteria constitute a vibrant playground for studies of physical form based on their diverse shapes, on the selective advantages that these shapes confer ( 4 ), and on their genetic tractability for systems-level interrogation. In their recent article in mBio , Trivedi et al ( 5 ) utilize a high-throughput approach to identify a set of proteins that influence the ability of the Gram-negative pathogen Pseudomonas aeruginosa to grow while embedded in agarose, a signature of altered cellular stiffness. The authors characterize a novel feedback mechanism tied to free levels of the amino acid d -alanine; an increase of d -alanine triggers changes to the cell wall through the transcriptional regulation of peptidoglycan transpeptidases ( 5 ).…”

Section: Commentarymentioning

confidence: 99%

“…Moreover, virulence induction in P. aeruginosa depends on the mechanical properties of the surface to which cells are attached ( 10 ). With these factors as motivation, Trivedi et al applied the GRABS methodology to generate a mechanical genomics map of P. aeruginosa using a transposon library of 5,693 mutants ( 5 ). They identified dozens of mutants with decreased growth rates specific to agarose, potentially signifying a decrease in cell stiffness.…”

Section: Commentarymentioning

confidence: 99%

“…Through a series of biochemical and biophysical experiments, Trivedi et al demonstrated that higher d -alanine levels result in transcriptional regulation of cell wall synthesis and a change in cell wall composition ( 5 ). First, when dadA cells were grown in media with increasing concentrations of d -alanine, their GRABS score became even more negative, suggesting a further reduction in stiffness.…”

Section: Commentarymentioning

confidence: 99%

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