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Abstract Microbial cells must continually adapt their physiology in the face of changing environmental conditions. Archaea living in extreme conditions, such as saturated salinity, represent important examples of such resilience. The model salt‐loving organismHaloferax volcaniiexhibits remarkable plasticity in its morphology, biofilm formation, and motility in response to variations in nutrients and cell density. However, the mechanisms regulating these lifestyle transitions remain unclear. In prior research, we showed that the transcriptional regulator, TrmB, maintains the rod shape in the related speciesHalobacterium salinarumby activating the expression of enzyme‐coding genes in the gluconeogenesis metabolic pathway. InHbt. salinarum, TrmB‐dependent production of glucose moieties is required for cell surface glycoprotein biogenesis. Here, we use a combination of genetics and quantitative phenotyping assays to demonstrate that TrmB is essential for growth under gluconeogenic conditions inHfx. volcanii. The ∆trmBstrain rapidly accumulated suppressor mutations in a gene encoding a novel transcriptional regulator, which we nametrmBsuppressor, or TbsP (a.k.a. “tablespoon”). TbsP is required for adhesion to abiotic surfaces (i.e., biofilm formation) and maintains wild‐type cell morphology and motility. We use functional genomics and promoter fusion assays to characterize the regulons controlled by each of TrmB and TbsP, including joint regulation of the glucose‐dependent transcription ofgapII, which encodes an important gluconeogenic enzyme. We conclude that TrmB and TbsP coregulate gluconeogenesis, with downstream impacts on lifestyle transitions in response to nutrients inHfx. volcanii.
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Plasmid‐encoded protein attenuates Escherichia coli swimming velocity and cell growth, not reprogrammed regulatory functions
In addition to engineering new pathways for synthesis, synthetic biologists rewire cells to carry out “programmable” functions, an example being the creation of wound‐healing probiotics. Engineering regulatory circuits and synthetic machinery, however, can be deleterious to cell function, particularly if the “metabolic burden” is significant. Here, a synthetic regulatory circuit previously constructed to directEscherichiacolito swim toward hydrogen peroxide, a signal of wound generation, was shown to work even with coexpression of antibiotic resistance genes and genes associated with lactose utilization. We found, however, that cotransformation with a second vector constitutively expressing GFP (as a marker) and additionally conferring resistance to kanamycin and tetracycline resulted in slower velocity (Δ~6 μm/s) and dramatically reduced growth rate (Δ > 50%). The additional vector did not, however, alter the run‐and‐tumble ratio or directional characteristics of H2O2–dependent motility. The main impact of this additional burden was limited to slowing cell velocity and growth, suggesting that reprogrammed cell motility by minimally altering native regulatory circuits can be maintained even when extraneous burden is placed on the host cell. © 2019 American Institute of Chemical EngineersBiotechnol. Prog., 35: e2778, 2019.
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- PAR ID:
- 10461250
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Biotechnology Progress
- Volume:
- 35
- Issue:
- 3
- ISSN:
- 8756-7938
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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