Inducer exclusion, by itself, cannot account for the glucose-mediated lac repression of Escherichia coli

Aggarwal, Ritesh Kumar; Narang, Atul

doi:10.1016/j.bpj.2022.01.016

Cited by 5 publications

(3 citation statements)

References 38 publications

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“…The lacZYA promoter of pAM34 contains the binding site for the complex of the CAP cyclic‐AMP activator protein with cyclic‐AMP. The low cyclic‐AMP levels in cultures grown with glucose (the prevalent carbon source used in minimal media) shut down the lacZYA promoter even in the presence of IPTG (Aggarwal & Narang, 2022). To cope with the need to avoid glucose using the IPTG‐dependent vectors, the lac regulatory system of pAM34 was replaced with the well‐understood transposon Tn 10 tetracycline (Tet) regulatory system (Figure 2) (Cronan, 2016).…”

Section: Tetracycline‐dependent Replication Plasmidsmentioning

confidence: 99%

Two neglected but valuable genetic tools for Escherichia coli and other bacteria: In vivo cosmid packaging and inducible plasmid replication

Cronan

2023

Molecular Microbiology

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In physiology and synthetic biology, it can be advantageous to introduce a gene into a naive bacterial host under conditions in which all cells receive the gene and remain fully functional. This cannot be done by the usual chemical transformation and electroporation methods due to low efficiency and cell death, respectively. However, in vivo packaging of plasmids (called cosmids) that contain the 223 bp cos site of phage λ results in phage particles that contain concatemers of the cosmid that can be transduced into all cells of a culture. An historical shortcoming of in vivo packaging of cosmids was inefficient packaging and contamination of the particles containing cosmid DNA with a great excess of infectious λ phage. Manipulation of the packaging phage and the host has eliminated these shortcomings resulting in particles that contain only cosmid DNA. Plasmids have the drawback that they can be difficult to remove from cells. Plasmids with conditional replication provide a means to “cure” plasmids from cells. The prevalent conditional replication plasmids are temperature‐sensitive plasmids, which are cured at high growth temperature. However, inducible replication plasmids are in some cases more useful, especially since this approach has been applied to plasmids having diverse replication and compatibility properties.

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Section: Tetracycline‐dependent Replication Plasmidsmentioning

confidence: 99%

Two neglected but valuable genetic tools for Escherichia coli and other bacteria: In vivo cosmid packaging and inducible plasmid replication

Cronan

2023

Molecular Microbiology

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“…The uptake of glucose inhibiting the ability of lactose permease to transport lactose into the cell is known as inducer exclusion [7]. The uptake of glucose by the phosphotransferase system (PTS) is accompanied by the formation of the de-phosphorylated enzyme EIIA Glc , which inactivates lactose permease by binding to it [8].…”

Section: Introductionmentioning

confidence: 99%

Emergent lag phase in flux-regulation models of diauxie

Bate

Amekan

Pushkin

et al. 2023

Preprint

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Lag phase is observed in bacterial growth during a sudden change in conditions: growth is inhibited whilst cells adapt to the environment. Bi-phasic, or diauxic growth is commonly exhibited by many species. In the presence of two sugars, cells initially grow by consuming the preferred sugar then undergo a lag phase before resuming growth on the second. Biomass increase is characterised by a diauxic growth curve: exponential growth followed by a period of no growth before a second exponential growth. Recent literature lacks a complete dynamic description, artificially modelling lag phase and employing non-physical representations of precursor pools. Here, we focus on glucose-lactose diauxie ofEscherichia coliformulating a rational mechanistic model based on flux-regulation/proteome partitioning with a finite precursor pool that reveals core mechanisms in a compact form. Unlike earlier systems, the characteristic dynamics emerge as part of the solution, including the lag phase, and results accurately reproduce experiments. We show that for a single strain ofE. coli, diauxic growth yields mathematically optimised growth rates. However, intriguingly, for two competing strains diauxic growth is not always the best strategy. Our description can be generalised to model multiple different microorganisms and investigate competition between species/strains.

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“…The uptake of glucose inhibiting the ability of lactose permease to transport lactose into the cell is known as inducer exclusion (Aggarwal and Narang 2022 ). The uptake of glucose by the phosphotransferase system (PTS) is accompanied by the formation of the de-phosphorylated enzyme EIIA , which inactivates lactose permease by binding to it (Hogema et al.…”

Section: Introductionmentioning

confidence: 99%

Emergent Lag Phase in Flux-Regulation Models of Bacterial Growth

Bate,

Amekan,

Pushkin

et al. 2023

Bull Math Biol

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Lag phase is observed in bacterial growth during a sudden change in conditions: growth is inhibited whilst cells adapt to the environment. Bi-phasic, or diauxic growth is commonly exhibited by many species. In the presence of two sugars, cells initially grow by consuming the preferred sugar then undergo a lag phase before resuming growth on the second. Biomass increase is characterised by a diauxic growth curve: exponential growth followed by a period of no growth before a second exponential growth. Recent literature lacks a complete dynamic description, artificially modelling lag phase and employing non-physical representations of precursor pools. Here, we formulate a rational mechanistic model based on flux-regulation/proteome partitioning with a finite precursor pool that reveals core mechanisms in a compact form. Unlike earlier systems, the characteristic dynamics emerge as part of the solution, including the lag phase. Focussing on growth of Escherichia coli on a glucose–lactose mixture we show results accurately reproduce experiments. We show that for a single strain of E. coli, diauxic growth leads to optimised biomass yields. However, intriguingly, for two competing strains diauxic growth is not always the best strategy. Our description can be generalised to model multiple different microorganisms and investigate competition between species/strains.

show abstract

Inducer exclusion, by itself, cannot account for the glucose-mediated lac repression of Escherichia coli

Cited by 5 publications

References 38 publications

Two neglected but valuable genetic tools for Escherichia coli and other bacteria: In vivo cosmid packaging and inducible plasmid replication

Two neglected but valuable genetic tools for Escherichia coli and other bacteria: In vivo cosmid packaging and inducible plasmid replication

Emergent lag phase in flux-regulation models of diauxie

Emergent Lag Phase in Flux-Regulation Models of Bacterial Growth

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