Analysis of the role of betL in contributing to the growth and survival of Listeria monocytogenes LO28

Sleator, Roy D.; Gahan, Cormac G. M.; O'driscoll, B.; Hill, Colin

doi:10.1016/s0168-1605(00)00316-0

Cited by 55 publications

(59 citation statements)

References 21 publications

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“…1). Exposure of LO28⌬G to salt stress resulted in an increase in transcript levels similar to that observed previously (25). However, no transcriptional up-regulation was observed for LO28n⌬BG(pCPL17), proving that salt-induced transcriptional up-regulation had been removed.…”

Section: Resultssupporting

confidence: 83%

“…For example, transporters BetP and EctP of Corynebacterium glutamicum, both of which are BetL sequence homologues, can be osmotically activated (18). Previously, we demonstrated that betL is osmoregulated at the transcriptional level (25). Using the nisin-controlled expression (NICE) system for salinity-independent gene expression (3), we now demonstrate that BetL is itself activated in response to changes in salinity.…”

mentioning

confidence: 74%

“…RNA isolation and reverse transcription-PCR (RT-PCR) were carried out as previously described (25). RNA was isolated from overnight cultures following nisin induction or imposition of a salt stress.…”

Section: Methodsmentioning

confidence: 99%

“…For induction with nisin, cultures were grown to an OD 600 of 0.2 and either induced with a 0.1% concentration of the supernatant from an overnight culture of the nisin-producing strain Lactococcus lactis NZ9700 or preinduced with 4.5 g of nisin powder/ml for 1 h and then induced with 45 g of nisin powder/ml (a concentration high enough to induce transcription, yet low enough to ensure no difference in the nisin sensitivities of the two strains [data not shown]) for 30 min before RNA was isolated. Following RT, primers XbaIKO and EcoRIKO, described previously (25), were used to amplify the resulting cDNA. In all cases, control PCR primers were used to confirm the complete removal of DNA from non-reverse-transcribed RNA preparations and subsequently following the RT reaction to ensure that levels of cDNA for samples that were to be compared were equal.…”

Section: Methodsmentioning

confidence: 99%

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Transcriptional Regulation and PosttranslationalActivity of the Betaine Transporter BetL in Listeriamonocytogenes Are Controlled by EnvironmentalSalinity

2003

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While the genetic elements contributing to the salinity tolerance of Listeria monocytogenes have been well characterized, the regulatory signals and responses (genetic and/or biochemical) that govern these mechanisms have yet to be elucidated. Encoded by betL, the first genetic element to be linked to listerial osmotolerance, the secondary betaine uptake system BetL is a member of the betaine-carnitine-choline transporter family. Preceded by consensus A -and B -dependent promoter sites, betL is constitutively expressed and transcriptionally up-regulated in response to salt stress. The nisin-controlled expression system was used to achieve salinity-independent, controlled betL expression in Listeria. In the absence of NaCl-activated transcriptional control, BetL activity was found to be a function of environmental salinity, showing optimal activity in buffer supplemented with 1 to 2% NaCl (osmolality, 417 to 719 mosmol/kg). In addition, BetL was activated rapidly (half-life, 2 min) in response to an osmotic upshift imposed by adding 2% NaCl to 50 mM potassium phosphate buffer.The ubiquitous food-borne pathogen Listeria monocytogenes is highly adapted to life in challenging environments (10). The ability of the organism to survive, and indeed thrive, at elevated osmolarities and reduced temperatures is attributed mainly to the accumulation of osmo-and cryoprotective compounds termed osmolytes, or compatible solutes (13, 27). Indeed, recent evidence suggests that osmolyte uptake in L. monocytogenes is linked not only to the ability of the organism to grow and survive in foods but also to the ability of the organism to cause infection (26, 29). The preferred compatible solute for the majority of bacteria, and the most effective osmolyte in L. monocytogenes, is the trimethyl ammonium compound glycine betaine. Present at relatively high concentrations in foods of plant origin (22), betaine has been shown to stimulate the growth of L. monocytogenes between 0.3 and 0.7 M NaCl, resulting in a 2.1-fold increase in the growth rate at 0.7 M NaCl (1) and a 1.8-fold increase at 4°C (13).Although betaine was previously believed to be accumulated by a single transporter (20), recent genetic analysis revealed that L. monocytogenes takes up betaine via more than one system (28). The principal transporters include the multicomponent, ATP-dependent GbuABC system (12) and the ionmotive-force-dependent secondary transporter BetL (24). Each system exhibits distinct substrate specificities and kinetic parameters and thus is presumably optimized for maximal effects in diverse ecological niches (29).Since the osmolyte transport systems of L. monocytogenes have been cataloged (28), the next major challenge is to elucidate the individual contribution of each system to the overall salt stress response. Determining how and when individual systems are activated, to what extent, and in response to which signal(s) (internal or external salinity and/or osmolality, turgor pressure, or related parameters, such as membrane tension) will ultimately ...

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Section: Resultssupporting

confidence: 83%

mentioning

confidence: 74%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Transcriptional Regulation and PosttranslationalActivity of the Betaine Transporter BetL in Listeriamonocytogenes Are Controlled by EnvironmentalSalinity

2003

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“…The BetL protein of strain LO28 is a betaine transporter, belonging to a Na ϩ -dependent symport family of secondary transporters (26). Deletion of betL in L. monocytogenes results in slow growth in media with elevated osmolarity but no significant effect on virulence (27). Gbu, encoded by the gbuABC operon, is an ATP-dependent transporter belonging to the ATP binding cassette (ABC) superfamily of transporters, and it is homologous to OpuA in Bacillus subtilis and ProU in Escherichia coli (19).…”

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confidence: 99%

Regulation of Transcription of Compatible Solute Transporters by the General Stress Sigma Factor, σ^B, inListeria monocytogenes

2004

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Listeria monocytogenes is well known for its durable physiological characteristics, which allow the organism to grow at low temperature and pH and high osmolarity. Growth under high osmolarity depends on the accumulation of compatible solutes, among which glycine betaine and carnitine are the preferred solutes for this organism. Three different transport systems, Gbu, BetL, and OpuC, have been identified in L. monocytogenes which serve to scavenge the preferred compatible solutes. The general stress response regulator B has been shown to play an important role in osmotic adaptation in L. monocytogenes, presumably by directing transcription from one or more of the solute transport genes. In the studies presented here, we have used primer extension analyses to identify the promoter elements responsible for transcription of the opuC, gbuA, and betL genes. All three genes are osmotically inducible to some degree. betL is transcribed from a Bindependent promoter, while gbuA is transcribed from dual promoters, one of which is B dependent. opuC is transcribed exclusively from a B -dependent promoter. The betL promoter is similar in sequence to the B -independent gbuAP1 promoter. Kinetic analysis of transcript accumulation after osmotic upshift demonstrated that B -dependent transcripts from gbuAP2 and sigB accumulate for an extended period after upshift, suggesting that B activity may provide a mechanism for sustained high-level expression during osmotic challenge. In contrast to osmotic upshift, expression from the B -dependent opuC and gbuAP2 promoters after temperature upshift and ethanol stress was minimal, suggesting that additional mechanisms may also participate in regulating transcription from these B -dependent promoters.

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Modulation of gut‐microbiota through probiotics and dietary interventions to improve host health

Dasriya,

Samtiya,

Ranveer

et al. 2024

J Sci Food Agric

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Dietary patterns play an important role in regards to the modulation and control of the gut microbiome composition and function. The interaction between diet and microbiota plays an important role in order to maintain intestinal homeostasis, which ultimately afftect the host's health. Diet directly impacts the microbes that inhabit the gastrointestinal tract (GIT), which then contributes to the production of secondary metabolites, such as short‐chain fatty acids, neurotransmitters, and antimicrobial peptides. Dietary consumption with genetically modified probiotics can be the best vaccine delivery vector and protect cells from various illnesses. A holistic approach to disease prevention, treatment, and management take these intrinsically linked diet‐microbes, microbe‐microbe interactions, and microbe‐host interactions into account. Dietary components, such as fibre can modulate beneficial gut microbiota, and they have resulting ameliorative effects against metabolic disorders. Medical interventions, such as antibiotic drugs can conversely have detrimental effects on gut microbiota by disputing the balance between Bacteroides and firmicute, which contribute to continuing disease states. We summarise the known effects of various dietary components, such as fibres, carbohydrates, fatty acids, vitamins, minerals, proteins, phenolic acids, and antibiotics on the composition of the gut microbiota in this paper in addition to the beneficial effect of genetically modified probiotics and consequentially its role in regards to shaping human health.This article is protected by copyright. All rights reserved.

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Analysis of the role of betL in contributing to the growth and survival of Listeria monocytogenes LO28

Cited by 55 publications

References 21 publications

Transcriptional Regulation and PosttranslationalActivity of the Betaine Transporter BetL in Listeriamonocytogenes Are Controlled by EnvironmentalSalinity

Transcriptional Regulation and PosttranslationalActivity of the Betaine Transporter BetL in Listeriamonocytogenes Are Controlled by EnvironmentalSalinity

Regulation of Transcription of Compatible Solute Transporters by the General Stress Sigma Factor, σ^B, inListeria monocytogenes

Modulation of gut‐microbiota through probiotics and dietary interventions to improve host health

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Analysis of the role of betL in contributing to the growth and survival of Listeria monocytogenes LO28

Cited by 55 publications

References 21 publications

Transcriptional Regulation and PosttranslationalActivity of the Betaine Transporter BetL in Listeriamonocytogenes Are Controlled by EnvironmentalSalinity

Transcriptional Regulation and PosttranslationalActivity of the Betaine Transporter BetL in Listeriamonocytogenes Are Controlled by EnvironmentalSalinity

Regulation of Transcription of Compatible Solute Transporters by the General Stress Sigma Factor, σB, inListeria monocytogenes

Modulation of gut‐microbiota through probiotics and dietary interventions to improve host health

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Regulation of Transcription of Compatible Solute Transporters by the General Stress Sigma Factor, σ^B, inListeria monocytogenes