The Production of Listeriolysin O and Subsequent Intracellular Infections by Listeria monocytogenes Are Regulated by Exogenous Short Chain Fatty Acid Mixtures

Listeria monocytogenes is a foodborne pathogen capable of secreting listeriolysin O (LLO), a pore-forming toxin encoded by the hly gene. While the functions of LLO have been studied extensively, how the production of LLO is modulated by the intestinal environment, devoid of oxygen and enriched in short chain fatty acids (SCFAs), is not completely understood. Using L. monocytogenes strain 10403s, we found that hly transcription was moderately decreased by aerobic SCFA exposures but significantly increased by anaerobic SCFA exposures. Moreover, aerobic, but not anaerobic, exposure to low levels of SCFAs resulted in a significantly higher LLO activity. These results demonstrated that transcriptional and post-transcriptional regulations of LLO production were separately modulated by SCFAs and were responsive to oxygen levels. Examining isogenic mutants revealed that PrfA and SigB play a role in regulating LLO production in response to SCFAs. Effects of SCFAs were also present in the cardiotropic strain 07PF0776 but distinctly different from those in strain 10403s. For both strains, prior exposures to SCFAs altered intracellular infections in Caco-2 and RAW264.7 cells and the plaque sizes in L fibroblasts, a result confirming the ability of L. monocytogenes to adapt to SCFAs in ways that impact its subsequent infection outcomes.

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Short-chain fatty acids activate acetyltransferase p300

10.1101/2021.07.21.453192 ◽

2021 ◽

Author(s):

Sydney Thomas ◽

John Denu

Keyword(s):

Fatty Acids ◽

Histone Deacetylases ◽

Quantitative Proteomics ◽

Short Chain Fatty Acids ◽

Short Chain ◽

Physiological Processes ◽

Low Levels ◽

Underlying Mechanisms ◽

Chain Fatty Acids ◽

Acetyltransferase P300

Short-chain fatty acids (SCFAs) acetate, propionate, and butyrate are produced in large quantities by the gut microbiome and contribute to a wide array of physiological processes. While the underlying mechanisms are largely unknown, many effects of SCFAs have been traced to changes in the cell’s epigenetic state. Here, we systematically investigate how SCFAs alter the epigenome. Using quantitative proteomics of histone modification states, we identified rapid and sustained increases in histone acetylation after addition of butyrate or propionate, but not acetate. While decades of prior observations would have suggested that hyperacetylation induced by SCFAs are attributed to inhibition of histone deacetylases (HDACs), we found that propionate and butyrate instead activate the acetyltransferase p300. Propionate and butyrate are rapidly converted to the corresponding acyl-CoAs which are then used by p300 to catalyze auto-acylation of the autoinhibitory loop, activating the enzyme for histone/protein acetylation. This data challenges the long-held belief that SCFAs mainly regulate chromatin by inhibiting HDACs, and instead reveals a previously unappreciated mechanism of HAT activation that can explain how even low levels of SCFAs alter global chromatin states.

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Stimulating Respiratory Activity Primes Anaerobically Grown Listeria monocytogenes for Subsequent Intracellular Infections

Pathogens ◽

10.3390/pathogens7040096 ◽

2018 ◽

Vol 7 (4) ◽

pp. 96 ◽

Cited By ~ 1

Author(s):

Nathan Wallace ◽

Erica Rinehart ◽

Yvonne Sun

Keyword(s):

Listeria Monocytogenes ◽

Respiratory Activity ◽

Growth Conditions ◽

Growth Defect ◽

Listeriolysin O ◽

Low Oxygen ◽

Intracellular Growth ◽

Aerobic Conditions ◽

Intracellular Infections ◽

Cell Spread

Listeria monocytogenes (L. monocytogenes) is a Gram-positive, enteric pathogen and the causative agent of listeriosis. During transition through the gastrointestinal tract, L. monocytogenes routinely encounters suboxic conditions. However, how the exposure to the low oxygen environment affects subsequent pathogenesis is not completely understood. Our lab previously reported that anaerobically grown L. monocytogenes exhibited an intracellular growth defect in macrophages even though the infection took place under aerobic conditions. This phenotype suggests that prior growth conditions have a prolonged effect on the outcome of subsequent intracellular infection. In this study, to further investigate the mechanisms that contribute to the compromised intracellular growth after anaerobic exposure, we hypothesized that the lack of respiratory activity under anaerobic conditions prevented anaerobically grown L. monocytogenes to establish subsequent intracellular growth under aerobic conditions. To test this hypothesis, respiratory activity in anaerobically grown L. monocytogenes was stimulated by exogenous fumarate and subsequent intracellular pathogenesis was assessed. The results showed that fumarate supplementation significantly increased the respiratory activity of anaerobically grown L. monocytogenes and rescued the subsequent intracellular growth defect, likely through promoting the production of listeriolysin O, phagosomal escape, and cell-cell spread. This study highlights the importance of respiratory activity in L. monocytogenes in modulating the outcome of subsequent intracellular infections.

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Short-chain fatty acids activate acetyltransferase p300

eLife ◽

10.7554/elife.72171 ◽

2021 ◽

Vol 10 ◽

Author(s):

Sydney P Thomas ◽

John M Denu

Keyword(s):

Fatty Acids ◽

Histone Deacetylases ◽

Quantitative Proteomics ◽

Short Chain Fatty Acids ◽

Short Chain ◽

Physiological Processes ◽

Low Levels ◽

Underlying Mechanisms ◽

Chain Fatty Acids ◽

Acetyltransferase P300

Short-chain fatty acids (SCFAs) acetate, propionate, and butyrate are produced in large quantities by the gut microbiome and contribute to a wide array of physiological processes. While the underlying mechanisms are largely unknown, many effects of SCFAs have been traced to changes in the cell’s epigenetic state. Here, we systematically investigate how SCFAs alter the epigenome. Using quantitative proteomics of histone modification states, we identified rapid and sustained increases in histone acetylation after addition of butyrate or propionate, but not acetate. While decades of prior observations would have suggested that hyperacetylation induced by SCFAs are attributed to inhibition of histone deacetylases (HDACs), we found that propionate and butyrate instead activate the acetyltransferase p300. Propionate and butyrate are rapidly converted to the corresponding acyl-CoAs which are then used by p300 to catalyze auto-acylation of the autoinhibitory loop, activating the enzyme for histone/protein acetylation. This data challenges the long-held belief that SCFAs mainly regulate chromatin by inhibiting HDACs, and instead reveals a previously unknown mechanism of HAT activation that can explain how an influx of low levels of SCFAs alters global chromatin states.

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Listeria monocytogenes Stimulates Mucus Exocytosis in Cultured Human Polarized Mucosecreting Intestinal Cells through Action of Listeriolysin O

Infection and Immunity ◽

10.1128/iai.66.8.3673-3681.1998 ◽

1998 ◽

Vol 66 (8) ◽

pp. 3673-3681 ◽

Cited By ~ 34

Author(s):

Marie-Hélène Coconnier ◽

Elyess Dlissi ◽

Myriam Robard ◽

Christian L. Laboisse ◽

Jean-Louis Gaillard ◽

...

Keyword(s):

Listeria Monocytogenes ◽

Direct Action ◽

Membrane Vesicle ◽

Regulatory System ◽

Cell Entry ◽

Intracellular Pathogen ◽

Listeriolysin O ◽

Stimulatory Action ◽

Isogenic Mutants ◽

Stimulation Of

ABSTRACT When the intracellular pathogen Listeria monocytogenesinfects cultured human mucosecreting polarized HT29-MTX cells apically, it induces the stimulation of mucus exocytosis without cell entry. Using a set of isogenic mutants and purified listeriolysin O (LLO), we identified the L. monocytogenes thiol-activated exotoxin LLO as the agonist of mucus secretion. We demonstrated that the LLO-induced mucus exocytosis did not result from the LLO membrane-damaging activity. We found that LLO-induced mucus exocytosis is an event requiring the binding of LLO to a brush border-associated receptor and membrane oligomerization of the exotoxin. By a pharmacological approach, we demonstrated that no regulatory system or intracellular transducing signal known to be involved in control of mucin exocytosis was activated by LLO. Based on the present data, the stimulatory action of LLO on mucin exocytosis could be accounted for either by an unknown signaling system which remains to be determined or by direct action of LLO with the membrane vesicle components involved in the intracellular vesicular transport of mucins.

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Lactiplantibacillus plantarum subsp. plantarum and Fructooligosaccharides Combination Inhibits the Growth, Adhesion, Invasion, and Virulence of Listeria monocytogenes

Foods ◽

10.3390/foods11020170 ◽

2022 ◽

Vol 11 (2) ◽

pp. 170

Author(s):

Qingli Dong ◽

Xinxin Lu ◽

Binru Gao ◽

Yangtai Liu ◽

Muhammad Zohaib Aslam ◽

...

Keyword(s):

Listeria Monocytogenes ◽

Incubation Temperature ◽

Foodborne Pathogen ◽

Untreated Group ◽

Listeriolysin O ◽

Regulatory Factor ◽

Gene Expressions ◽

Internalin B ◽

Serotype 4B ◽

Internalin A

Listeria monocytogenes is a foodborne pathogen responsible for many food outbreaks worldwide. This study aimed to investigate the single and combined effect of fructooligosaccharides (FOS) and Lactiplantibacillus plantarum subsp. plantarum CICC 6257 (L. plantarum) on the growth, adhesion, invasion, and virulence of gene expressions of Listeria monocytogenes 19112 serotype 4b (L. monocytogenes). Results showed that L. plantarum combined with 2% and 4% (w/v) FOS significantly (p < 0.05) inhibited the growth of L. monocytogenes (3–3.5 log10 CFU/mL reduction) at the incubation temperature of 10 °C and 25 °C. Under the same combination condition, the invasion rates of L. monocytogenes to Caco-2 and BeWo cells were reduced more than 90% compared to the result of the untreated group. After L. plantarum was combined with the 2% and 4% (w/v) FOS treatment, the gene expression of actin-based motility, sigma factor, internalin A, internalin B, positive regulatory factor A, and listeriolysin O significantly (p < 0.05) were reduced over 91%, 77%, 92%, 89%, 79%, and 79% compared to the result of the untreated group, respectively. The inhibition level of the L. plantarum and FOS combination against L. monocytogenes was higher than that of FOS or L. plantarum alone. Overall, these results indicated that the L. plantarum and FOS combination might be an effective formula against L. monocytogenes.

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Phosphocholine Antagonizes Listeriolysin O-Induced Host Cell Responses of Listeria monocytogenes

The Journal of Infectious Diseases ◽

10.1093/infdis/jiaa022 ◽

2020 ◽

Vol 222 (9) ◽

pp. 1505-1516 ◽

Cited By ~ 3

Author(s):

Luigi La Pietra ◽

Martina Hudel ◽

Helena Pillich ◽

Mobarak Abu Mraheil ◽

Besim Berisha ◽

...

Keyword(s):

Listeria Monocytogenes ◽

Potent Inhibitor ◽

Membrane Integrity ◽

Host Cells ◽

Calcium Flux ◽

Intracellular Pathogen ◽

Listeriolysin O ◽

Wild Type ◽

Cell Responses ◽

Isogenic Mutants

Abstract Background Bacterial toxins disrupt plasma membrane integrity with multitudinous effects on host cells. The secreted pore-forming toxin listeriolysin O (LLO) of the intracellular pathogen Listeria monocytogenes promotes egress of the bacteria from vacuolar compartments into the host cytosol often without overt destruction of the infected cell. Intracellular LLO activity is tightly controlled by host factors including compartmental pH, redox, proteolytic, and proteostatic factors, and inhibited by cholesterol. Methods Combining infection studies of L. monocytogenes wild type and isogenic mutants together with biochemical studies with purified phospholipases, we investigate the effect of their enzymatic activities on LLO. Results Here, we show that phosphocholine (ChoP), a reaction product of the phosphatidylcholine-specific phospholipase C (PC-PLC) of L. monocytogenes, is a potent inhibitor of intra- and extracellular LLO activities. Binding of ChoP to LLO is redox-independent and leads to the inhibition of LLO-dependent induction of calcium flux, mitochondrial damage, and apoptosis. ChoP also inhibits the hemolytic activities of the related cholesterol-dependent cytolysins (CDC), pneumolysin and streptolysin. Conclusions Our study uncovers a strategy used by L. monocytogenes to modulate cytotoxic LLO activity through the enzymatic activity of its PC-PLC. This mechanism appears to be widespread and also used by other CDC pore-forming toxin-producing bacteria.

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Short chain fatty acids modulate flagella expression in enterohemorrhagic Escherichia coli

10.32920/ryerson.14648442 ◽

2021 ◽

Author(s):

Jee In Kim

Keyword(s):

Escherichia Coli ◽

Short Chain Fatty Acids ◽

Enterohemorrhagic Escherichia Coli ◽

Short Chain ◽

Environmental Signals ◽

Component Systems ◽

Two Component Systems ◽

Sense And Respond ◽

And Function ◽

Fatty Acid Mixtures

During passage through the human gastrointestinal tract, enterohemorrhagic Escherichia coli (EHEC) encounters numerous stresses. EHEC utilizes various strategies to combat and survive these host assaults and possibly employs them as cues about the local microenvironment to enhance infection. This investigation looks at how exposure to changing concentrations of short chain fatty acid mixtures (SCFA) associated with passage through the human small (SI) and large intestines (LI) affects EHEC flagella expression and motility. In addition, the study also examines several two component systems for their involvement with SCFA-induced flagella regulation. The results indicate that SCFA mixture typical of SI may cue increased EHEC flagellar expression and function while SCFA mixture typical of LI, the site of EHEC colonization, may promote diminished flagella expression and function. Overall, this study contributes to our knowledge on how EHEC sense and respond to host environmental signals in a way that may promote to infection.

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Short chain fatty acids modulate flagella expression in enterohemorrhagic Escherichia coli

10.32920/ryerson.14648442.v1 ◽

2021 ◽

Author(s):

Jee In Kim

Keyword(s):

Escherichia Coli ◽

Short Chain Fatty Acids ◽

Enterohemorrhagic Escherichia Coli ◽

Short Chain ◽

Environmental Signals ◽

Component Systems ◽

Two Component Systems ◽

Sense And Respond ◽

And Function ◽

Fatty Acid Mixtures

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The Opposing Role of Propionate in Modulating Listeria monocytogenes Intracellular Infections

Frontiers in Microbiology ◽

10.3389/fmicb.2021.721801 ◽

2021 ◽

Vol 12 ◽

Author(s):

Laura Hobbs ◽

Leah Allen ◽

Megan Bias ◽

Stephanie Johnson ◽

Hannah DeRespiris ◽

...

Keyword(s):

Listeria Monocytogenes ◽

Host Cells ◽

Host Responses ◽

Listeriolysin O ◽

Food Ingredient ◽

Host Interactions ◽

Raw264.7 Macrophages ◽

Intracellular Infections ◽

The Impact

Listeria monocytogenes is a Gram-positive, intracellular pathogen responsible for the highly fatal foodborne illness listeriosis. Establishing intracellular infections requires the coordinated expressions of a variety of virulence factors, such as the pore-forming toxin listeriolysin O (LLO), in response to various intra- and extracellular signals. For example, we previously reported that L. monocytogenes differentially modulated LLO production in response to exogenous propionate, a short chain fatty acid either used in salt form as a human food ingredient or produced endogenously by gut microbial fermentation. Therefore, propionate is likely a continuously present signal throughout the L. monocytogenes transmission and infection process. However, little is known about the role of propionate in modulating L. monocytogenes-host interactions. Here we investigated the impact of propionate treatment on L. monocytogenes intracellular infections using cell culture infection models. Propionate treatment was performed separately on L. monocytogenes or host cells before or during infections to better distinguish pathogen-versus-host responses to propionate. Intracellular CFU in RAW264.7 macrophages and plaque diameters in L-fibroblasts were measured as proxy for intracellular infection outcomes. Nitrite levels and cellular morphology were also measured to assess host responses to propionate. We found that propionate pretreatment of anaerobic, but not aerobic, L. monocytogenes significantly enhanced subsequent intracellular infections in both cell types and nitrite production by infected macrophages. Propionate treatment of uninfected macrophages significantly altered cell morphology, seen by longer cells and greater migration, and reduced nitrite concentration in activated macrophages. Treatment of macrophages with propionate prior to or during infections significantly inhibited intracellular growth of L. monocytogenes, including those pre-treated with propionate. These results showcased an opposing effect of propionate on L. monocytogenes intracellular infections and strongly support propionate as an important signaling molecule for both the pathogen and the host cell that can potentially alter the outcome of L. monocytogenes-host interactions.

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