Free Fatty Acids Interfere with the DNA Binding Activity of the Virulence Regulator PrfA of Listeria monocytogenes

Santos, Patricia Isabel Teixeira dos; Thomasen, Rikke Scheel; Green, Mathias S.; Færgeman, Nils J.; Kallipolitis, Birgitte H.

doi:10.1128/jb.00156-20

Cited by 13 publications

(32 citation statements)

References 52 publications

(93 reference statements)

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“…monocytogenes has also been found inside large, single-membrane vacuoles in splenic macrophages of immune-competent mice [ 34 ], suggesting that at least a subset of bacteria might assume an intravacuolar state, be it temporary or prolonged, within an immune-competent host. This scenario seems conceivable given the heterogeneity of intracellular bacterial fate upon infection [ 22 ] and recent insights that PrfA activity is regulated by peptides derived from nutritional sources as well as free fatty acids [ 14 , 35 ]. Nevertheless, whether Listeria -residence vacuoles in vivo resemble any of the vacuolar compartments defined in in vitro studies remains to be determined.…”

Section: Discussionmentioning

confidence: 99%

Inhibition of the master regulator of Listeria monocytogenes virulence enables bacterial clearance from spacious replication vacuoles in infected macrophages

et al. 2022

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A hallmark of Listeria (L.) monocytogenes pathogenesis is bacterial escape from maturing entry vacuoles, which is required for rapid bacterial replication in the host cell cytoplasm and cell-to-cell spread. The bacterial transcriptional activator PrfA controls expression of key virulence factors that enable exploitation of this intracellular niche. The transcriptional activity of PrfA within infected host cells is controlled by allosteric coactivation. Inhibitory occupation of the coactivator site has been shown to impair PrfA functions, but consequences of PrfA inhibition for L. monocytogenes infection and pathogenesis are unknown. Here we report the crystal structure of PrfA with a small molecule inhibitor occupying the coactivator site at 2.0 Å resolution. Using molecular imaging and infection studies in macrophages, we demonstrate that PrfA inhibition prevents the vacuolar escape of L. monocytogenes and enables extensive bacterial replication inside spacious vacuoles. In contrast to previously described spacious Listeria-containing vacuoles, which have been implicated in supporting chronic infection, PrfA inhibition facilitated progressive clearance of intracellular L. monocytogenes from spacious vacuoles through lysosomal degradation. Thus, inhibitory occupation of the PrfA coactivator site facilitates formation of a transient intravacuolar L. monocytogenes replication niche that licenses macrophages to effectively eliminate intracellular bacteria. Our findings encourage further exploration of PrfA as a potential target for antimicrobials and highlight that intra-vacuolar residence of L. monocytogenes in macrophages is not inevitably tied to bacterial persistence.

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Section: Discussionmentioning

confidence: 99%

Inhibition of the master regulator of Listeria monocytogenes virulence enables bacterial clearance from spacious replication vacuoles in infected macrophages

et al. 2022

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“…In contrast, antimicrobial medium- and long-chain free fatty acids (FFAs) prevent the expression of PrfA-dependent genes, a repression that can overcome the effect of a mid-level constitutively active EGD G155S- prfA ∗ mutant ( Lillebæk et al, 2017 ). The repressor mechanism occurs by free fatty acids interfering with the DNA binding activity of PrfA ( Dos Santos et al, 2020 ). Similarly, our studies showed that the chitin polymer repressed PrfA-dependent expression in both a WT strain and a G155S- prfA ∗ mutant and suggest that a post-translational modification of PrfA ∗ may inhibit the activity of the protein in CDM.…”

Section: Discussionmentioning

confidence: 99%

Chitin Attenuates Expression of Listeria monocytogenes Virulence Genes in vitro

et al. 2020

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External signals are crucial for bacteria to sense their immediate environment and fine-tune gene expression accordingly. The foodborne pathogen Listeria monocytogenes senses a range of environmental cues in order to activate or deactivate the virulence-inducing transcriptional factor PrfA during transition between infectious and saprophytic lifecycles. Chitin is an abundant biopolymer formed from linked β-(1–4)-N-acetyl-D-glucosamine residues associated with fungi, the exoskeleton of insects and often incorporated into foods as a thickener or stabilizer. L. monocytogenes evolved to hydrolyse chitin, presumably, to facilitate nutrient acquisition from competitive environments such as soil where the polymer is abundant. Since mammals do not produce chitin, we reasoned that the polymer could serve as an environmental signal contributing to repression of L. monocytogenes PrfA-dependent expression. This study shows a significant downregulation of the core PrfA-regulon during virulence-inducing conditions in vitro in the presence of chitin. Our data suggest this phenomenon occurs through a mechanism that differs from PTS-transport of oligosaccharides generated from either degradation or chitinase-mediated hydrolysis of the polymer. Importantly, an indication that chitin can repress virulence expression of a constitutively active PrfA∗ mutant is shown, possibly mediated via a post-translational modification inhibiting PrfA∗ activity. To our knowledge, this is the first time that chitin is reported as a molecule with anti-virulence properties against a pathogenic bacterium. Thus, our findings identify chitin as a signal which may downregulate the virulence potential of the pathogen and may provide an alternative approach toward reducing disease risk.

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“…In Listeria monocytogenes, this includes regulatory targets of the master regulatory protein PrfA (Sternkopf Lillebaek et al, 2017) since free fatty acids alter the expression of PrfA-dependent genes (Sternkopf Lillebaek et al, 2017). Recently, it was shown that free fatty acids can prevent activated PrfA from binding DNA (Dos Santos et al, 2020). This data suggest that fatty acids could prevent other regulatory proteins such as SaeR from binding DNA.…”

Section: Our Data Indicate That Fatty Acids Not Commonly Found Inmentioning

confidence: 99%

Fatty acids can inhibit Staphylococcus aureus SaeS activity at the membrane independent of alterations in respiration

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et al. 2021

Molecular Microbiology

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According to the Centers of Disease Control and Prevention (CDC), approximately 2.8 million people in the U.S. are infected by antibiotic-resistant bacteria each year. It is estimated that antibioticresistant Staphylococcus aureus accounted for over 300,000 hospitalizations and over 10,000 deaths in 2017, indicating that S. aureus is a key contributor to the burden of antibiotic-resistant infections (CDC). S. aureus is a Gram-positive bacterium that asymptomatically colonizes 20%-30% of the population, predominately in the anterior nares and the skin (Lowy, 1998). Despite being asymptomatic, S. aureus can opportunistically establish infections in nearly every anatomical site but most commonly causes infections in the skin (Pallin et al., 2008;Suaya et al., 2014). This bacterium is responsible for most of the skin and soft-tissue infections observed in the clinic (Moran et al., 2006) and was estimated to cost the U.S. healthcare system $1.7 billion in 2017 (CDC). With the large burden that S. aureus places on the healthcare system, an emphasis on understanding what makes S. aureus such a successful pathogen and designing novel targeted therapeutics is needed. S. aureus must be able to adapt to individual niches on and withinthe host to ensure well-timed regulation of its virulence arsenal to be a successful pathogen. Environmental cues include changes in osmolarity, temperature, presence, or absence of oxygen, pH, and host-associated factors. Some of these signals are sensed by two-component systems (TCS) which allow bacteria to respond to stimuli and adjust target gene expression accordingly (Tiwari et al., 2017;Wang, 2012). S. aureus possesses 16 TCS that respond to

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Free Fatty Acids Interfere with the DNA Binding Activity of the Virulence Regulator PrfA of Listeria monocytogenes

Cited by 13 publications

References 52 publications

Inhibition of the master regulator of Listeria monocytogenes virulence enables bacterial clearance from spacious replication vacuoles in infected macrophages

Inhibition of the master regulator of Listeria monocytogenes virulence enables bacterial clearance from spacious replication vacuoles in infected macrophages

Chitin Attenuates Expression of Listeria monocytogenes Virulence Genes in vitro

Fatty acids can inhibit Staphylococcus aureus SaeS activity at the membrane independent of alterations in respiration

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