Project description:Biofilms are heterogeneous bacterial communities featured by high persister prevalence, responsible for antibiotic tolerance. However, the mechanisms underlying persister formation within biofilms remained ambiguous. Here, by developing and utilizing a ribosomal RNA depleted bacterial single-cell RNA-seq method, RiboD-mSPLiT, we resolved biofilm heterogeneity and discovered pdeI as a marker gene for persister subgroup within biofilms. Remarkably, our findings elucidated that PdeI upregulates cellular levels of c-di-GMP, which acts as an antitoxin to modulate the toxicity of toxin protein HipH. HipH localizes on nucleoid and functions as a potent DNase, inducing cells into a viable but non-culturable state. Conversely, c-di-GMP interacts with HipH, reducing its genotoxic effects and enabling cells to enter a persister state, resulting in drug tolerance. Importantly, by targeting this toxin-antitoxin system, we repressed drug tolerance in Uropathogenic Escherichia coli infections, offering promising therapeutic strategies against chronic and relapsing infections.
Project description:Biofilms are heterogeneous bacterial communities featured by high persister prevalence, responsible for antibiotic tolerance. However, the mechanisms underlying persister formation within biofilms remained ambiguous. Here, by developing and utilizing a ribosomal RNA depleted bacterial single-cell RNA-seq method, RiboD-mSPLiT, we resolved biofilm heterogeneity and discovered pdeI as a marker gene for persister subgroup within biofilms. Remarkably, our findings elucidated that PdeI upregulates cellular levels of c-di-GMP, which acts as an antitoxin to modulate the toxicity of toxin protein HipH. HipH localizes on nucleoid and functions as a potent DNase, inducing cells into a viable but non-culturable state. Conversely, c-di-GMP interacts with HipH, reducing its genotoxic effects and enabling cells to enter a persister state, resulting in drug tolerance. Importantly, by targeting this toxin-antitoxin system, we repressed drug tolerance in Uropathogenic Escherichia coli infections, offering promising therapeutic strategies against chronic and relapsing infections.
Project description:Biofilms are heterogeneous bacterial communities featured by high persister prevalence, responsible for antibiotic tolerance. However, the mechanisms underlying persister formation within biofilms remained ambiguous. Here, by developing and utilizing a ribosomal RNA depleted bacterial single-cell RNA-seq method, RiboD-mSPLiT, we resolved biofilm heterogeneity and discovered pdeI as a marker gene for persister subgroup within biofilms. Remarkably, our findings elucidated that PdeI upregulates cellular levels of c-di-GMP, which acts as an antitoxin to modulate the toxicity of toxin protein HipH. HipH localizes on nucleoid and functions as a potent DNase, inducing cells into a viable but non-culturable state. Conversely, c-di-GMP interacts with HipH, reducing its genotoxic effects and enabling cells to enter a persister state, resulting in drug tolerance. Importantly, by targeting this toxin-antitoxin system, we repressed drug tolerance in Uropathogenic Escherichia coli infections, offering promising therapeutic strategies against chronic and relapsing infections.
Project description:Nitric oxide (NO) signaling in vertebrates is well characterized and involves the heme-nitric oxide/oxygen-binding (H-NOX) domain of soluble guanylate cyclase as a selective NO sensor. In contrast, little is known about the biological role or signaling output of bacterial H-NOX proteins. Here, we describe a molecular pathway for H-NOX signaling in Shewanella oneidensis. NO stimulates biofilm formation by controlling the levels of the bacterial secondary messenger cyclic diguanosine monophosphate (c-di-GMP). Phosphotransfer profiling was used to map the connectivity of a multicomponent signaling network that involves integration from two histidine kinases and branching to three response regulators. A feed-forward loop between response regulators with phosphodiesterase domains and phosphorylation-mediated activation intricately regulated c-di-GMP levels. Phenotypic characterization established a link between NO signaling and biofilm formation. Cellular adhesion may provide a protection mechanism for bacteria against reactive and damaging NO. These results are broadly applicable to H-NOX-mediated NO signaling in bacteria.
Project description:Bis-(3',5')-cyclic-dimeric-guanosine monophosphate (c-di-GMP) has been shown to be a global regulatory molecule that modulates the reciprocal responses of bacteria to activate either virulence pathways or biofilm formation. The mechanism of c-di-GMP signal transduction, including recognition of c-di-GMP and subsequent phenotypic regulation, remain largely uncharacterized. The key components of these regulatory pathways are the various adaptor proteins (c-di-GMP receptors). There is compelling evidence suggesting that, in addition to PilZ domains, there are other unidentified c-di-GMP receptors. Here we show that the PelD protein of Pseudomonas aeruginosa is a novel c-di-GMP receptor that mediates c-di-GMP regulation of PEL polysaccharide biosynthesis. Analysis of PelD orthologues identified a number of conserved residues that are required for c-di-GMP binding as well as synthesis of the PEL polysaccharide. Secondary structure similarities of PelD to the inhibitory site of diguanylate cyclase suggest that a common fold can act as a platform to bind c-di-GMP. The combination of a c-di-GMP binding site with a variety of output signalling motifs within one protein domain provides an explanation for the specificity for different cellular responses to this regulatory dinucleotide.
Project description:Francisella tularensis is a gram-negative bacterium that is highly virulent in humans, causing the disease tularemia. F. novicida is closely related to F. tularensis and exhibits high virulence in mice, but it is avirulent in healthy humans. An F. novicida-specific gene cluster (FTN0451 to FTN0456) encodes two proteins with diguanylate cyclase (DGC) and phosphodiesterase (PDE) domains that modulate the synthesis and degradation of cyclic di-GMP (cdGMP). No DGC- or PDE-encoding protein genes are present in the F. tularensis genome. F. novicida strains lacking either the two DGC/PDE genes (cdgA and cdgB) or the entire gene cluster (strain KKF457) are defective for biofilm formation. In addition, expression of CdgB or a heterologous DGC in strain KKF457 stimulated F. novicida biofilms, even in a strain lacking the biofilm regulator QseB. Genetic evidence suggests that CdgA is predominantly a PDE, while CdgB is predominantly a DGC. The F. novicida qseB strain showed reduced cdgA and cdgB transcript levels, demonstrating an F. novicida biofilm signaling cascade that controls cdGMP levels. Interestingly, KKF457 with elevated cdGMP levels exhibited a decrease in intramacrophage replication and virulence in mice, as well as increased growth yields and biofilm formation in vitro. Microarray analyses revealed that cdGMP stimulated the transcription of a chitinase (ChiB) known to contribute to biofilm formation. Our results indicate that elevated cdGMP in F. novicida stimulates biofilm formation and inhibits virulence. We suggest that differences in human virulence between F. novicida and F. tularensis may be due in part to the absence of cdGMP signaling in F. tularensis.