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The classical TCS system in bacterial signal transduction is composed of two proteins—a histidine kinase and its cognate response regulator. More and more studies have revealed the presence of accessory proteins that can modulate the histidine kinase activity and affect signal transduction, but their mechanisms remain largely elusive. This study unveils a previously unrecognized mechanism by which bacterial accessory lipoproteins mediate TCS activation. We provide compelling evidence that QseG directly interacts with QseE through an evolutionarily conserved structural interface, readily and sufficiently activating QseE’s autokinase activity and downstream signaling. Given the essential role of QseEF in bacterial virulence and stress adaptation, our findings pave the way for the development of antimicrobial strategies targeting this conserved lipoprotein-mediated activation mechanism.

There is a groundswell of interest in using genetically engineered sensor bacteria to study gut microbiota pathways, and diagnose or treat associated diseases. Here, we computationally identify the first biological thiosulfate sensor and an improved tetrathionate sensor, both two‐component systems from marine Shewanella species, and validate them in laboratory Escherichia coli . Then, we port these sensors into a gut‐adapted probiotic E. coli strain, and develop a method based upon oral gavage and flow cytometry of colon and fecal samples to demonstrate that colon inflammation (colitis) activates the thiosulfate sensor in mice harboring native gut microbiota. Our thiosulfate sensor may have applications in bacterial diagnostics or therapeutics. Finally, our approach can be replicated for a wide range of bacterial sensors and should thus enable a new class of minimally invasive studies of gut microbiota pathways. Synopsis A sensor bacterium that uses a novel two‐component signaling system is engineered to detect thiosulfate and colon inflammation. This work suggests thiosulfate as a novel biomarker of colon inflammation and demonstrates the potential of engineered bacteria in disease diagnostics. Novel two‐component system sensors of thiosulfate and tetrathionate from marine Shewanella species are identified computationally. Both sensors are characterized in laboratory Escherichia coli and then ported to the gut‐adapted probiotic strain Nissle 1917. A flow cytometry protocol is developed for identifying the engineered bacteria in the colon contents or feces of mice with intact microbiota. The thiosulfate sensor has elevated output in inflamed mice, suggesting thiosulfate as a novel biomarker of inflammation. Graphical Abstract A sensor bacterium that uses a novel two‐component signaling system is engineered to detect thiosulfate and colon inflammation. This work suggests thiosulfate as a novel biomarker of colon inflammation and demonstrates the potential of engineered bacteria in disease diagnostics.

Vortex shedding from a moving obstacle potential in a two-component Bose-Einstein condensate is investigated numerically. For a miscible two-component condensate composed of 23Na and 87Rb atoms, in the wake of obstacle, the Kármán vortex street is discovered in one component, while the Kármán-like vortex street named 'half-quantum vortex street' is formed in another component. The other patterns of vortex shedding, such as the vortex dipoles, V-shaped vortex pairs and corresponding 'half-quantum vortex shedding', can also be found. The drag force acting on obstacle potential is calculated and discussed. The parameter region for various vortex patterns and critical velocity for vortex emission are presented. In addition, a 85Rb-87Rb mixture is also considered, where the Kármán vortex street and other typical patterns exist in both components. Finally, we provide an experimental protocol for the above realization and observation.

We have observed and characterized the nonequilibrium spatial dynamics of a two-component 87Rb Bose-Einstein condensate (BEC) that is controllable switched back and forth between the miscible and immiscible phases of the phase separation transition by changing the internal states of the 87Rb atoms. The subsequent evolution exhibits large scale oscillations of the spatial structure that involve component mixing and separation. We show that the larger total energy of the miscible system results in a higher oscillation frequency. This investigation introduces a new technique to control the miscibility and the spatial degrees of freedom in atomic BECs.

In this paper, we have developed two local discontinuous Galerkin (LDG) methods for the two-component μ -Camassa-Holm equations: a conservative scheme and a dissipative scheme. Exploiting the bi-Hamiltonian structure of the two-component μ -Camassa-Holm system, we introduce two significant Hamiltonian invariants and demonstrate that both schemes preserve discrete versions of these invariants. Additionally, we provide and prove a priori error estimates for both LDG schemes. Numerical experiments are conducted to validate the accuracy and effectiveness of the proposed methods.

Plant pathogenic bacteria of the genus Xanthomonas cause a variety of diseases in economically important monocotyledonous and dicotyledonous crop plants worldwide. Successful infection and bacterial multiplication in the host tissue often depend on the virulence factors secreted including adhesins, polysaccharides, LPS and degradative enzymes. One of the key pathogenicity factors is the type III secretion system, which injects effector proteins into the host cell cytosol to manipulate plant cellular processes such as basal defense to the benefit of the pathogen. The coordinated expression of bacterial virulence factors is orchestrated by quorum-sensing pathways, multiple two-component systems and transcriptional regulators such as Clp, Zur, FhrR, HrpX and HpaR. Furthermore, virulence gene expression is post-transcriptionally controlled by the RNA-binding protein RsmA. In this review, we summarize the current knowledge on the infection strategies and regulatory networks controlling secreted virulence factors from Xanthomonas species.

Polymyxins (polymyxin B and colistin) are last-line antibiotics against multidrug-resistant Gram-negative pathogens. Polymyxin resistance is increasing worldwide, with resistance most commonly regulated by two-component systems such as PmrAB and PhoPQ. This review discusses the regulatory mechanisms of PhoPQ and PmrAB in mediating polymyxin resistance, from receiving an external stimulus through to activation of genes responsible for lipid A modifications. By analyzing the reported nonsynonymous substitutions in each two-component system, we identified the domains that are critical for polymyxin resistance. Notably, for PmrB 71% of resistance-conferring nonsynonymous mutations occurred in the HAMP (present in histidine kinases, adenylate cyclases, methyl accepting proteins and phosphatase) linker and DHp (dimerization and histidine phosphotransfer) domains. These results enhance our understanding of the regulatory mechanisms underpinning polymyxin resistance and may assist with the development of new strategies to minimize resistance emergence.

The rational creation of two-component conjugated polymer systems with high levels of phase purity in each component is challenging but crucial for realizing printed soft-matter electronics. Here, we report a mixed-flow microfluidic printing (MFMP) approach for two-component π-polymer systems that significantly elevates phase purity in bulk-heterojunction solar cells and thinfilm transistors. MFMP integrates laminar and extensional flows using a specially microstructured shear blade, designed with fluid flow simulation tools to tune the flow patterns and induce shear, stretch, and pushout effects. This optimizes polymer conformation and semi-conducting blend order as assessed by atomic force microscopy (AFM), transmission electron microscopy (TEM), grazing incidence wide-angle X-ray scattering (GIWAXS), resonant soft X-ray scattering (R-SoXS), photovoltaic response, and field effect mobility. For printed all-polymer (poly[(5,6-difluoro-2-octyl-2H-benzotriazole-4,7-diyl)-2,5-thiophenediyl[ 4,8-bis[5-(2-hexyldecyl)-2-thienyl]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl]-2,5-thiophenediyl]) [J51]:(poly{[N,N′-bis(2-octyldodecyl) naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5′-(2,2′-bithiophene)}) [N2200]) solar cells, this approach enhances short-circuit currents and fill factors,with power conversion efficiency increasing from 5.20% for conventional blade coating to 7.80% for MFMP. Moreover, the performance of mixed polymer ambipolar [poly(3-hexylthiophene-2,5-diyl) (P3HT):N2200] and semiconducting:insulating polymer unipolar (N2200:polystyrene) transistors is similarly enhanced, underscoring versatility for two-component π-polymer systems. Mixed-flow designs offer modalities for achieving high-performance organic optoelectronics via innovative printing methodologies.

Bacteria constantly sense and respond to their surroundings through two-component systems. In Gram-negative bacteria, phosphate sensing is mediated by the PhoB/PhoR two-component system with additional components, the PstSCAB phosphate transporter and the PhoU protein. Bacteria utilize two-component regulatory systems to sense and respond to their surroundings. Unlike other two-component systems that directly sense through a sensory domain in the histidine kinase (HK), the PhoB/PhoR two-component system requires additional proteins, including the PstSCAB phosphate transporter and the PhoU protein, to sense phosphate levels. Although PhoU is involved in phosphate signaling by connecting the PstSCAB transporter and PhoR histidine kinase, the mechanism by which PhoU controls expression of pho regulon genes has not yet been clearly understood. Here, we identified PhoU residues required for interacting with PhoR histidine kinase from the intracellular pathogen Salmonella enterica serovar Typhimurium. The PhoU Ala147 residue interacts with the PhoR PAS domain and is involved in repressing pho expression in high phosphate. Unexpectedly, the PhoU Arg184 residue interacts with the PhoR histidine kinase domain and is required for activating pho expression in low Mg 2+ by increasing PhoR autophosphorylation, revealing its new function. The substitution of the Arg184 to Gly codon decreased Salmonella virulence both in macrophages and in mice, suggesting that PhoU’s role in promoting PhoR autophosphorylation is required during Salmonella infection. IMPORTANCE Bacteria constantly sense and respond to their surroundings through two-component systems. In Gram-negative bacteria, phosphate sensing is mediated by the PhoB/PhoR two-component system with additional components, the PstSCAB phosphate transporter and the PhoU protein. PhoU, a regulatory protein that connects the PstSCAB phosphate transporter to the PhoB/PhoR two-component system, is believed to function as a negative regulator in phosphate signaling because the phoU deletion mutant loses the ability to repress pho expression in high phosphate. Using single amino acid substitutions in the intracellular pathogen Salmonella enterica serovar Typhimurium, PhoU turns out to control PhoR histidine kinase differently, depending on the conditions. The PhoU-PhoR PAS domain interaction is involved in repressing pho expression in high phosphate, whereas the PhoU-PhoR HK domain interaction is involved in activating autophosphorylation of PhoR histidine kinase in low Mg 2+ and thus promotes Salmonella virulence. Therefore, PhoU appears to modulate phosphate signaling exquisitely according to external conditions.

Lactiplantibacillus plantarum has a strong carbohydrate utilization ability. This characteristic plays an important role in its gastrointestinal tract colonization and probiotic effects. L. plantarum LP-F1 presents a high carbohydrate utilization capacity. The genome analysis of 165 L. plantarum strains indicated the species has a plenty of carbohydrate metabolism genes, presenting a strain specificity. Furthermore, two-component systems (TCSs) analysis revealed that the species has more TCSs than other lactic acid bacteria, and the distribution of TCS also shows the strain specificity. In order to clarify the sugar metabolism mechanism under different carbohydrate fermentation conditions, the expressions of 27 carbohydrate metabolism genes, catabolite control protein A (CcpA) gene ccpA, and TCSs genes were analyzed by quantitative real-time PCR technology. The correlation analysis between the expressions of regulatory genes and sugar metabolism genes showed that some regulatory genes were correlated with most of the sugar metabolism genes, suggesting that some TCSs might be involved in the regulation of sugar metabolism.