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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.

Conservons are operons that encode unusual regulatory systems found in bacteria of the phylum Actinomycetota. These regulatory systems are composed of four core proteins: a sensor histidine kinase-like protein (CvnA homolog), an MglB-type roadblock protein (CvnB homolog), a protein containing a domain of unknown function (CvnC homolog), and a small Ras-like GTPase (CvnD homolog). Based on their conserved small GTPase components and their phylogenetic distribution, we propose that the systems encoded by conservons should be known as ctinobacterial rotein ystems (AGPSs). The signal transduction path through AGPSs remains poorly understood, and some AGPSs have additional accessory proteins (CvnE and CvnF homologs) of unknown function. In this work, we show that AGPS accessory proteins are present when the cognate histidine kinase protein (CvnA homolog) lacks an extracytoplasmic sensory domain. It was previously shown that the Cvn8 AGPS of controls the expression of multiple pathways for specialized metabolism. The Cvn8 AGPS also contains an accessory protein, CvnF8. Through protein modeling, we found that CvnF8 may share an interaction interface with the histidine kinase CvnA8, prompting the hypothesis that CvnF8 may act as a modulator of CvnA8 activity. Consistent with this hypothesis, we found that when co-expressed in a heterologous host, CvnA8 and CvnF8 were purified as a stable complex. In a purified system, CvnF8 strongly stimulated the ATPase activity and autophosphorylation of CvnA8. Taken together, these findings indicate that CvnF family accessory proteins likely serve as sensors and/or modulators of histidine kinases of AGPSs found broadly in Actinomycetota. Many lineages of bacteria in the phylum Actinomycetota contain conserved operons (conservons) that encode an unusual type of regulatory system whose function is poorly understood. These lineages include pathogens such as and members of the genus that produce valuable natural products. These regulatory systems are composed of four proteins, including a sensor histidine kinase and a small Ras-like GTPase. We propose that these regulatory systems be known as actinobacterial G protein systems (AGPSs). We show that some AGPSs include accessory proteins that are only found with partner histidine kinases that lack sensory domains. We demonstrate that one such accessory protein can control the activity of its cognate histidine kinase. Our findings indicate that these CvnF-family accessory proteins likely serve as sensory inputs for AGPSs found broadly in Actinomycetota. This work sheds light on the initial steps of signal transduction within these unusual regulatory systems.

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.

Pseudomonas aeruginosa is a metabolically versatile environmental pathogen whose virulence relies on coordinated expression of catabolic genes, particularly the histidine utilization ( hut ) operon. Disruption of the hut operon reduces virulence, but the underlying mechanism remains rudimentary. Here, we genetically characterized the histidine-responsive transcriptional factor HutC in P. aeruginosa PAO1, alongside HutC in the non-pathogenic strain Pseudomonas fluorescens SBW25. Two important features emerged. First, HutC recognizes two distinct DNA-binding motifs with little sequence similarity; notably, a noncanonical-binding site was identified in the hutF promoter of SBW25 but was absent in PAO1. Second, HutC exhibits low-affinity binding to genes beyond histidine catabolism and contributes to the expression of multiple virulence traits. These findings identify HutC as a local regulator linking histidine catabolism with virulence and as a unique prokaryotic model for studying how noncanonical transcriptional factor-DNA interactions achieve binding specificity, a phenomenon so far investigated only in eukaryotes.

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.

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.

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.