Two-component System Research Articles

Structure and distribution of sensor histidine kinases in the fungal kingdom.

Two-component systems (TCSs) are diverse cell signaling pathways that play a significant role in coping with a wide range of environmental cues in both prokaryotic and eukaryotic organisms. These transduction circuitries are primarily governed by histidine kinases (HKs), which act as sensing proteins of a broad variety of stressors. To date, nineteen HK groups have been previously described in the fungal kingdom. However, the structure and distribution of these prominent sensing proteins were hitherto investigated in a limited number of fungal species. In this study, we took advantage of recent genomic resources in fungi to refine the fungal HK classification by deciphering the structural diversity and phylogenetic distribution of HKs across a large number of fungal clades. To this end, we browsed the genome of 91 species representative of different fungal clades, which yielded 726 predicted HK sequences. A domain organization analysis, coupled with a robust phylogenomic approach, led to an improved categorization of fungal HKs. While most of the compiled sequences were categorized into previously described fungal HK groups, some new groups were also defined. Overall, this study provides an improved overview of the structure, distribution, and evolution of HKs in the fungal kingdom.

Persistence properties for a two-component b-family system with higher-order nonlinearity in weighted Lp spaces

In this paper, we focus on a two-component b-family system with higher-order nonlinearity, which contains some integrable Camassa–Holm type models. By virtue of moderate weight functions, we demonstrate the persistence properties for solutions to this system in weighted Lp spaces. Our persistence results cover and improve the related results of some Camassa–Holm type models.

OpgH is an essential regulator of Caulobacter morphology.

Bacterial growth and division rely on intricate regulation of morphogenetic complexes to remodel the cell envelope without compromising envelope integrity. Significant progress has been made in recent years towards understanding the regulation of cell wall metabolic enzymes. However, other cell envelope components play a role in morphogenesis as well. A primary factor required to protect envelope integrity in low osmolarity environments is OpgH, the synthase of osmoregulated periplasmic glucans (OPGs). Here, we demonstrate that OpgH is essential in the α-proteobacterium Caulobacter crescentus. Unexpectedly, depletion of OpgH or attempted complementation with a catalytically dead OpgH variant results in striking asymmetric bulging and cell lysis. These shape defects are accompanied by reduced cell wall synthesis and mislocalization of morphogenetic complexes. Interestingly, overactivation of the CenKR two-component system that has been implicated in cell envelope stress homeostasis in α-proteobacteria phenocopies the morphogenetic defects associated with OpgH depletion. Each of these perturbations leads to an increase in the levels of the elongasome protein, MreB, and decreases in the levels of divisome proteins FtsZ and MipZ as well as OpgH, itself. Constitutive production of OpgH during CenKR overactivation prevents cell bulging, but cells still exhibit morphogenetic defects. We propose that OPG depletion activates CenKR, leading to changes in the expression of cell envelope-related genes, but that OPGs also exert CenKR-independent effects on morphogenesis. Our data establish a surprising function for an OpgH homolog in morphogenesis and reveal an essential role of OpgH in maintaining cell morphology in Caulobacter.IMPORTANCEBacteria must synthesize and fortify the cell envelope in a tightly regulated manner to orchestrate growth and adaptation. Osmoregulated periplasmic glucans (OPGs) are important, but poorly understood, constituents of Gram-negative cell envelopes that contribute to envelope integrity and protect against osmotic stress. Here, we determined that the OPG synthase OpgH plays a surprising, essential role in morphogenesis in Caulobacter crescentus. Loss of OpgH causes asymmetric cell bulging and lysis via misregulation of the localization and activity of morphogenetic complexes. Overactivation of the CenKR two-component system involved in envelope homeostasis phenocopies OpgH depletion, suggesting that depletion of OpgH activates CenKR. Because cell envelope integrity is critical for bacterial survival, understanding how OpgH activity contributes to morphogenesis and maintenance of envelope integrity could aid in the development of antibiotic therapies.

Development of oriented microbial consortium-based compound enzyme strengthens food waste hydrolysis and antibiotic resistance genes removal: Deciphering of performance, metabolic pathways and microbial communities

Enzymatic hydrolysis has been considered as an eco-friendly pretreatment method for enhancing bioconversion process of food waste (FW). However, existing commercial enzymes and microbial monomer-based compound enzymes (MME) have the issues of uneven distribution of enzymatic activity and low matching degree with the components of FW, leading to low efficiency with enzymatic hydrolysis and removal of antibiotic resistance genes (ARGs). This study used FW as the substrate, under the co-culture system, produced a microbial consortium-based compound enzymes (MCE) with oriented and well-matching degree for FW hydrolysis and ARGs removal, of which the performance, metabolic pathways and microbial communities were also investigated in depth. Results showed that the best performance for ARGs was achieved by the MCE prepared by mixing 1:5 of Aspergillus oryzae and Aspergillus niger after 12 days fermentation. The highest soluble chemical oxygen demand (SCOD) concentration and ARGs removal could respectively reach 83.90 ± 1.67 g/L and 45.95% after MCE pretreatment. The analysis of metabolic pathways revealed that 1:5 MCE pretreatment strengthened the catalytic activity of carbohydrate-active enzymes, increased the abundances of genes involved in cellulose and starch degradation, polysaccharide synthesis, ATP binding cassette (ABC) transporters and global regulation, while decreased the abundances of genes involved in mating pair formation system, two-component regulatory systems and quorum sensing, thereby enhanced FW hydrolysis and restrained ARGs dissemination. Microbial community analysis further indicated that the 1:5 MCE pretreatment promoted growth, metabolism and richness of functional microbes, while inhibited the host microbes of ARGs. It is expected that this study can provide useful insights into understanding the fate of ARGs in food waste during MCE pretreatment process.

Multidimensional Nonhomogeneous Quasi-Linear Systems and Their Hamiltonian Structure

In this paper, we investigate multidimensional first-order quasi-linear systems and find necessary conditions for them to admit Hamiltonian formulation. The insufficiency of the conditions is related to the Poisson cohomology of the admissible Hamiltonian operators. We present in detail the examples of two-dimensional, two-components systems of hydrodynamic type and of a real reduction of the 3-waves system.

Microbial mechanisms for higher hydrogen production in anaerobic digestion at constant temperature versus gradient heating

BackgroundClean energy hydrogen (H2) produced from abundant lignocellulose is an alternative to fossil energy. As an essential influencing factor, there is a lack of comparison between constant temperatures (35, 55 and 65 °C) and gradient heating temperature (35 to 65 °C) on the H2 production regulation potential from lignocellulose-rich straw via high-solid anaerobic digestion (HS-AD). More importantly, the microbial mechanism of temperature regulating H2 accumulation needs to be investigated.ResultsConstant 65 °C led to the lowest lignin residue (1.93%) and the maximum release of cellulose and hemicellulose, and the highest H2 production (26.01 mL/g VS). H2 production at 35 and 55 °C was only 14.56 and 24.13 mL/g VS, respectively. In order to further explore the potential of ultra-high temperature (65 °C), HS-AD was performed by gradient heating conditions (35 to 65 °C). However, compared to constant 65 °C, gradient heating conditions led to higher lignin residue (2.49%) and lower H2 production (13.53 mL/g VS) than gradient heating conditions (47.98%). In addition, metagenomic analysis showed the cellulose/hemicellulose hydrolyzing bacteria and genes (mainly Thermoclostridium, and xynA, xynB, abfA, bglB and xynD), H2-producing bacteria and related genes (mainly Thermoclostridium, and nifD, nifH and nifK), and microbial movement and metabolic functions were enriched at 65 °C. However, the enrichment of two-component systems under gradient heating conditions resulted in a lack of highly-enriched ultra-high-temperature cellulose/hemicellulose hydrolyzing genera and related genes but rather enriched H2 consumption genera and genes (mainly Acetivibrio, and hyaB and hyaA) resulting in a weaker H2 production.ConclusionsThe lignin degradation process does not directly determine H2 accumulation, which was actually regulated by bacteria/genes contributing to H2 production/consumption. In addition, it is temperature that enhances the hydrolysis process of lignin rather than lignin-degrading enzymes, bacteria and genes by promoting microbial material transfer and metabolism. In terms of temperature, one of the key parameters of HS-AD for H2 production, we developed an important regulatory strategy, enriched the theoretical basis of temperature regulation for H2 production to further expanded the research horizon in this field.ABqfqNejHM5MQBNj5XnjcNVideo

PhoP/PhoQ Two-Component System Contributes to Intestinal Inflammation Induced by Cronobacter sakazakii in Neonatal Mice.

Cronobacter sakazakii (C. sakazakii) is a foodborne pathogen capable of causing severe infections in newborns. The PhoP/PhoQ two-component system exerts a significant influence on bacterial virulence. This study aimed to investigate the impact of the PhoP/PhoQ system on intestinal inflammation in neonatal mice induced by C. sakazakii. Neonatal mice were infected orally by C. sakazakii BAA-894 (WT), a phoPQ-gene-deletion strain (ΔphoPQ), and a complementation strain (ΔphoPQC), and the intestinal inflammation in the mice was monitored. Deletion of the phoPQ gene reduced the viable count of C. sakazakii in the ileum and alleviated intestinal tissue damage. Moreover, caspase-3 activity in the ileum of the WT- and ΔphoPQC-infected mice was significantly elevated compared to that of the ΔphoPQ and control groups. ELISA results showed elevated levels of TNF-α and IL-6 in the ileum of the mice infected with WT and ΔphoPQC. In addition, deletion of the phoPQ gene in C. sakazakii resulted in a down-regulation of inflammatory genes (IL-1β, TNF-α, IL-6, NF-κB p65, TLR4) within the ileum and decreased inflammation by modulating the TLR4/NF-κB pathway. It is suggested that targeting the PhoP/PhoQ two-component system could be a potential strategy for mitigating C. sakazakii-induced neonatal infections.

Power-law correlation in the homogeneous disordered state of anisotropically self-propelled systems

Self-propelled particles display unique collective phenomena, due to the intrinsic coupling of density and polarity. For instance, the giant number fluctuation appears in the orientationally ordered state, and the motility-induced phase separation appears in systems with repulsion. Effects of strong noise typically lead to a homogeneous disordered state, in which the coupling of density and polarity can still play a significant role. Here we study universal properties of the homogeneous disordered state in two-dimensional systems with uniaxially anisotropic self-propulsion. Using hydrodynamic arguments, we propose that the density correlation and polarity correlation generically exhibit power-law decay with distinct exponents (−2 and −4, respectively) through the coupling of density and polarity. Simulations of self-propelled lattice gas models indeed show the predicted power-law correlations, regardless of whether the interaction type is repulsion or alignment. Further, by mapping the model to a two-component boson system and employing non-Hermitian perturbation theory, we obtain the analytical expression for the structure factors, the Fourier transform of the correlation functions. This reveals that even the first order of the interaction strength induces the power-law correlations. Published by the American Physical Society 2024

Histidine Kinase QseC in Glaesserella parasuis Enhances the Secretion of Proinflammatory Cytokines by Macrophages via the p38 and NF-κB Signaling Pathways.

The qseC gene is a two-component system that encodes a histidine protein kinase and is highly conserved among different Glaesserella parasuis strains. In this study, we used qRT-PCR and enzyme-linked immunosorbent assay to confirm that Toll-like receptor 4 (TLR4) plays a role in the expression of proinflammatory cytokines interleukin (IL)-1β and IL-6 by stimulating RAW 264.7 macrophages with QseC. Furthermore, we revealed that blocking the p38 and NF-κB pathways that regulate signaling can significantly reduce the production of proinflammatory cytokines induced by QseC. In summary, our data suggest that QseC is a novel proinflammatory mediator that induces TLR4-dependent proinflammatory activity in RAW 264.7 macrophages through the p38 and NF-κB pathways.

Two-Component Signaling System RegAB Represses Pseudomonas syringae pv. actinidiae T3SS by Directly Binding to the promoter of hrpRS1

Kiwifruit bacterial canker, caused by Pseudomonas syringae pv. actinidiae (Psa), is a significant threat to the kiwifruit industry. The two-component signaling systems (TCSs) play a crucial role in regulating the virulence of Pseudomonas syringae (P. syringae), yet their specific function in Psa remains largely unclear. In this study, we found that disrupting the TCS RegAB (encoded by Psa_802/Psa_803) resulted in a notable increase in the pathogenicity of Pseudomonas syringae pv. actinidiae M228 (Psa M228) in host plant and hypersensitive reaction (HR) in nonhost plant. Through comparative transcriptome analysis of the Psa M228 wild-type strain and the regA mutant, we identified the pivotal role of RegA/B in controlling various physiological pathways, including the Type III secretion system (T3SS), a key determinant of Psa virulence. Additionally, we discovered that the RegA does have binding sites in the promoter region of the hrpR/S, and the transcriptional level of the hrpR and other T3SS-related genes increased in the regA deletion strain relative to the Psa M228 wild-type. The DNA-binding affinity of RegA, and therefore the repressor function, is enhanced by its phosphorylation. Our findings unveil the function of TCS RegAB and the regulatory mechanism of T3SS by RegAB in Psa, highlighting the diverse functions of the RegAB system.

Identification of potential inhibitors against Corynebacterium diphtheriae MtrA response regulator protein; an in-silico drug discovery approach

Corynebacterium diphtheriae is a multi-drug resistant bacteria responsible for the life-threatening respiratory illness, diphtheria which can lead to severe Nervous system disorders, mainly infecting the lungs, heart, and kidneys if left untreated. In the current study, Corynebacterium diphtheriae MtrA response regulator protein was targeted, which regulates a two-component system of bacterial pathogenesis, and initiates DNA replication and cell division. In the current study a computational approach have been described for drug development against C. diphtheriae infections by inhibiting MtrA protein by small molecules acting as potential inhibitors against it. Molecular docking analysis of the equilibrated MtrA protein revealed compound-0.2970, compound-0.3029, and compound-0.3016 from Asinex Library as the promising inhibitors based on their lowest binding energies (−9.8 kJ/mol, −9.2 kJ/mol, and −8.9 kJ/mol), highest gold scores (40.53, 47.41, and 48.41), drug-likeness and pharmacokinetic properties. The MD simulation studies of the identified top-ranked inhibitors at 100 ns elucidated the system stability and fluctuations in the binding pocket of MtrA protein. Molecular Dynamics Simulations of the top three docked complexes further revealed that the standard binding pocket was retained ensuring the system stability. The rearrangements of H-bonds, van der Waals, pi-pi, and solid hydrophobic interactions were also observed. The binding free energy calculations (MM/PBSA and MM/GBSA) suggested a fundamental binding capability of the ligand to the target receptor MtrA. Therefore, the current study has provided excellent candidates acting as potent inhibitors for developing therapeutic drugs against C. diphtheriae infections. However, in vivo and in vitro animal experiments and accurate clinical trials are needed to validate the potential inhibitory effect of these compounds.

Molecular dynamics study of shale oil adsorption and diffusion behavior in reservoir nanopores: Impact of hydrocarbon composition and surface type

Understanding shale oil adsorption in reservoir nanopores is essential for efficient extraction. This study used MD simulations to analyze the adsorption and diffusion of two- and multi-component hydrocarbons (Aromatics, Alkanes, Resin) on various shale surfaces (Calcite, Montmorillonite, Quartzite, Organic) at 353 K and 25 MPa. Hydrocarbons formed a bilayer adsorption structure comprising a high-concentration adsorption layer (L1, 0.35–0.90 g/cm3) and a low concentration weak adsorption layer (L2), with adsorption density ranked as Resin > Aromatics > Alkanes. Reservoir surfaces were classified as ionic (e.g., calcite, montmorillonite) and non-ionic (e.g., quartz, graphite), and polar hydrocarbons exhibited higher adsorption densities and energies on ionic surfaces due to combined electrostatic and van der Waals interactions, while non-ionic surfaces showed smaller adsorption differences. For multicomponent hydrocarbons, adsorption layer densities followed the order: graphite > MMT-SiO > quartz > calcite > MMT-Na, with competitive adsorption observed. The polar component exhibited a greater adsorption advantage on the calcite, MMT-SiO side and graphite surfaces due to electrostatic interactions and π-π interactions, and a lesser advantage on the MMT-Na side and quartz surfaces. Hydrocarbon diffusivity was influenced by molecular mass and polarity and ordered as Alkanes > Aromatics ≫ Resin. Polar molecules had a weaker diffusion than nonpolar molecules at similar molecular masses. Among the multicomponent hydrocarbons, the self-diffusion coefficient (Self-D) of Resin increased, while that of lighter components decreased compared to two-component systems. These findings offer strategies for improving shale oil recovery by tailoring injection fluids to reservoir types, anionic surfactants or chelating agents may be used to reduce electrostatic interactions in carbonate and clay reservoirs, while nonionic surfactants may be more effective in quartz reservoirs.

How Does a Low Surface Brightness Galaxy Form Spiral Arms?

The formation and evolution of spiral arms in low surface brightness galaxies (LSBs) are not well understood. We study the dynamics of spiral arms in two prototypical LSBs, FGC 568-VI and FGC 568-01, using both analytical models and N-body + hydrodynamical simulations. We first consider the disk as a two-component system of gravitationally coupled stars and gas in the force field of a spherical dark matter halo, subjected to local, nonaxisymmetric perturbations. However, no local spirals are formed. We next assume the disk to be a one-component system of stars in the net gravitational potential of a galaxy with a spherical dark matter halo perturbed by a global m = 2 instability. In this case, the growth time for spiral formation was low, equal to 0.78 and 0.96 Gyr, respectively, corresponding to a few dynamical times of the galaxies. Finally, we simulate the LSBs using the N-body + hydrodynamical simulation code RAMSES. Our results show that a quadrupolar field associated with an oblate halo with an axial ratio of 0.7 is necessary to drive a long-lived global spiral in the LSB disks. Further, feedback corresponding to a supernova mass fraction of ∼0.05 is essential to comply with the observed stellar surface density. The simulated spirals survive for about 10 dynamical times and the average pattern speed lies between 10 and 15 km s−1 kpc−1. The spiral arms thus formed are therefore a transient global pattern driven by the tidal field of the oblate dark matter halo.

A condition-based maintenance policy for a two-component balanced system with dependent degradation processes

Preventive maintenance of balanced systems has garnered increasing research attention due to its significance in production and servicing processes. This paper investigates the optimization problem of a condition-based maintenance policy for a two-component balanced system with dependent degradation processes. The system’s degradation follows a bivariate gamma process. Once the degradation level of one component exceeds a critical value, the system fails and triggers an immediate corrective replacement. Moreover, if the degradation difference between two components exceeds a threshold, the system is in an unbalanced state, which incurs a penalty cost. Periodic inspections are implemented to reveal the degradation of the system. At each inspection epoch, the decision-maker chooses an action among do-nothing, repair, and preventive replacement. Different from previous research, a repair action does not reduce the degradation levels of either component but increases the degradation level of the lower one to rebalance the system. The objective is to determine the optimal condition-based maintenance policy that minimizes the long-run average cost rate. The optimization problem is analyzed in a semi-Markov decision process framework. A policy-iteration dynamic programming algorithm is developed to derive the optimal policy. A numerical example is presented to illustrate the effectiveness of the proposed approach.

Polymyxin resistance in Enterobacter cloacae complex in Brazil: phenotypic and molecular characterization.

Enterobacter cloacae complex isolates have been reported as an important nosocomial multidrug resistance pathogen. In the present study, we investigated antimicrobial susceptibility and the colistin-resistance rates,their genetic determinants and clonality among clinical E. cloacae complex isolates from different Brazilian states. For this, an initial screening was carried out on 94 clinical isolates of E. clocacae complex received between 2016 and 2018 by LAPIH-FIOCRUZ, using EMB plates containing 4μg/mL of colistin, followed MIC determination, resulting in the selection of 26 colistin-resistant isolates from the complex. The presence of carbapenemases encoding genes (blaKPC, blaNDM and blaOXA-48), plasmidial genes for resistance to polymyxins (mcr1-9) and mutations in chromosomal genes (pmrA, pmrB, phoP and phoQ) described as associated with resistance to polymyxin were screened by PCR and DNA sequencing. Finally, the hsp60 gene was sequenced to identify species of the E. cloacae complex and genetic diversity was evaluated by PFGE and MLST. The results have shown that among 94 E. cloacae complex isolates, 19 (20.2%) were colistin-resistant. The resistant strains exhibited MIC ranging from 4 to 128µg / mL and E. hormaechei subsp. steigerwaltii was the prevalent species in the complex (31,6%), followed by E. cloacae subsp. cloacae (26,3%). The antimicrobials with the highest susceptibility rate were gentamicin (21%) and tigecycline (26%). Carbapenemases encoding genes (blaKPC n = 5, blaNDM n = 1) were detected in 6 isolates and mcr-9 in one. Among the modifications found in PmrA, PmrB, PhoP e PhoQ (two-component regulatory system), only the S175I substitution in PmrB found in E. cloacae subsp cloacae isolates were considered deleterious (according to the prediction of PROVEAN). By PFGE, 13 profiles were found among E. cloacae complex isolates, with EcD the most frequent. Furthermore, by MLST 10 ST's, and 1 new ST, were identified in E. cloacae. In conclusion, no prevalence of clones or association among carbapenemase production and polymyxin resistance was found between the E. cloacae. Thereby, the results suggest that the increased polymyxin-resistance is related to the selective pressure exerted by the indiscriminate use in hospitals. Lastly, this study highlights the urgent need to elucidate the mechanism involved in the resistance to polymyxin in the E. cloacae complex and the development of measures to control and prevent infections caused by these multiresistant bacteria.

The presence of differentiated C2C12 muscle cells enhances toxin production and growth by Clostridium perfringens type A strain ATCC3624

ABSTRACT Clostridium perfringens type A causes gas gangrene, which involves muscle infection. Both alpha toxin (PLC), encoded by the plc gene, and perfringolysin O (PFO), encoded by the pfoA gene, are important when type A strains cause gas gangrene in a mouse model. This study used the differentiated C2C12 muscle cell line to test the hypothesis that one or both of those toxins contributes to gas gangrene pathogenesis by releasing growth nutrients from muscle cells. RT-qPCR analyses showed that the presence of differentiated C2C12 cells induces C. perfringens type A strain ATCC3624 to upregulate plc and pfoA expression, as well as increase expression of several regulatory genes, including virS/R, agrB/D, and eutV/W. The VirS/R two component regulatory system (TCRS) and its coupled Agr-like quorum sensing system, along with the EutV/W TCRS (which regulates expression of genes involved in ethanolamine [EA] utilization), were shown to mediate the C2C12 cell-induced increase in plc and pfoA expression. EA was demonstrated to increase toxin gene expression. ATCC3624 growth increased in the presence of differentiated C2C12 muscle cells and this effect was shown to involve both PFO and PLC. Those membrane-active toxins were each cytotoxic for differentiated C2C12 cells, suggesting they support ATCC3624 growth by releasing nutrients from differentiated C2C12 cells. These findings support a model where, during gas gangrene, increased production of PFO and PLC in the presence of muscle cells causes more damage to those host cells, which release nutrients like EA that are then used to support C. perfringens growth in muscle.

Time-Dependent Color-Changing Room-Temperature Phosphorescence Materials with Mutual Achievement between Guest and Host Molecules.

Host-guest doping strategy has gradually become the mainstream in constructing organic room-temperature phosphorescence (RTP) materials. The two-component doped system typically emits monochromatic phosphorescence dominated by the guest molecule, which also means that the intrinsic phosphorescence emission of the host molecule is not well utilized. In this work, a time-dependent color-changing RTP material is constructed based on host-guest doped system, in which the initial yellow phosphorescence stems from the isoquinoline-pyrazole guest and the final cyan phosphorescence originates from the intrinsic emission of the polymer host. The phenomenon of the strong interaction between host and guest molecules leading to their respective intrinsic phosphorescence provides new design inspiration for designing and developing two-component doped materials with RTP properties of color variation over time.

Adsorption of Selected Herbicides on Activated Carbon from Single- and Multi-Component Systems-Error Analysis in Isotherm Measurements.

The aim of this study is to examine the influence of various factors on the precision and repeatability of the experimental determination of herbicide adsorption isotherms. Studies were conducted for the activated carbon RIB as an adsorbent and three herbicides as adsorbates: 2,4-dichlorophenoxyacetic acid (2,4-D), 4-chlorophenoxyacetic acid (4-CPA), and 3-chlorophenoxypropionic acid (3-CPP). The herbicide adsorption process was carried out in single-component and multi-component modes (the herbicide was adsorbed in the presence of an accompanying substance, i.e., 4-nitroaniline (4-NA)). Due to the significant contribution of the competition phenomenon in the adsorption process, which is important, e.g., in multi-component environmental systems, a qualitative and quantitative analysis of herbicide adsorption in the presence of a competing substance was presented. This work presents, among other things, the influence of adsorbent heterogeneity (grain size) on measurement uncertainties. The spread of standard deviations for solutions requiring dilution during spectrophotometric measurements was discussed, indicating that dilutions contribute to increasing measurement uncertainties. The heterogeneity parameters of the Freundlich equation for the studied adsorption systems were analyzed; the 2,4-D/RIB system was indicated as the most energetically heterogeneous. Differentiation of the experimental conditions (pH, temperature) allowed us to assess their impact on the efficiency and mechanism of adsorption. A high repeatability of experimental isotherms was obtained for the multi-component system. The accuracy of quantitative determination of equilibrium concentrations for the tested two-component systems was assessed based on the measured UV-Vis spectra, and the adsorption of herbicides from single- and multi-component systems was compared.

Functional connexion of bacterioferritin in antibiotic production and morphological differentiation in Streptomyces coelicolor

BackgroundSeveral two-component systems of Streptomyces coelicolor, a model organism used for studying antibiotic production in Streptomyces, affect the expression of the bfr (SCO2113) gene that encodes a bacterioferritin, a protein involved in iron storage. In this work, we have studied the effect of the deletion mutant ∆bfr in S. coelicolor.ResultsThe ∆bfr mutant exhibits a delay in morphological differentiation and produces a lesser amount of the two pigmented antibiotics (actinorhodin and undecylprodigiosin) compared to the wild type on complex media. The effect of iron in minimal medium was tested in the wild type and ∆bfr mutant. Consequently, we also observed different levels of production of the two pigmented antibiotics between the two strains, depending on the iron concentration and the medium (solid or liquid) used. Contrary to expectations, no differences in intracellular iron concentration were detected between the wild type and ∆bfr mutant. However, a higher level of reactive oxygen species in the ∆bfr mutant and a higher tolerance to oxidative stress were observed. Proteomic analysis showed no variation in iron response proteins, but there was a lower abundance of proteins related to actinorhodin and ribosomal proteins, as well as others related to secondary metabolite production and differentiation. Additionally, a higher abundance of proteins related to various types of stress, such as respiration and hypoxia among others, was also revealed. Data are available via ProteomeXchange with identifier PXD050869.ConclusionThis bacterioferritin in S. coelicolor (Bfr) is a new element in the complex regulation of secondary metabolism in S. coelicolor and, additionally, iron acts as a signal to modulate the biosynthesis of active molecules. Our model proposes an interaction between Bfr and iron-containing regulatory proteins. Thus, identifying these interactions would provide new information for improving antibiotic production in Streptomyces.

The Hydrogen-Bond Continuum in the Salt/Cocrystal Systems of Quinoline and Chloro-Nitrobenzoic Acids.

This study investigates the hydrogen-bond geometry in six two-component solid systems composed of quinoline and chloro-nitrobenzoic acids. New X-ray diffraction studies were conducted using both the conventional independent-atom model and the more recent Hirshfeld atom-refinement method, with the latter providing precise hydrogen-atom positions. The systems can be divided into salts (the hydrogen atom transferred to the quinoline nitrogen), cocrystals (the hydrogen atom retained by the acid), and intermediate structures. Solid-state NMR experiments corroborated the X-ray diffraction-derived H-N distances. DFT calculations, using five functionals including hybrid B3LYP and PBE0, showed varying energy profiles for the hydrogen bonds, with notable differences across functionals. These calculations revealed different preferences for salt or cocrystal structures, depending on the functional used. Path-integral molecular dynamics simulations incorporating nuclear quantum effects demonstrated significant hydrogen-atom delocalization, forming a hydrogen-bond continuum, and provided average N-H distances in excellent agreement with experimental results. This comprehensive experimental and theoretical approach highlights the complexity of multicomponent solids. The study emphasizes that the classification into salts or cocrystals is frequently inadequate, as the hydrogen atom is often significantly delocalized in the hydrogen bond. This insight is crucial for understanding and predicting the behavior of such systems in pharmaceutical applications.