Search Results (146)

Curli fimbriae are a major component of biofilm formation in Escherichia coli, and their expression is regulated by numerous transcription factors and small regulatory RNAs (sRNAs). The RcsD-RcsC-RcsB phosphorelay system, which is involved in the envelope stress response, plays a role in this regulation. In this study, we report that DNase-I footprinting analysis revealed that the response regulator RcsB interacts with the −31 to +53 region of the promoter region of csgD, which encodes a major regulator of biofilm formation, and thus contributes to its transcriptional repression. Additionally, overexpression of RcsB or RcsB D56A that could not be phosphorylated by the histidine kinases RcsC and D both significantly reduced csgD expression and suppressed Curli formation. This indicates that the phosphorylation of RcsB has an insignificant impact on its affinity for its operator sites. Furthermore, we confirm that RcsB binds cooperatively to the csgD promoter region in the presence of the nucleoid-associated protein H-NS. Our study also confirms that RcsB positively regulates the expression of an sRNA, RprA, which is known to reduce mRNA csgD mRNA translation RprA via its binding to the 5′-untranslated region (UTR) of csgD. These findings indicate that, in E. coli, the RcsBCD system suppresses csgD expression through both direct transcriptional repression by the regulator RcsB and translational repression by the sRNA RprA. Full article

Protein kinases and phosphatases are essential for post-translational regulation, enabling bacteria to adapt to environmental stresses and modulate virulence. While prior reviews have broadly covered their roles in stress response, antibiotic resistance, and virulence, this article updates specifically on the roles of histidine kinases (HKs) and serine/threonine kinases (STKs) in mediating phage-bacteria interactions. A key aspect is phage-encoded kinases, which hijack bacterial signalling by phosphorylating and disrupting host processes to promote infection. Despite their importance, significant gaps remain in understanding these regulatory networks. This microreview highlights both the unresolved mechanisms and the therapeutic potential of targeting kinase pathways—for instance, by disrupting phage evasion strategies or enhancing phage-based antimicrobial therapies. Full article

Plant-derived materials from Salvia officinalis L. (sage) have demonstrated significant antimicrobial potential when applied during fresh cheese production. In this study, the mechanism of action of sage components against Listeria monocytogenes, Escherichia coli, and Staphylococcus aureus was investigated through the development of predictive models that describe the influence of key parameters on antimicrobial efficacy. Molecular modeling techniques were employed to identify the major constituents responsible for the observed inhibitory activity. Epirosmanol, carvacrol, limonene, and thymol were identified as the primary compounds contributing to the antimicrobial effects during cheese production. The highest weighted predicted binding energy was observed for thymol against the KdpD histidine kinase from Staphylococcus aureus, with a value of −33.93 kcal/mol. To predict the binding affinity per unit mass of these sage-derived compounds against the target pathogens, machine learning models—including Artificial Neural Networks (ANN), Support Vector Machines (SVM), and Boosted Trees Regression (BTR)—were developed and evaluated. Among these, the ANN model demonstrated the highest predictive accuracy and robustness, showing minimal bias and a strong coefficient of determination (R² = 0.934). These findings underscore the value of integrating molecular modeling and machine learning approaches for the identification of bioactive compounds in functional food systems. Full article

Salinity stress poses a major challenge to agricultural productivity worldwide, including for pumpkin, a globally cultivated vegetable crop with great economic value. To deal with salt stress, plants exhibit an array of responses such as changes in their root system architecture. However, the root phenotype and gene expression of pumpkin in response to different concentrations of NaCl remains unclear. To this end, this study evaluated the effects of salinity stress on root architecture in C. moschata (Cmo-1, Cmo-2 and Cmo-3) and C. maxima (Cma-1, Cma-2 and Cma-3), as well as their hybrids of C. moschata and C. maxima (Ch-1, Ch-2 and Ch-3) at the germination and seedling stages. The results showed that the total root length and the number of root tips decreased by more than 10% and 5%, respectively, under 180 mM NaCl conditions compared to those under the 0 mM NaCl conditions. In contrast, the total root length and the number of root tips were increased or decreased under 60 mM NaCl conditions. Meanwhile, salt stress was considered severe when treated with more than 120 mM NaCl, which could be used to evaluate the salt tolerance of the germplasm resources of pumpkin. In addition, the transcriptional changes in the roots of both Cmo-3 and Cma-2 under salt stress were analyzed via RNA-sequencing. We found 4299 and 2141 differential expression genes (DEGs) in Cmo-3 and Cma-2, respectively. Plant hormone signal transduction, Phenylpropanoid biosynthesis and the MAPK signaling pathway were found to be the significant KEGG pathways. The expression of ARF (auxin response factor), B-ARR (type-B response regulator) and PYR (pyrabactin resistance)/PYL (PYR-LIKE) genes was downregulated by NaCl treatment. In contrast, the expression of SnRK2 (sucrose non-fermenting-1-related protein kinase 2) and AHP (histidine-containing phosphotransmitter) genes was downregulated in Cmo-3 and upregulated in Cma-2. These findings will help us better understand the mechanisms of salt tolerance in pumpkins and potentially provide insight into enhancing salt tolerance in crop plants. Full article

The plant hormones cytokinins are a class of heterogeneous active compounds that control multiple aspects of development and physiology. Among cytokinins, trans-zeatin (tZ), the most abundant cytokinin, has been extensively studied in relation to its effects on development, and it plays a key role in promoting cell differentiation. In analogy with tZ, here we demonstrate that dihydrozeatin (DHZ) controls (root) development by promoting cell differentiation. By means of pharmacological and genetic analysis, we demonstrate that DHZ is specifically and uniquely perceived by the histidine kinase (HK) receptor AHK3, and that this interaction is sufficient to promote cell differentiation in the root meristem via activation of the transcription factors ARABIDOPSIS RESPONSE REGULATOR 1, 12, and 11. We also show that DHZ and tZ activity might be conserved among plants. Our results support the idea that different types of cytokinins act via specific receptors to exert their roles and suggest new approaches to study their activity in differentiation. Full article

The multistep phosphorelay (MSP) is a conserved signaling system that allows plants to sense and respond to a variety of cues under rapidly changing environmental conditions. The MSP system comprises three main protein types: sensor histidine kinases, phosphotransmitters, and response regulators. There are numerous signaling pathways that use, in whole or in part, this set of proteins to transduce diverse signals. Among them, the cytokinin signal transduction system is the best-studied pathway, which utilizes the entire MSP cascade. Focusing on this system, we review here protein–protein interaction of MSP components that are not directly related to cytokinin signaling. These interactions are likely to play an essential role in hormonal crosstalk and may be promising targets for fine-tuning plant development. In addition, in light of recent advances in the study of cytokinin signaling, we discuss new insights into the putative molecular mechanisms that mediate the pleiotropic action of cytokinins and provide specificity for distinct MSP signals. A detailed network of known non-canonical protein–protein interactions related to cytokinin signaling was demonstrated. Full article

Bacterial communities in diverse environmental niches respond to various external stimuli for survival. A primary means of communication between bacterial cells involves one-component (OC) and two-component signal transduction systems (TCSs). These systems are key for sensing environmental changes and regulating bacterial physiology. TCSs, which are the more complex of the two, consist of a sensor histidine kinase for receiving an external input and a response regulator to convey changes in bacterial cell physiology. For numerous reasons, TCSs have emerged as significant targets for antibacterial drug design due to their role in regulating expression level, bacterial viability, growth, and virulence. Diverse studies have shown the molecular mechanisms by which TCSs regulate virulence and antibiotic resistance in pathogenic bacteria. In this study, we performed a thorough analysis of the data from multiple public databases to assemble a comprehensive catalog of the principal detection systems present in both the non-pathogenic Pseudomonas putida KT2440 and the pathogenic Pseudomonas aeruginosa PAO1 strains. Additionally, we conducted a sequence analysis of regulatory elements associated with transcriptional proteins. These were classified into regulatory families based on Helix-turn-Helix (HTH) protein domain information, a common structural motif for DNA-binding proteins. Moreover, we highlight the function of bacterial TCSs and their involvement in functions essential for bacterial survival and virulence. This comparison aims to identify novel targets that can be exploited for the development of advanced biotherapeutic strategies, potentially leading to new treatments for bacterial infections. Full article

The motility and chemotaxis of Vibrio cholerae, the bacterial pathogen responsible for cholera, play crucial roles in both environmental survival and infection. Understanding their molecular mechanisms is therefore essential not only for fundamental biology but also for infection control and therapeutic development. The bacterium’s sheathed, polar flagellum—its motility organelle—is powered by a sodium-driven motor. This motor’s rotation is regulated by the chemotaxis (Che) signaling system, with a histidine kinase, CheA, and a response regulator, CheY, serving as the central processing unit. However, V. cholerae possesses two additional, parallel Che signaling systems whose physiological functions remain unclear. Furthermore, the bacterium harbors over 40 receptors/transducers that interact with CheA homologs, forming a complex regulatory network likely adapted to diverse environmental cues. Despite significant progress, many aspects of these systems remain to be elucidated. Here, we summarize the current understanding to facilitate future research. Full article

Background: Due to the widespread use of broad-spectrum antibiotics, the problem of antibiotic resistance has become an increasingly serious global threat. One of the key mechanisms of Escherichia coli resistance to beta-lactam antibiotics is the production of beta-lactamase enzymes, which poses a dilemma for clinicians in selecting antibiotics when faced with resistant bacterial infections. However, research on the reversal of bacterial resistance is limited. Methods: This study involved the preparation of Iris tectorum extract and detection of its effects on antibiotics sensitivity, extended-spectrum beta-lactamase (ESBL) gene expression, and histidine kinase phosphorylation levels in β-lactam antibiotic-resistant Escherichia coli. Additionally, analyses of the active ingredients of Iris tectorum extract were conducted with a liquid chromatography–mass spectrometer, and the binding sites were predicted by molecular docking. Results: Iris tectorum extract could restore the sensitivity of Escherichia coli to beta-lactam antibiotics and reduce the expression levels of ESBL genes and histidine phosphorylation levels. The active ingredients of Iris tectorum extract may be irigenin and tectorigenin, and these two small molecules could bind to histidine kinase to inhibit phosphorylation. Conclusions: Iris tectorum extract may serve as an antibiotic adjuvant, restoring the sensitivity of antibiotic-resistant bacteria by inhibiting histidine kinase phosphorylation, thereby alleviating the problem of Escherichia coli resistance to β-lactam antibiotics. Full article

The purpose of this study was to investigate the physiological and biochemical changes of the hepatopancreas and intestinal microbial structure of Penaeus vannamei under various levels of carbonate alkalinity stress. After Penaeus vannamei (body length 14.24 ± 2.13 cm, body weight 26.31 ± 3.26 g) was subjected to 96 h carbonate alkalinity stress, the alkalinity stress levels were E8 (8 mmol/L), E18 (18 mmol/L) and E28 (28 mmol/L), respectively. The activity of antioxidant enzymes was determined by enzyme markers, and then the intestinal microorganisms of Penaeus vannamei were analyzed by high-throughput sequencing technology. The results showed that, under the stress of high carbonate alkalinity, the mortality rate of Penaeus vannamei was as high as 75%, and hepatopancreas cells showed obvious deformation, abnormal nuclear shapes, and serious cell vacuolation. Under high carbonate alkalinity stress, superoxide dismutase activity, catalase activity and glutathione peroxidase activity in the Penaeus vannamei hepatopancreas were significantly lower than those in control group (p < 0.05), and malondialdehyde content was significantly lower than that in the control group (p < 0.05). Alkaline phosphatase activity in the experimental group was significantly different from that in the control group (p < 0.05). Moreover, the 16SrDNA high-throughput sequencing results showed that the intestinal abundance of Proteobacteria in Penaeus vannamei was significantly decreased (p < 0.05) under high carbonate alkalinity stress, and the abundance of Bacteroides was significantly increased (p < 0.05). At the genus level, the abundance of Chrysobacteria was significantly increased (p < 0.05). The functional prediction results of COG and KEGG showed that the functional abundance of RNA polymerase sigma-70 factor is direct bacterial or plastid core RNA polymerase and is specific to promoter elements that are situated 10 and 35 base-pairs upstream of transcription-initiation points—in the high carbonate alkalinity treatment group, this was higher than that in the control group. The functional abundance of signal transduction histidine kinase was lower than that of the control group. The results of this study not only indicated that Penaeus vannamei cell structure would change and mortality would increase under high carbonate alkalinity culture environment, but they also analyzed the changes of the intestinal microbial structure under carbonate alkalinity stress. This study could provide theoretical reference for Penaeus vannamei saline–alkali land culture. Full article

The serine/threonine kinase CK2 (formerly known as casein kinase II) plays a crucial role in various CNS disorders and is highly expressed in various types of cancer. Therefore, inhibiting this key kinase could be promising for the treatment of these diseases. The CK2 holoenzyme is formed by the recruitment of two catalytically active CK2α and/or CK2α′ subunits by a regulatory CK2β dimer. Starting with the lead furocarbazole W16 (4) inhibiting the CK2α/CK2β interaction, analogous pyrrolocarbazoles were prepared and tested for their protein–protein interaction inhibition (PPII). The key step of the synthesis was a multicomponent Levy reaction of 2-(indolyl)acetate 6, benzaldehydes 7, and N-substituted maleimides 8. Targeted modifications were performed by the saponification of the tetracyclic ester 9a, followed by the coupling of the resulting acid 10 with diverse amines. The replacement of the O-atom of the lead furocarbazole 4 by an N-atom in pyrrolocarbazoles retained or even increased the inhibition of the CK2α/CK2β interaction. The large benzyloxazolidinyl moiety of 4 could be replaced by smaller N-substituents without the loss of the PPII. The introduction of larger substituents at the 2-position and/or at p-position of the phenyl moiety at the 10-position to increase the surface for the inhibition of the PPI did not enhance the inhibition of the CK2α/CK2β association. The strong inhibition of the CK2α/CK2β association by the histidine derivative (+)-20a (K_i = 6.1 µM) translated into a high inhibition of the kinase activity of the CK2 holoenzyme (CK2α₂β₂, IC₅₀ = 2.5 µM). Thus, 20a represents a novel lead compound inhibiting CK2 via the inhibition of the association of the CK2α and Ck2β subunits. Full article

Dysfunction in the prefrontal cortex can lead to cognitive inflexibility due to multifactorial causes as included cardiometabolic disorders, stress, inadequate diets, as well as an imbalance of the gut–brain axis microbiota. However, these risk factors have not been evaluated jointly. The purpose of this study was to evaluate the effect of physical stress (MS: Male Stress and FS: Female Stress) and high-fat diet (MD: Male Diet and FD: Female Diet) supplementation on the gut microbiota and cognitive flexibility. Methods: The study was performed on 47 mice, 30 male (M) and 17 female (F) BALBc, exposed to chronic stress physical (S) and high-fat diet (D). Cognitive flexibility was evaluated using the Attentional Set-Shifting Test (ASST) and the gut microbiota composition in terms of relative abundance (%) and alpha–beta diversity. Results: Results showed that S and D reduced cognitive flexibility in male and female mice (p < 0.0001). Significant changes occurred in Alistipes spp. (MM vs. MS:MD; p < 0.0001), Barnesiella spp. (FC vs. FS; p = 0.0002; FC vs. FD, p = 0.0033); Dorea spp. (MC vs. MD, p = 0.0008; MM vs. MD, p < 0.0001) and Lactobacillus spp. (MC vs. MD and FM vs. FS, p < 0.0001; FM vs. MD, p = 0.0393) genera among groups. Predictive functional analysis (QIIME2 and PICRUSt2) showed a significant increase in the expression of histidine kinase, alanine dehydrogenase, glutamine synthase, glutamate synthase, arginine succinyl synthase, and tryptophan synthase genes (p < 0.05), the latter being a precursor of serotonin (5-HT). Conclusions: Chronic physical stress and a high-fat diet modify cognitive flexibility and the composition and predictive function of the gut microbiota. Full article

Phenylalanine (Phe) is a potentially limiting amino acid for lactating cows. The mechanism by which Phe regulates milk protein synthesis remains unclear. The present study elucidates the mechanisms by which phenylalanine affects milk protein synthesis, amino acid utilization, and related signaling pathways in bovine mammary epithelial cells (BMECs). The BMECs were treated with five concentrations (0, 0.22, 0.44, 0.88, 1.76 mM, and serum free). Rapamycin inhibitors and RNA interference (RNAi) were used to inhibit the phosphorylation of the mammalian target of rapamycin (mTOR) signaling pathway and the expression of relevant amino acid transporters, respectively. The results showed that 4×Phe (0.88 mM) significantly increased (p < 0.05) both the mRNA and protein expression of α-casein (CSN1S1), β-casein (CSN2), and κ-casein (CSN3), as well as L-type amino acid transporter-1 (LAT1) mRNA expression. Protein expression and modification assays of mTOR-related proteins showed that 4×Phe could increase (p < 0.05) the expression of α-casein and eukaryotic initiation factor 4E-binding protein-1 (4EBP1) and tended to increase the expression of ribosomal protein S6 protein kinase (S6K1, p = 0.054). The general control nonderepressible 2 (GCN2) signaling pathway factor, eukaryotic initiation factor 2 (eIF2α), was downregulated by 4×Phe treatment (p < 0.05). The rapamycin inhibition test showed that Phe regulated casein synthesis via the mTOR signaling pathway. RNAi experiments showed that LAT1 mediated the entry of Phe into cells. Moreover, 4×Phe treatment tended to decrease (0.05 < p < 0.10) the consumption of valine, leucine, histidine, tyrosine, cysteine, alanine, asparagine, and serine in the medium. Collectively, phenylalanine enhanced α-casein synthesis by regulating the phosphorylation of 4EBP1 and eIF2α and promoting the formation of the mTOR-centered casein translation initiation complex. Full article

Two-component systems (TCS) of Salmonella enterica serovar Enteritidis are composed of a histidine kinase and a response regulator (RR) and represent a critical mechanism by which bacteria develop resistance to environmental stress. Here, we characterized the functions of RRs in TCS in the formation of stress tolerance, motility and biofilm using twenty-six S. Enteritidis RR-encoding gene deletion mutants. The viability results unraveled their essential roles in resistance to elevated temperature (GlrR), pH alterations (GlrR, TctD, YedW, ArcA and YehT), high salt (PhoB, BaeR, CpxR, PhoP, UvrY and TctD), oxidative stress (PhoB, YedW, BaeR, ArcA, PhoP, UvrY, PgtA and QseB) and motility (ArcA, GlnG, PgtA, PhoB, UhpA, OmpR, UvrY and QseB) of S. Enteritidis. The results of the crystal violet staining, microscopy observation and Congo red binding assays demonstrated that the absence of ArcA, GlnG, PhoP, OmpR, ZraR or SsrB in S. Enteritidis led to a reduction in biofilms and an impairment in red/dry/rough macrocolony formation, whereas the absence of UvrY exhibited an increase in biofilms and formed a brown/smooth/sticky macrocolony. The results indicated the regulatory effects of these RRs on the production of biofilm matrix, curli fimbriae and cellulose. Our findings yielded insights into the role of TCSs, making them a promising target for combating S. Enteritidis. Full article

Background: Autosomal recessive inherited pathogenetic variants in the histidine triad nucleotide-binding protein 1 (HINT1) gene are responsible for an axonal Charcot-Marie-Tooth neuropathy associated with neuromyotonia, a phenomenon resulting from peripheral nerve hyperexcitability that causes a spontaneous muscle activity such as persistent muscle contraction, impaired relaxation and myokymias. Methods: Herein, we describe two brothers in whom biallelic HINT1 variants were identified following a multidisciplinary approach. Results: The younger brother came to our attention for clinical evaluation of moderate intellectual disability, language developmental delay, and some behavioral issues. His elder brother presented mild intellectual disability, hyperactivity, tiptoe walking, and gait ataxia. At first evaluation, motor impairment with frequent falls, pes cavus, and distal hyposthenia with reduced osteotendinous reflexes were found in both. Grip myotonic phenomenon was also noted. Blood tests revealed mildly elevated creatine kinase, and neurophysiology investigations revealed predominantly axonal polyneuropathy. Muscle MRI highlighted fibro-adipose infiltration, prevalent in the lower limbs. Gene panel testing detected a heterozygous HINT1 variant (c.355C>T/p.(Arg119Trp)) on the paternal allele. A further in-depth analysis using Integrative Genomics Viewer and Optical Genome Mapping led us to identify an additional variant in HINT1 represented by a complex rearrangement located in the region 5′UTR-exon 1-intron 1, not previously described. Conclusions: This complex rearrangement could have been overlooked if the clinical picture had not been evaluated as a whole (from a clinical, neurophysiological, and neuroimaging point of view). Neuropsychiatric manifestations (intellectual disability, hyperactivity, etc.) are part of the picture of HINT1-related neuromyotonia. Full article