Cysteine Biosynthesis Research Articles

OPDA signaling channels resource (e-) allocations from photosynthetic ETC to plastid cysteine biosynthesis in defense activations.

A primary precursor of jasmonates 12-oxo-phytodienoic acid (OPDA) is an autonomous hormone signal that activates and fine-tunes plant defense responses, as well as growth and development. However, the architecture of its signaling circuits remains largely elusive. Here we describe that OPDA signaling drives photosynthetic reductant powers toward the plastid sulfur assimilations, incorporating sulfide into cysteine. Under stressed states, OPDA -accumulated in the chloroplasts- binds and promotes cyclophilin 20-3, an OPDA receptor, to transfer electrons from thioredoxin F2, an electron carrier in the photosynthesis reaction, to serine acetyltransferase 1 (SAT1). The charge carrier (H+, e-) then splits dimeric SAT1 trimers in half to signal the recruitment of dimeric O-acetylserine(thiol)lyase B, forming a hetero-oligomeric cysteine synthase complex (CSC). The CSC formation and its metabolic products (esp., glutathione) then coordinate redox-resolved retrograde signaling from the chloroplasts to the nucleus in adjusting OPDA-responsive gene expressions such as GLUTAREDOXIN 480 and CYTOCHROME P450, and actuating defense responses against various ecological constraints such as salinity and excess oxidants, as well as mechanical wounding. We thus conclude that OPDA signaling regulates a unique metabolic switch in channeling light input into outputs that fuel/shape a multitude of physiological processes, optimizing plant growth fitness and survival capacity under a range of environmental stress cues.

Evidence for a hydrogen sulfide-sensing E3 ligase in yeast.

In yeast, control of sulfur amino acid metabolism relies upon Met4, a transcription factor that activates the expression of a network of enzymes responsible for the biosynthesis of cysteine and methionine. In times of sulfur abundance, the activity of Met4 is repressed via ubiquitination by the SCFMet30 E3 ubiquitin ligase, but the mechanism by which the F-box protein Met30 senses sulfur status to tune its E3 ligase activity remains unresolved. Herein, we show that Met30 responds to flux through the trans-sulfuration pathway to regulate the MET gene transcriptional program. In particular, Met30 is responsive to the biological gas hydrogen sulfide, which is sufficient to induce ubiquitination of Met4 in vivo. Additionally, we identify important cysteine residues in Met30's WD-40 repeat region that sense the availability of sulfur in the cell. Our findings reveal how SCFMet30 dynamically senses the flow of sulfur metabolites through the trans-sulfuration pathway to regulate the synthesis of these special amino acids.

Engineering Plant Metabolism for Synthesizing Amino Acid Derivatives of Animal Origin Using a Synthetic Modular Approach.

The biosynthesis of amino acid derivatives of animal origin in plants represents a promising frontier in synthetic biology, offering a sustainable and eco-friendly approach to enhancing the nutritional value of plant-based diets. This study leverages the versatile capabilities of Nicotiana benthamiana as a transient expression system to test a synthetic modular framework for the production of creatine, carnosine, and taurine-compounds typically absent in plants but essential for human health. By designing and stacking specialized synthetic modules, we successfully redirected the plant metabolic flux toward the synthesis of these amino acid derivatives of animal origin. Our results revealed the expression of a standalone creatine module resulted in the production of 2.3 μg/g fresh weight of creatine in N. benthamiana leaves. Integrating two modules significantly carnosine yield increased by 3.8-fold and minimized the impact on plant amino acid metabolism compared to individual module application. Unexpectedly, introducing the taurine module caused a feedback-like inhibition of plant cysteine biosynthesis, revealing complex metabolic adjustments that can occur when introducing foreign pathways. Our findings underline the potential for employing plants as biofactories for the sustainable production of essential nutrients of animal origin.

Biofortifying multiple micronutrients and decreasing arsenic accumulation in rice grain simultaneously by expressing a mutant allele of OAS-TL gene.

Rice grains typically contain relatively high levels of toxic arsenic (As) but low levels of essential micronutrients. Biofortification of essential micronutrients while decreasing As accumulation in rice would benefit human nutrition and health. We generated transgenic rice expressing a gain-of-function mutant allele astol1 driven by the OsGPX1 promoter. astol1 encodes a plastid-localized O-acetylserine (thiol) lyase (OAS-TL) with Ser189Asn substitution (OsASTOL1S189N), which enhances cysteine biosynthesis by forming an indissociable cysteine synthase complex with its partner serine acetyltransferase (SAT). The effects on growth, As tolerance, and nutrient and As accumulation in rice grain were evaluated in hydroponic, pot and field experiments. The expression of OsASTOL1S189N in pOsGPX1::astol1 transgenic lines enhanced SAT activity, sulphate uptake, biosynthesis of cysteine, glutathione, phytochelatins and nicotianamine, and enhanced tolerance to As. The expression of OsASTOL1S189N decreased As accumulation while increased the accumulation of multiple macronutrients (especially sulphur, nitrogen and potassium) and micronutrients (especially zinc and selenium) in rice grain in a pot experiment and two field experiments, and had little effect on plant growth and grain yield. Our study provides a new strategy to genetically engineer rice to biofortify multiple essential nutrients, reducing As accumulation in rice grain and enhancing As tolerance simultaneously.

Revisiting oxygen toxicity: evolution and adaptation to superoxide in a SOD-deficient bacterial pathogen.

Defenses against oxidants are crucial for the virulence of pathogens, with superoxide scavenging enzymes (SOSEs) playing a vital role for most aerobes. However, our knowledge of superoxide adaptation primarily stems from the study of SOSE-encoding bacteria. Here, we investigated the evolution of a naturally SOSE-deficient pathogen ( Leptospira spp.), along with the alternative mechanisms it recruits to combat superoxide stress. We demonstrate that emergence of pathogenic Leptospira correlated with SOD loss, but that a long-lasting adaptation to superoxide remains possible. We reveal that cysteine and leucine biosynthesis are the most induced pathways in response to superoxide and demonstrate the importance of sulfur metabolism in superoxide adaptation in this SOSE-deficient model. We also propose cysteine oxidation as a key mediator of superoxide toxicity in the absence of SOSEs. This study challenges our conventional understanding of the oxygen toxicity theory and proposes a new model of superoxide adaptation through metabolic rewiring in bacteria.

Abstract B085: The HIF-2 transcription factor mediates resistance to ferroptosis in pancreatic adenocarcinoma

Abstract Ferroptosis is an iron-dependent form of cell death converging on lipid peroxidation, first identified by examining compounds with enhanced lethality to KRAS mutant cells. Two compounds widely used as ferroptosis inducers are erastin, which acts as an inhibitor of cystine import and thereby depletes cellular glutathione, and RSL-3, which inhibits glutathione peroxidase 4. Despite over 90% of pancreatic adenocarcinoma (PDAC) tumors harboring KRAS mutations, PDAC exhibits relative resistance to ferroptosis compared to other tumor types, and the mechanisms behind this resistance remain unclear. The pancreatic tumor environment is marked by severe hypoxia, due to poor vascularity and a dense fibrotic stroma, and so we hypothesized that hypoxia might mediate resistance to ferroptosis. Here we report that across a panel of human and murine PDAC cell lines, hypoxia induces resistance to both ferroptosis inducing agents, erastin and RSL-3. The effect of hypoxia was synergistic with exposure to pancreatic cancer tumor interstitial fluid, which induces a hypoxic-like gene expression profile even under normoxia and enhances hypoxic gene expression changes when combined with hypoxia. Our findings reveal that hypoxia-mediated resistance to ferroptosis is orchestrated by the hypoxia-inducible transcription factor HIF-2, as evidenced by its complete abolition in HIF-2 knockout cell lines, while the protective effect of hypoxia was maintained in HIF-1 knockout lines. RNA-seq analyses and chromatin immunoprecipitation studies (chIP) identified several HIF-2 target genes responsible for coordinating ferroptosis resistance mechanisms. Cysteine is a precursor for glutathione, and HIF-2 increased cystine import through upregulation of both components of the cystine-glutamate antiporter system Xc (SLC7A11 and SLC3A2) and increased cysteine biosynthesis via upregulation of transsulfuration pathway enzymes (CBS and CTH). In addition, HIF-2 upregulated Parkin, which we identify as a novel regulator of ferroptosis, thereby increasing mitophagy and decreasing reactive oxygen species. In vivo studies using human and murine PDAC xenograft models confirmed that HIF-2 knockout impaired tumor growth and increased susceptibility to the pro-ferroptotic agent sulfasalazine. Collectively, these data identify a mechanism by which PDAC evades ferroptosis and identifies a possible therapeutic strategy of combining HIF-2 inhibitors with pro-ferroptotic agents in pancreatic cancer. Citation Format: Maimon E Hubbi, Catherine Wang, Erin Hollander, Yasir Suhail, Kshitiz, Alexander Muir, Ben Z Stanger, Chi V Dang. The HIF-2 transcription factor mediates resistance to ferroptosis in pancreatic adenocarcinoma [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl_2):Abstract nr B085.

Structural damage and organelle destruction: Mechanisms of pseudolaric acid B against S. parasitica

This study aimed to investigate the potential of Chinese herbs in treating aquatic diseases. More particularly, the antibacterial properties and mechanisms of Chinese herbs and their monomers against Saprolegnia parasitica were investigated. In vitro antibacterial testing revealed that Cortex pseudolaricis exhibited significant antibacterial activity, with a minimum inhibitory concentration (MIC) of 0.98 mg/mL. The primary monomer responsible for this antibacterial effect was identified as pseudolaric acid B (PAB), with an MIC of 0.03 mg/mL. SEM and TEM analyses demonstrated that treatment with PAB resulted in structural damage to the cell wall and cell membrane of hyphae, leading to lysis of the cell wall and membrane of spores, organelle destruction, and vacuole formation within the cells. Analysis of the transcriptome and metabolome revealed that PAB disrupts amino acid, lipid, and nucleic acid metabolism in S. parasitica. This disruption impacts the biosynthesis and metabolism of various amino acids, including arginine, proline, glycine, serine, cysteine, methionine, glutamate, lysine, histidine, phenylalanine, tyrosine, and tryptophan. PAB also results in increased energy consumption and hindered energy generation in S. parasitica, as well as interference with the synthesis of membrane components such as DAG and phytosphingosine. Furthermore, PAB disrupts RNA, DNA, and ATP production in S. parasitica. Consequently, protein synthesis, energy supply, immune function and barrier structure in S. parasitica are weakened, and potentially leading to death. This study identifies potential antibacterial agents for environmentally friendly solutions for controlling fish saprolegniasis.

Impact of mineral and non-mineral sources of iron and sulfur on the metalloproteome of Methanosarcina barkeri.

Methanogens often inhabit sulfidic environments that favor the precipitation of transition metals such as iron (Fe) as metal sulfides, including mackinawite (FeS) and pyrite (FeS2). These metal sulfides have historically been considered biologically unavailable. Nonetheless, methanogens are commonly cultivated with sulfide (HS-) as a sulfur source, a condition that would be expected to favor metal precipitation and thus limit metal availability. Recent studies have shown that methanogens can access Fe and sulfur (S) from FeS and FeS2 to sustain growth. As such, medium supplied with FeS2 should lead to higher availability of transition metals when compared to medium supplied with HS-. Here, we examined how transition metal availability under sulfidic (i.e., cells provided with HS- as sole S source) versus non-sulfidic (cells provided with FeS2 as sole S source) conditions impact the metalloproteome of Methanosarcina barkeri Fusaro. To achieve this, we employed size exclusion chromatography coupled with inductively coupled plasma mass spectrometry and shotgun proteomics. Significant changes were observed in the composition and abundance of iron, cobalt, nickel, zinc, and molybdenum proteins. Among the differences were alterations in the stoichiometry and abundance of multisubunit protein complexes involved in methanogenesis and electron transport chains. Our data suggest that M. barkeri utilizes the minimal iron-sulfur cluster complex and canonical cysteine biosynthesis proteins when grown on FeS2 but uses the canonical Suf pathway in conjunction with the tRNA-Sep cysteine pathway for iron-sulfur cluster and cysteine biosynthesis under sulfidic growth conditions.IMPORTANCEProteins that catalyze biochemical reactions often require transition metals that can have a high affinity for sulfur, another required element for life. Thus, the availability of metals and sulfur are intertwined and can have large impacts on an organismismal biochemistry. Methanogens often occupy anoxic, sulfide-rich (euxinic) environments that favor the precipitation of transition metals as metal sulfides, thereby creating presumed metal limitation. Recently, several methanogens have been shown to acquire iron and sulfur from pyrite, an abundant iron-sulfide mineral that was traditionally considered to be unavailable to biology. The work presented here provides new insights into the distribution of metalloproteins, and metal uptake of Methanosarcina barkeri Fusaro grown under euxinic or pyritic growth conditions. Thorough characterizations of this methanogen under different metal and sulfur conditions increase our understanding of the influence of metal availability on methanogens, and presumably other anaerobes, that inhabit euxinic environments.

Discovering new mode-of-action pesticide leads inhibiting protein-protein interactions: example targeting plant O-acetylserine sulfhydrylase.

The widespread evolution of pesticide resistance poses a significant challenge to current agriculture, necessitating the discovery of molecules with new modes of action. Despite extensive efforts, no major molecules with new modes of action have been commercialized for decades. Most pesticides function by binding to specific pockets on target enzymes, enabling a single target site mutation to confer resistance. An alternative approach is the disruption of protein-protein interactions (PPI), which require complementary mutations on both interacting partners for resistance to occur. Thus, our aim is the discovery and design of small-molecule inhibitors that target the interface of the PPI complex of O-acetylserine sulfhydrylase (OASS) and serine acetyltransferase (SAT), key obligatory interacting plant enzymes involved in the biosynthesis of the amino acid cysteine. By employing in silico filtering techniques on a virtual library of 30 million small molecules, we identified initial hits capable of binding OASS and interfering with its interaction with a peptide derived from SAT with a half-maximal inhibitory concentration (IC50) of 34 μm. Subsequently, we conducted molecular chemical optimizations, generating an early lead molecule (PJ4) with an IC50 value of 4 μm. PJ4 successfully inhibited the germination of Arabidopsis thaliana seedlings and inhibited clover growth in a pre-emergence application at an effective concentration of 4.6 kg ha-1. These new compounds described herein can serve as promising leads for further optimization as herbicides with a new mode-of-action. This technology can be used for discovering new modes of action chemicals inhibiting all pest groups. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Epigenetic repression of de novo cysteine synthetases induces intra-cellular accumulation of cysteine in hepatocarcinoma by up-regulating the cystine uptake transporter xCT

BackgroundThe metabolic reprogramming of amino acids is critical for cancer cell growth and survival. Notably, intracellular accumulation of cysteine is often observed in various cancers, suggesting its potential role in alleviating the oxidative stress associated with rapid proliferation. The liver is the primary organ for cysteine biosynthesis, but much remains unknown about the metabolic alterations of cysteine and their mechanisms in hepatocellular carcinoma cells.MethodsRNA-seq data from patients with hepatocarcinoma were analyzed using the TNMplot database. The underlying mechanism of the oncogenic alteration of cysteine metabolism was studied in mice implanted with BNL 1ME A.7 R.1 hepatocarcinoma.ResultsDatabase analysis of patients with hepatocellular carcinoma revealed that the expression of enzymes involved in de novo cysteine synthesis was down-regulated accompanying with increased expression of the cystine uptake transporter xCT. Similar alterations in gene expression have also been observed in a syngeneic mouse model of hepatocarcinoma. The enhanced expression of DNA methyltransferase in murine hepatocarcinoma cells caused methylation of the upstream regions of cysteine synthesis genes, thereby repressing their expression. Conversely, suppression of de novo cysteine synthesis in healthy liver cells induced xCT expression by up-regulating the oxidative-stress response factor NRF2, indicating that reduced de novo cysteine synthesis repulsively increases cystine uptake via enhanced xCT expression, leading to intracellular cysteine accumulation. Furthermore, the pharmacological inhibition of xCT activity decreased intracellular cysteine levels and suppressed hepatocarcinoma tumor growth in mice.ConclusionsOur findings indicate an underlying mechanism of the oncogenic alteration of cysteine metabolism in hepatocarcinoma and highlight the efficacy of alteration of cysteine metabolism as a viable therapeutic target in cancer.

Overexpression of sesame O-acetylserine(thiol)lyase induces male sterility by delaying tapetum programmed cell death

Male sterile lines are key resources for hybrid seed production and for ensuring high varietal purity. However, the genes and mechanisms underlying sesame male sterility remain largely unknown. Hence, this study identified an O-acetylserine(thiol)lyase gene SiOASTL1 and functionally characterized its roles in inducing defective anther development. Spatiotemporal expression analysis revealed that SiOASTL1 is significantly (2.7 fold) up-regulated in sterile sesame anthers at the microspore stage compared with fertile ones. Sequence and phylogenetic analyses showed that SiOASTL1 is homologous to Arabidopsis OAS-TL plastid isoforms. We thus overexpressed SiOASTL1 in Arabidopsis to unravel its regulatory roles. Cytological observation revealed that SiOASTL1 overexpression transformed transgenic plants into male sterile lines arising at the microspore development stage. SiOASTL1 overexpression decreased cysteine biosynthesis and down-regulated the expression of the sporopollenin synthesis-related genes, including AtTKPR1, AtTKPR2, AtPKSA, and AtPKSB in transgenic Arabidopsis. Consequently, the tapetum programmed cell death (PCD) was delayed, resulting in the formation of defective pollen grains with irregular walls and empty cytoplasm. Our findings prove that the induction of SiOASTL1 expression disrupts pollen development and contributes to sesame male sterility. Moreover, these results suggest that genetic manipulation of SiOASTL1 expression may facilitate the development of new hybrid varieties in sesame and other crops.

The Structure of the LysR-type Transcriptional Regulator, CysB, Bound to the Inducer, N-acetylserine

In Escherichia coli and Salmonella typhimurium, cysteine biosynthesis requires the products of 20 or more cys genes co-ordinately regulated by CysB. Under conditions of sulphur limitation and in the presence of the inducer, N-acetylserine, CysB binds to cys promoters and activates the transcription of the downstream coding sequences. CysB is a homotetramer, comprising an N-terminal DNA binding domain (DBD) and a C-terminal effector binding domain (EBD). The crystal structure of a dimeric EBD fragment of CysB from Klebsiella aerogenes revealed a protein fold similar to that seen in Lac repressor but with a different symmetry in the dimer so that the mode of DNA binding was not apparent. To elucidate the subunit arrangement in the tetramer, we determined the crystal structure of intact CysB in complex with N-acetylserine. The tetramer has two subunit types that differ in the juxtaposition of their winged helix-turn-helix DNA binding domains with respect to the effector binding domain. In the assembly, the four EBDs form a core with the DNA binding domains arranged in pairs on the surface. N-acetylserine makes extensive polar interactions in an enclosed binding site, and its binding is accompanied by substantial conformational rearrangements of surrounding residues that are propagated to the protein surface where they appear to alter the arrangement of the DNA binding domains. The results are (i) discussed in relation to the extensive mutational data available for CysB and (ii) used to propose a structural mechanism of N-acetylserine induced CysB activation.

Advancements in inhibitors of crucial enzymes in the cysteine biosynthetic pathway: Serine acetyltransferase and O-acetylserine sulfhydrylase.

Infectious diseases have been jeopardized problem that threaten public health over a long period of time. The growing prevalence of drug-resistant pathogens and infectious cases have led to a decrease in the number of effective antibiotics, which highlights the urgent need for the development of new antibacterial agents. Serine acetyltransferase (SAT), also known as CysE in certain bacterial species, and O-acetylserine sulfhydrylase (OASS), also known as CysK in select bacteria, are indispensable enzymes within the cysteine biosynthesis pathway of various pathogenic microorganisms. These enzymes play a crucial role in the survival of these pathogens, making SAT and OASS promising targets for the development of novel anti-infective agents. In this comprehensive review, we present an introduction to the structure and function of SAT and OASS, along with an overview of existing inhibitors for SAT and OASS as potential antibacterial agents. Our primary focus is on elucidating the inhibitory activities, structure-activity relationships, and mechanisms of action of these inhibitors. Through this exploration, we aim to provide insights into promising strategies and prospects in the development of antibacterial agents that target these essential enzymes.

Metabolomic characterization of monoclonal antibody-producing Chinese hamster lung (CHL)-YN cells in glucose-controlled serum-free fed-batch operation.

The fast-growing Chinese hamster lung (CHL)-YN cell line was recently developed for monoclonal antibody production. In this study, we applied a serum-free fed-batch cultivation process to immunoglobulin (Ig)G1-producing CHL-YN cells, which were then used to design a dynamic glucose supply system to stabilize the extracellular glucose concentration based on glucose consumption. Glucose consumption of the cultures rapidly oscillated following three phases of glutamine metabolism: consumption, production, and re-consumption. Use of the dynamic glucose supply prolonged the viability of the CHL-YN-IgG1 cell cultures and increased IgG1 production. Liquid chromatography with tandem mass spectrometry-based target metabolomics analysis of the extracellular metabolites during the first glutamine shift was conducted to search for depleted compounds. The results suggest that the levels of four amino acids, namely arginine, aspartate, methionine, and serine, were sharply decreased in CHL-YN cells during glutamine production. Supporting evidence from metabolic and gene expression analyses also suggest that CHL-YN cells acquired ornithine- and cystathionine-production abilities that differed from those in Chinese hamster ovary-K1 cells, potentially leading to proline and cysteine biosynthesis.

Ethylene glycol is metabolized to ethanol and acetate and induces expression of bacterial microcompartments in Propionibacterium freudenreichii

Ethylene glycol (EG, 1,2-ethanediol) is a two-carbon dihydroxy alcohol that can be derived from fermentation of plant-derived xylose and arabinose and which can be formed during food fermentations. Here we show that Propionibacterium freudenreichii DSM 20271 is able to convert EG in anaerobic conditions to ethanol and acetate in almost equimolar amounts. The metabolism of EG led to a moderate increase of biomass, indicating its metabolism is energetically favourable. A proteomic analysis revealed EG induced expression of the pdu-cluster, which encodes a functional bacterial microcompartment (BMC) involved in the degradation of 1,2-propanediol, with the presence of BMCs confirmed using transmission electron microscopy. Cross-examination of the proteomes of 1,2-propanediol and EG grown cells revealed PDU BMC-expressing cells have elevated levels of DNA repair proteins and cysteine biosynthesis proteins. Cells grown in 1,2-propanediol and EG also showed enhanced resistance against acid and bile salt-induced stresses compared to lactate-grown cells. Our analysis of whole genome sequences of selected genomes of BMC-encoding microorganisms able to metabolize EG with acetaldehyde as intermediate indicate a potentially broad-distributed role of the pdu operon in metabolism of EG. Based on our results we conclude EG is metabolized to acetate and ethanol with acetaldehyde as intermediate within BMCs in P. freudenreichii.

Oceanobacillus picturae alleviates cadmium stress and promotes growth in soybean seedlings

Cadmium (Cd) is a heavy metal that significantly impacts human health and the environment. Microorganisms play a crucial role in reducing heavy metal stress in plants; however, the mechanisms by which microorganisms enhance plant tolerance to Cd stress and the interplay between plants and microorganisms under such stress remain unclear. In this study, Oceanobacillus picturae (O. picturae) was isolated for interaction with soybean seedlings under Cd stress. Results indicated that Cd treatment alone markedly inhibited soybean seedling growth. Conversely, inoculation with O. picturae significantly improved growth indices such as plant height, root length, and fresh weight, while also promoting recovery in soil physiological indicators and pH. Metabolomic and transcriptomic analyses identified 157 genes related to aspartic acid, cysteine, and flavonoid biosynthesis pathways. Sixty-three microbial species were significantly associated with metabolites in these pathways, including pathogenic, adversity-resistant, and bioconductive bacteria. This research experimentally demonstrates, for the first time, the growth-promoting effect of the O. picturae strain on soybean seedlings under non-stress conditions. It also highlights its role in enhancing root growth and reducing Cd accumulation in the roots under Cd stress. Additionally, through the utilization of untargeted metabolomics, metagenomics, and transcriptomics for a multi-omics analysis, we investigated the impact of O. picturae on the soil microbiome and its correlation with differential gene expression in plants. This innovative approach unveils the molecular mechanisms underlying O. picturae's promotion of root growth and adaptation to Cd stress.

Temporal dynamics of stress response in Halomonas elongata to NaCl shock: physiological, metabolomic, and transcriptomic insights

BackgroundThe halophilic bacterium Halomonas elongata is an industrially important strain for ectoine production, with high value and intense research focus. While existing studies primarily delve into the adaptive mechanisms of this bacterium under fixed salt concentrations, there is a notable dearth of attention regarding its response to fluctuating saline environments. Consequently, the stress response of H. elongata to salt shock remains inadequately understood.ResultsThis study investigated the stress response mechanism of H. elongata when exposed to NaCl shock at short- and long-time scales. Results showed that NaCl shock induced two major stresses, namely osmotic stress and oxidative stress. In response to the former, within the cell’s tolerable range (1–8% NaCl shock), H. elongata urgently balanced the surging osmotic pressure by uptaking sodium and potassium ions and augmenting intracellular amino acid pools, particularly glutamate and glutamine. However, ectoine content started to increase until 20 min post-shock, rapidly becoming the dominant osmoprotectant, and reaching the maximum productivity (1450 ± 99 mg/L/h). Transcriptomic data also confirmed the delayed response in ectoine biosynthesis, and we speculate that this might be attributed to an intracellular energy crisis caused by NaCl shock. In response to oxidative stress, transcription factor cysB was significantly upregulated, positively regulating the sulfur metabolism and cysteine biosynthesis. Furthermore, the upregulation of the crucial peroxidase gene (HELO_RS18165) and the simultaneous enhancement of peroxidase (POD) and catalase (CAT) activities collectively constitute the antioxidant defense in H. elongata following shock. When exceeding the tolerance threshold of H. elongata (1–13% NaCl shock), the sustained compromised energy status, resulting from the pronounced inhibition of the respiratory chain and ATP synthase, may be a crucial factor leading to the stagnation of both cell growth and ectoine biosynthesis.ConclusionsThis study conducted a comprehensive analysis of H. elongata’s stress response to NaCl shock at multiple scales. It extends the understanding of stress response of halophilic bacteria to NaCl shock and provides promising theoretical insights to guide future improvements in optimizing industrial ectoine production.

Epigenetic control on transcription of vernalization genes and whole-genome gene expression profile induced by vernalization in common wheat

Vernalization is necessary for winter wheat to flower. However, it is unclear whether vernalization is also required for spring wheat, which is frequently sown in fall, and what molecular mechanisms underlie the vernalization response in wheat varieties. In this study, we examined the molecular mechanisms that regulate vernalization response in winter and spring wheat varieties. For this purpose, we determined how major vernalization genes (VRN1, VRN2, and VRN3) respond to vernalization in these varieties and whether modifications to histones play a role in changes in gene expression. We also identified genes that are differentially regulated in response to vernalization in winter and spring wheat varieties. We found that in winter wheat, but not in spring wheat, VRN1 expression decreases when returned to warm temperature following vernalization. This finding may be associated with differences between spring and winter wheat in the levels of tri-methylation of lysine 27 on histone H3 (H3K27me3) and tri-methylation of lysine 4 on histone H3 (H3K4me3) at the VRN1 gene. Analysis of winter wheat transcriptomes before and after vernalization revealed that vernalization influences the expression of several genes, including those involved in leucine catabolism, cysteine biosynthesis, and flavonoid biosynthesis. These findings provide new candidates for further study on the mechanism of vernalization regulation in wheat.

Genomic Data Reveal Diverse Biological Characteristics of Scleractinian Corals and Promote Effective Coral Reef Conservation.

Reef-building corals (Scleractinia, Anthozoa, Cnidaria) are the keystone organisms of coral reefs, which constitute the most diverse marine ecosystems. Since the first decoded coral genome reported in 2011, about 40 reference genomes are registered as of 2023. Comparative genomic analyses of coral genomes have revealed genomic characters that may underlie unique biological characteristics and coral diversification. These include existence of genes for biosynthesis of mycosporine-like amino acids, loss of an enzyme necessary for cysteine biosynthesis in family Acroporidae, and lineage-specific gene expansions of DMSP lyase-like genes in the genus Acropora. While symbiosis with endosymbiotic photosynthetic dinoflagellates is a common biological feature among reef-building corals, genes associated with the intricate symbiotic relationship encompass not only those shared by many coral species, but also genes that were uniquely duplicated in each coral lineage, suggesting diversified molecular mechanisms of coral-algal symbiosis. Coral genomic data have also enabled detection of hidden, complex population structures of corals, indicating the need for species-specific, local-scale, carefully considered conservation policies for effective maintenance of corals. Consequently, accumulating coral genomic data from a wide range of taxa and from individuals of a species not only promotes deeper understanding of coral reef biodiversity, but also promotes appropriate and effective coral reef conservation. Considering the diverse biological traits of different coral species and accurately understanding population structure and genetic diversity revealed by coral genomic analyses during coral reef restoration planning could enable us to "archive" coral reef environments that are nearly identical to natural coral reefs.

Auxotrophy of <I>Yersinia pestis</I> Strains of Antiqua Biovar and Its Genetic Basis

The aim of the work was to study the growth dependence on amino acids in Yersinia pestis strains of different phylogenetic branches of the antiqua biovar and to determine the genetic basis of auxotrophy of these strains.Materials and methods. We used 38 strains of Y. pestis, the main subspecies of the antiqua biovar, isolated in various foci of the world in the period of 1928–2020. The nutritional requirements of the strains were determined by incubation on Difco minimal agar with different sets of amino acids. Phylogenetic analysis of the strains was carried out using the Wombac 2.0 and SeaView 5.0.5 programs. Comparative analysis of the nucleotide sequences of the genes was performed using the BLAST algorithm and the Mega 7.0 program.Results and discussion. The phylogenetic appurtenance of the investigated Y. pestis strains of antiqua biovar to the phylogenetic branches 0.ANT3, 0.ANT5, 1.ANT, 2.ANT3, 3.ANT2, 4.ANT has been determined. It is established that all studied strains have a common dependence of growth on three amino acids – phenylalanine, threonine, and methionine. In the majority of the strains of antiqua biovar of all phylogenetic branches, growth is also dependent on the presence of cysteine in the medium, except for a part of the strains of the phylogenetic branch 4.ANT. In 14 genes of sulfur and cysteine metabolism, 19 mutations have been identified. Each phylogenetic group of the antique biovar has a distinct profile of mutations in genes involved in cysteine biosynthesis. The leucine requirement of the strains belonging to phylogenetic branch 0.ANT5 has been established, possibly caused by a frame shift in the leuA gene. Strains of the 1.ANT branch isolated in the Democratic Republic of the Congo demonstrate an additional proline-dependent growth. The defined nutritional requirements in the strains and the genetic causes of auxotrophy complement the phenotypic and genetic characteristics of the phylogenetic branches of the antiqua biovar and can be used as genetic markers for the differentiation of these strains.