Synthesis Of Γ-aminobutyric Acid Research Articles

Non-Targeted Metabolomics Analysis of γ-Aminobutyric Acid Enrichment in Germinated Maize Induced by Pulsed Light.

Pulsed light is an emerging technique in plant physiology recognized for its ability to enhance germination and accumulate γ-aminobutyric acid in maize. Pulsed light involves exposing plants to brief, high-intensity bursts of light, which can enhance photosynthesis, improve growth, and increase resistance to environmental stresses. Despite its promising potential, the specific metabolic changes leading to γ-aminobutyric acid enrichment in maize induced by pulsed light are not fully understood. This study addresses this gap by quantifying key nutrients and γ-aminobutyric acid-related compounds during maize germination and investigating the underlying mechanisms using non-targeted metabolomics. Our findings indicate that pulsed light significantly promotes maize germination and accelerates the hydrolysis of proteins, sugars, and lipids. This acceleration is likely due to the activation of enzymes involved in these metabolic pathways. Additionally, pulsed light markedly increases the content of glutamic acid and the activity of glutamate decarboxylase, which are crucial for γ-aminobutyric acid synthesis. Moreover, pulsed light significantly reduces the activity of γ-aminobutyric transaminase, thereby inhibiting γ-aminobutyric acid decomposition and resulting in a substantial increase in γ-aminobutyric acid content, with a 27.20% increase observed in germinated maize following pulsed light treatment. Metabolomic analysis further revealed enrichment of metabolic pathways associated with γ-aminobutyric acid, including amino acid metabolism, carbohydrate metabolism, plant hormone signal transduction, energy metabolism, pyrimidine metabolism, and ABC transporters. In conclusion, pulsed light is a robust and efficient method for producing sprouted maize with a high γ-aminobutyric acid content. This technique provides a novel approach for developing sprouted cereal foods with enhanced nutritional profiles, leveraging the physiological benefits of γ-aminobutyric acid, which include stress alleviation and potential health benefits for humans.

Whole genome sequence analysis and in vitro probiotic characteristics of Lactococcus lactis ZFM559

Lactococcus lactis, a candidate probiotic, is extensively applied in the fermentation of the food industry and is recognized for its potential to enhance human health. In this study, L. lactis ZFM559, which exhibits probiotic properties, was isolated from fresh milk. In vitro assays have demonstrated it has the ability to inhibit and co-aggregate with multiple pathogenic strains, as well as good tolerance to high osmotic pressure (10% NaCl), low pH (3.0), and simulated gastrointestinal conditions. Moreover, L. lactis ZFM559 is capable of producing folate and inhibiting α-glucosidase activity. Whole-genome sequencing has revealed the components of its genome, which include one circular chromosome and three linear plasmids. Functional annotation of the genome has identified the pathway for γ-aminobutyric acid synthesis, genes and enzymes associated with flavor production and lactose decomposition, and proteins related to environmental stress tolerance. Additionally, a complete gene cluster (including LanT, HlyD, LcnB, and GlyS) for the synthesis of bacteriocins was identified. In summary, L. lactis ZFM559 can be considered a probiotic with significant potential for applications in the food industry and human health.

MdSINA2-MdNAC104 Module Regulates Apple Alkaline Resistance by Affecting γ-Aminobutyric Acid Synthesis and Transport.

Soil alkalization is an adverse factor limiting plant growth and yield. As a signaling molecule and secondary metabolite, γ-aminobutyric acid (GABA) responds rapidly to alkaline stress and enhances the alkaline resistance of plants. However, the molecular mechanisms by which the GABA pathway adapts to alkaline stress remain unclear. In this study, a transcription factor, MdNAC104 is identified, from the transcriptome of the alkaline-stressed roots of apple, which effectively reduces GABA levels and negatively regulates alkaline resistance. Nevertheless, applying exogenous GABA compensates the negative regulatory mechanism of overexpressed MdNAC104 on alkaline resistance. Further research confirms that MdNAC104 repressed the GABA biosynthetic gene MdGAD1/3 and the GABA transporter gene MdALMT13 by binding to their promoters. Here, MdGAD1/3 actively regulates alkaline resistance by increasing GABA synthesis, while MdALMT13 promotes GABA accumulation and efflux in roots, resulting in an improved resistance to alkaline stress. This subsequent assays reveal that MdSINA2 interacts with MdNAC104 and positively regulates root GABA content and alkaline resistance by ubiquitinating and degrading MdNAC104 via the 26S proteasome pathway. Thus, the study reveals the regulation of alkaline resistance and GABA homeostasis via the MdSINA2-MdNAC104-MdGAD1/3/MdALMT13 module in apple. These findings provide novel insight into the molecular mechanisms of alkaline resistance in plants.

Case for supporting astrocyte energetics in glucose transporter 1 deficiency syndrome.

In glucose transporter 1 deficiency syndrome (Glut1DS), glucose transport into brain is reduced due to impaired Glut1 function in endothelial cells at the blood-brain barrier. This can lead to shortages of glucose in brain and is thought to contribute to seizures. Ketogenic diets are the first-line treatment and, among many beneficial effects, provide auxiliary fuel in the form of ketone bodies that are largely metabolized by neurons. However, Glut1 is also the main glucose transporter in astrocytes. Here, we review data indicating that glucose shortage may also impact astrocytes in addition to neurons and discuss the expected negative biochemical consequences of compromised astrocytic glucose transport for neurons. Based on these effects, auxiliary fuels are needed for both cell types and adding medium chain triglycerides (MCTs) to ketogenic diets is a biochemically superior treatment for Glut1DS compared to classical ketogenic diets. MCTs provide medium chain fatty acids (MCFAs), which are largely metabolized by astrocytes and not neurons. MCFAs supply energy and contribute carbons for glutamine and γ-aminobutyric acid synthesis, and decanoic acid can also block α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid glutamate receptors. MCTs do not compete with metabolism of ketone bodies mostly occurring in neurons. Triheptanoin, an anaplerotic but also gluconeogenic uneven MCT, may be another potential addition to ketogenic diets, although maintenance of "ketosis" can be difficult. Gene therapy has also targeted both endothelial cells and astrocytes. Other approaches to increase fuel delivery to the brain currently investigated include exchange of Glut1DS erythrocytes with healthy cells, infusion of lactate, and pharmacological improvement of glucose transport. In conclusion, although it remains difficult to assess impaired astrocytic energy metabolism invivo, astrocytic energy needs are most likely not met by ketogenic diets in Glut1DS. Thus, we propose prospective studies including monitoring of blood MCFA levels to find optimal doses for add-on MCT to ketogenic diets and assessing of short- and long-term outcomes.

Using deep eutectic solvents to enhance immobilized glutamate decarboxylase for γ-aminobutyric acid synthesis

Deep eutectic solvents (DESs) can improve the catalytic efficiency of enzymes. The effect of DESs on the biocatalytic decarboxylation of sodium glutamate to γ-aminobutyric acid (GABA) by site-directed immobilized enzymes was studied. 1.5% choline chloride/glycerol (ChCl/Gly, molar ratio, 2:1) increased the catalytic rate of the site-directed immobilized enzyme by 14%. In ChCl/Gly-containing systems, the Km, kcat, activity and activation energy of the enzyme were 3.17 mM, 48.86 s−1, 48.41 U/mg and 28.69 kJ/mol, respectively. Furthermore, ChCl/Gly resulted in the change of the secondary structure of the immobilized enzyme. The optimum pH and temperature of the enzymatic reaction were 3.0 and 60 °C in ChCl/Gly-containing systems, respectively. Finally, GABA was afforded in a yield of 78.3% at a substrate concentration of up to 180 mM using a fed-batch strategy. This study provides a green and promising method for efficient GABA biosynthesis.

Effects of different soaking and germinating conditions on γ-aminobutyric acid, antioxidant activity, and chemical composition of djulis (Chenopodium formosanum)

Djulis (Chenopodium formosanum), a native plant of Taiwan, is esteemed for its rich nutritional profile, encompassing high levels of dietary fiber, proteins, essential amino acids, and microelements. This study delved into the influence of soaking and germinating conditions on the synthesis of γ-aminobutyric acid (GABA), total phenolic content (TPC), antioxidant activity, and enzymatic activity in djulis. Enrichment culture tests were conducted to ascertain optimal soaking conditions. Results revealed that soaking djulis seeds for 4 h at 25 °C before germination notably augmented GABA production. Furthermore, djulis seeds subjected to soaking and germination at 30 °C for 48 h exhibited heightened GABA and anthocyanin contents. Conversely, germination at 25 °C for 48 h demonstrated superior TPC and 2,2-diphenylpicrylhydrazyl (DPPH) free radical scavenging activity. Optimal concentrations of glutamic acid, monosodium glutamate, pyridoxal-5′-phosphate (vitamin B6), Ca2+, and pH were found to enhance glutamine acid decarboxylase activity, consequently elevating GABA content. In summary, fine-tuning soaking and germinating conditions presents a promising avenue for augmenting GABA production in djulis, thereby bolstering its nutritional and functional utility. Future investigations aimed at elucidating the molecular mechanisms underlying enzymatic activity modulation during soaking and germination could yield valuable insights into optimizing GABA production.

Stiff-Person Syndrome

Stiff-person syndrome (SPS) is a rare autoimmune neurological disorder characterized by progressive axial muscle stiffness, central nervous system hyper-excitability, and painful stimulus-sensitive muscle spasms. SPS is classified into classic SPS and SPS variants, including stiff-limb syndrome (SLS) and progressive encephalomyelitis with rigidity and myoclonus (PERM), based on clinical presentation. SPS responds to immunotherapy, and several autoantigens have been identified. Most patients with SPS have high-titers of antibodies against glutamic acid decarboxylase (GAD), the rate-limiting enzyme for the synthesis of γ-aminobutyric acid (GABA), and up to 15% of the patients have antibodies against the glycine receptor α-subunit.

Analytical evaluation of a GAD65 antibodies chemiluminescence immunoassay for CSF in neurological syndromes.

Antibodies against glutamic acid decarboxylase isoform 65 (GAD-Ab) have been found in different severe neurological conditions associated with altered synthesis of γ-aminobutyric acid (GABA). Serum GAD-Ab can be found in up to 90 % of patients with type 1 diabetes mellitus (T1DM), mostly at relatively low concentrations, while high concentrations of GAD-ab are thought to be more frequently associate to a neurological condition, with levels 100-folds higher than those found in T1DM. Although CSF testing is recommended when suspecting a GAD-associated neurological syndrome, no commercial immunoassay is validated for this use and no cut-off is internationally recognized to support the diagnosis. In this study we validated CSF testing of GAD-Ab on an automated chemiluminescence (CLIA) immunoassay that had previously shown good agreement with ELISA on serum. We tested 43 CSF from patients with typical GAD-associated neurological disorders and patients with other neurological conditions, identifying a clinical cut-off of 18 kIU/L that discriminated GAD-disease with an area under the curve (AUC) of 0.921. CLIA showed good analytical performances on repeatability and recovery tests in CSF and confirmed an excellent agreement with ELISA. GAD-Ab associated neurological disorders are rare but CSF testing for GAD-Ab is a common request for neurologists when suspecting an insidious autoimmune central nervous system disease. CLIA platforms are expected to be increasingly adopted in clinical laboratories due to their flexibility and reliability, therefore studies on decisional levels should be implemented for improving the interpretation and utilization of laboratory data.

Neuronal Calcium Sensor-1 Protects Cortical Neurons from Hyperexcitation and Ca2+ Overload during Ischemia by Protecting the Population of GABAergic Neurons.

A defection of blood circulation in the brain leads to ischemia, damage, and the death of nerve cells. It is known that individual populations of GABAergic neurons are the least resistant to the damaging factors of ischemia and therefore they die first of all, which leads to impaired inhibition in neuronal networks. To date, the neuroprotective properties of a number of calcium-binding proteins (calbindin, calretinin, and parvalbumin), which are markers of GABAergic neurons, are known. Neuronal calcium sensor-1 (NCS-1) is a signaling protein that is expressed in all types of neurons and is involved in the regulation of neurotransmission. The role of NCS-1 in the protection of neurons and especially their individual populations from ischemia and hyperexcitation has not been practically studied. In this work, using the methods of fluorescence microscopy, vitality tests, immunocytochemistry, and PCR analysis, the molecular mechanisms of the protective action of NCS-1 in ischemia/reoxygenation and hyperammonemia were established. Since NCS-1 is most expressed in GABAergic neurons, the knockdown of this protein with siRNA led to the most pronounced consequences in GABAergic neurons. The knockdown of NCS-1 (NCS-1-KD) suppressed the basic expression of protective proteins without significantly reducing cell viability. However, ischemia-like conditions (oxygen-glucose deprivation, OGD) and subsequent 24-h reoxygenation led to a more massive activation of apoptosis and necrosis in neurons with NCS-1-KD, compared to control cells. The mass death of NCS-1-KD cells during OGD and hyperammonemia has been associated with the induction of a more pronounced network hyperexcitation symptom, especially in the population of GABAergic neurons, leading to a global increase in cytosolic calcium ([Ca2+]i). The symptom of hyperexcitation of neurons with NCS-1-KD correlated with a decrease in the level of expression of the calcium-binding protein-parvalbumin. This was accompanied by an increase in the expression of excitatory ionotropic glutamate receptors, N-methyl-D-aspartate and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (NMDAR and AMPAR) against the background of suppression of the expression of glutamate decarboxylase (synthesis of γ-aminobutyric acid).

Association of Serum Pyridoxal Phosphate Levels with Established Status Epilepticus.

The objective of this study was to determine the prevalence of pyridoxine deficiency, measured by pyridoxal phosphate (PLP) levels, in patients admitted to the hospital with established (benzodiazepine-resistant) status epilepticus (SE) (eSE) and to compare to three control groups: intensive care unit (ICU) patients without SE (ICU-noSE), non-ICU inpatients without SE (non-ICU), and outpatients with or without a history of epilepsy (outpatient). This retrospective cohort study was conducted at the University of North Carolina Hospitals and Yale New Haven Hospital. Participants included inpatients and outpatients who had serum PLP levels measured during clinical care between January 2018 and March 2021. The first PLP level obtained was categorized as normal (> 30nmol/L), marginal (≤ 30nmol/L), deficient (≤ 20nmol/L), and severely deficient (≤ 5nmol/L). A total of 293 patients were included (52 eSE, 40 ICU-noSE, 44 non-ICU, and 157 outpatient). The median age was 55 (range 19-99) years. The median PLP level of the eSE group (12nmol/L) was lower than that of the ICU-noSE (22nmol/L, p = 0.003), non-ICU (16nmol/L, p = 0.05), and outpatient groups (36nmol/L, p < 0.001). Patients with eSE had a significantly higher prevalence of marginal and deficient PLP levels (90 and 80%, respectively) than patients in each of the other three groups (ICU-noSE: 70, 50%; non-ICU: 63, 54%; outpatient: 38, 21%). This significantly higher prevalence persisted after correcting for critical illness severity and timing of PLP level collection. Our study confirms previous findings indicating a high prevalence of pyridoxine deficiency (as measured by serum PLP levels) in patients with eSE, including when using a more restricted definition of pyridoxine deficiency. Prevalence is higher in patients with eSE than in patients in all three control groups (ICU-noSE, non-ICU, and outpatient). Considering the role of pyridoxine, thus PLP, in the synthesis of γ-aminobutyric acid and its easy and safe administration, prospective studies on pyridoxine supplementation in patients with eSE are needed.

Stimulation of antioxidant activity and γ-aminobutyric acid synthesis in germinated wheat grain Triticum aestivum L. by ultrasound: Increasing the nutritional value of the product

The use of ultrasound to intensify the germination process of Triticum aestivum L. wheat was studied. This method of controlled germination can be used in several sectors of food industry, in particular in bakery. The effect of low-frequency ultrasound (20 kHz) at different intensities and duration on the germination process of Triticum aestivum L. wheat was systematically studied. We have found that 3-minute processing at 227 W/l output reduces the duration of wheat grain germination by 25% (12 ± 2 h) compared to the control samples. The use of ultrasound stimulated γ-aminobutyric acid (GABA) synthesis (18.9 ± 0.5 mg/100 g), increased the antioxidant activity (AOA) (2.86 ± 0.2 mg/g Trolox equivalents) and the amount of flavonoids (0.19 ± 0.03 mg QE/g). The SEM analysis of powder particles of whole-wheat flour made from wheat germinated with ultrasound exposure showed densely packed aggregates of protein matrix. To sum up, controlled ultrasound during wheat grain germination increases the amount of GABA and AOA. The whole-wheat flour is useful for food enrichment.

Determination of Antiviral Mechanism of Centenarian Gut-Derived Limosilactobacillus fermentum Against Norovirus.

Although noroviruses are the causative agents of most non-bacterial foodborne disease outbreaks, effective antivirals are currently unavailable. Certain probiotic strains have been reported as active antivirals for norovirus infections, but their mechanisms have not been fully elucidated. Herein, we examined the antiviral potential of 122 lactic acid bacteria isolates against murine norovirus (MNV), a human norovirus surrogate. A centenarian gut-derived strain, Limosilactobacillus fermentum PV22, exhibited the strongest MNV antagonism and reduced the viral titer by 2.23 ± 0.38 (log-value) in 5 min with stable activity at 25°C (P < 0.01). Genome mining revealed that its antiviral activity can be attributed to the synthesis of γ-aminobutyric acid, and this finding was experimentally verified. Furthermore, we demonstrated the safety of the isolate and its high intestinal colonization ability. In conclusion, we discovered a centenarian gut-derived L. fermentum strain with strong anti-norovirus activity and identified its antiviral metabolite. Our results will offer new solutions for the prevention and treatment of food-related norovirus infections.

Comparative study on the influence of silicon and selenium to mitigate arsenic induced stress by modulating TCA cycle, GABA, and polyamine synthesis in rice seedlings.

Arsenic contamination of groundwater is a major concern for its usage in crop irrigation in many regions of the world. Arsenic is absorbed by rice plants mainly from arsenic contaminated water during irrigation. It hampers growth and agricultural productivity. The aim of the study was to mitigate the toxic effects of arsenate (As-V) [25 μM, 50 μM, and 75 μM] by silicon (Si) [2 mM] and selenium (Se) [5 μM] amendments on the activity of the TCA cycle, synthesis of γ-aminobutyric acid (GABA) and polyamines (PAs) in rice (Oryza sativa L. cv. MTU-1010) seedlings and to identify which chemical was more potential to combat this threat. As(V) application decreased the activities of tested respiratory enzymes and increased the levels of organic acids (OAs) in the test seedlings. Application of Si with As(V) and Se with As(V) increased the activities of respiratory enzymes and the levels of OAs. The effects were more pronounced during Si amendments. The activities of GABA synthesizing enzymes along with accumulation of GABA were increased under As(V) stress. During joint application of Si with As(V) and Se with As(V) the activity and the level of said parameters were decreased that indicating defensive role of these chemicals to resist As(V) toxicity in rice and Si amendments showed greater potential to reduce As(V) induced damages in the test seedlings. PAs trigger tolerance mechanism against As(V) in plants. PAs such as putrescine, spermidine and spermine were synthesized more during Si and Se amendments in As(V) contaminated rice seedlings to combat the toxic effects of As(V). Si amendments substantially modulated the toxic effects caused by As(V) over Se amendments in the As(V) challenged test seedlings. Thus, in future application of Si enriched fertilizer will be beneficial to grow rice plants with normal vigor in arsenic contaminated soil.

Cancer-cell-derived GABA promotes β-catenin-mediated tumour growth and immunosuppression.

Many cancers have an unusual dependence on glutamine. However, most previous studies have focused on the contribution of glutamine to metabolic building blocks and the energy supply. Here, we report that cancer cells with aberrant expression of glutamate decarboxylase 1 (GAD1) rewire glutamine metabolism for the synthesis of γ-aminobutyric acid (GABA)-a prominent neurotransmitter-in non-nervous tissues. An analysis of clinical samples reveals that increased GABA levels predict poor prognosis. Mechanistically, we identify a cancer-intrinsic pathway through which GABA activates the GABAB receptor to inhibit GSK-3β activity, leading to enhanced β-catenin signalling. This GABA-mediated β-catenin activation both stimulates tumour cell proliferation and suppresses CD8+ T cell intratumoural infiltration, such that targeting GAD1 or GABABR in mouse models overcomes resistance to anti-PD-1 immune checkpoint blockade therapy. Our findings uncover a signalling role for tumour-derived GABA beyond its classic function as a neurotransmitter that can be targeted pharmacologically to reverse immunosuppression.

Stimulation of Antioxidant Activity and γ-Aminobutyric Acid Synthesis in Germinated Wheat Grain &lt;i&gt;Triticum Aestivum L.&lt;/i&gt; By Ultrasound: Increasing the Nutritional Value of the Product

Stimulation of Antioxidant Activity and γ-Aminobutyric Acid Synthesis in Germinated Wheat Grain &lt;i&gt;Triticum Aestivum L.&lt;/i&gt; By Ultrasound: Increasing the Nutritional Value of the Product

Front Cover: Design of a Full‐Consensus Glutamate Decarboxylase and Its Application to GABA Biosynthesis (ChemBioChem 8/2022)

Glutamate decarboxylase (GAD) is a remarkable biocatalyst for the synthesis of γ-amino butyric acid (GABA) from l-glutamate. In this study, artificial GAD named FcGAD (full consensus glutamate decarboxylase) was designed by consensus protein design. FcGAD exhibits suitable properties for application in GABA biosynthesis. This Front Cover (created by Takashi Tsujino, Science Graphics. Co., Ltd.) highlights the design concept and application of FcGAD to the biosynthesis. More information can be found in the Full Paper by S. Nakano, S. Ito et al.

Indigenous Proline is a Two-Dimensional Safety-Relief Valve in Balancing Specific Amino Acids in Rice under Hexavalent Chromium Stress.

This study highlights the roles of different N sources (N starvation [-N], nitrate [+NO3-], and ammonium [+NH4+]) in specific amino acids involved in rice proline (Pro) metabolism under hexavalent chromium [Cr(VI)] stress. In treatment with Cr(VI) - N, the content of glutamate (Glu) in shoots was comparable to that of Pro, while the content of Glu in the roots was significantly higher than that of Pro. In case of treatment with Cr(VI) + NO3-/NH4+, the content of Glu in both tissues was significantly higher than that of Pro, suggesting that the synthesis of γ-aminobutyric acid and glutathione was most likely involved. Pro synthesis in rice is mainly derived from the Glu pathway rather than the ornithine (Orn) pathway, which is strongly affected by different N sources. The genetic regulation network of Pro metabolism demonstrated a good signal for describing amino acid balance in rice under Cr(VI) stress.

169-LB: Type 1 Diabetes Mellitus and Stiff-Person Syndrome

Introduction: Type 1 diabetes mellitus (T1DM) is often associated with other autoimmune diseases. One of them is Stiff-Person Syndrome (SPS), a rare neurological disorder characterized by muscle spasms and progressive muscle stiffness, which most often affects females. Glutamic acid decarboxylase antibodies (anti-GAD) are associated with the pathogenesis of this disease as well as T1DM. These antibodies cause a deficit in the synthesis of γ-aminobutyric acid (GABA) that is essential both in the function as neurotransmitter and in the secretion of insulin in pancreatic β cells. Clinical case: We present the case of a 32-year-old female patient diagnosed with T1DM at 18 years old. Currently under intensive functional insulin therapy and flash glucose monitoring (FGM). Since 2019 with subcutaneous insulin infusion system. At the age of 26, the patient reports dystonia in the left lower limb with subsequent involvement of the contralateral lower limb, upper limbs, trunk and face. Collaboration was made with the Neurology department. Among the laboratory findings, of note: positive serum anti-GAD65 (5437 U/mL; &amp;lt;1) and positive cerebrospinal fluid anti-GAD65 (126.23 U /mL; &amp;lt;1). The diagnosis of SPS was made. The patient started human immunoglobulin therapy with progressive clinical improvement. Estimated HbA1c from FGM was 6,8 % at February, 2021. Discussion: The association between T1DM and SPS is frequent. In this case, a patient with a known history of T1DM was presented, but cases of diagnosis of T1DM in patients with SPS have also been described. About 43% of patients have T1DM at the time of diagnosis of SPS. Anti-GAD are involved in the pathophysiology of these two diseases and anti-GAD titers are much higher in cases of association with SPS (about 50 to 100 times). In the treatment of patients with T1DM, physicians should be alert to the onset of other autoimmune diseases and active surveillance is essential for early diagnosis. Disclosure C. A. Araújo: None. C. Baptista: None. I. Paiva: None. A. Morgadinho: None.

Stiff-Person Syndrome

Stiff-person syndrome (SPS) is a neurological disorder characterized by fluctuating muscle rigidity and painful spasms that occur spontaneously or are triggered by diverse stimuli. Partial or segmental forms of the disorder, such as stiff-limb syndrome (SLS) and the more severe disease called progressive encephalomyelitis with rigidity and myoclonus (PERM), are usually considered within the spectrum of SPS. SPS responds to immunotherapies, and several autoantigens have been identified. Most patients with SPS have high titers of antibodies against glutamic acid decarboxylase (GAD), the enzyme that limits the rate of the synthesis of γ-aminobutyric acid (GABA), and up to 15% have antibodies against the glycine receptor α-subunit.

Effects of NaCl and ethanol stresses on γ-aminobutyric acid synthesis in Kocuria kristinae

Kocuria kristinae, one of the dominant strains in Kedong sufu, can generate γ-aminobutyric acid (GABA). NaCl and ethanol are added to sufu for preservation. This study aims to reveal the effects of NaCl and ethanol stresses on GABA synthesis in K. kristinae. The results suggested that high GABA production was obtained by adding 6% NaCl at the mid-exponential growth phase and 3% ethanol at the late exponential growth phase. Two GABA synthesis pathways were observed, including a new GABA synthesis pathway. Under NaCl stress, genes were upregulated by 1.46- to 3.67-fold in two synthesis pathways of GABA. Under ethanol stress, genes were upregulated by 1.20- to 6.39-fold in two synthesis pathways of GABA, except for speG and MAO. However, their corresponding metabolites were downregulated by 1.02- to 7.69-fold. The changes in genes and metabolites in the carbohydrate and amino acid metabolism pathways and in membrane transport suggested that different metabolic strategies were used to cope with NaCl and ethanol stresses in K. kristinae. The molecular mechanism in improving the production of GABA by NaCl and ethanol stresses was shown in K. kristinae. This study provides a theoretical basis for the development of GABA-enriched sufu by NaCl and ethanol stresses.