Optimization of the Zhou Tian Formula extraction technology based on AHP-CRITIC method and analysis of transfer efficiency of key components based on HPLC fingerprinting.

INTRODUCTION: Zhou Tian Formula (ZTF) is an antidepressant traditional Chinese medicine utilized widely in clinical settings for the treatment of patients with depression. However, shortcomings persist in its extraction technology and quality control. OBJECTIVE: This study aimed to propose a methodology for ZTF extraction technology based on the analytic hierarchy process (AHP)-criteria importance through intercriteria correlation (CRITIC) method and to establish a quality control framework for the efficient transfer of index components. METHOD: Firstly, we analyzed the chemical components of ZTF and determined the optimal extraction technology. Secondly, we calculated the transfer efficiency of the index components during the conversion of water decoction to extract powder and subsequently to granules. Thirdly, we established HPLC fingerprints for 15 batches of ZTF water decoction, extract powder, and granules. We employed SIMCA software to analyze the chemicals responsible for variations in quality among different batches of ZTF granules. RESULTS: We determined the optimal extraction process. The average transfer efficiency of ferulic acid, puerarin, mirificin, isoferulic acid, and calycosin during the conversion of water decoction to extract powder and subsequently to granules exceeded 41%. The HPLC fingerprints of ZTF exhibited a similarity exceeding 0.890. Variable importance in projection values indicated that calycosin, ferulic acid, and puerarin were the primary contributors to quality variations. CONCLUSIONS: The AHP-CRITIC method, coupled with an orthogonal array design, could be used for exploring extraction technology. In addition, the rules governing the transfer of index components from water decoction to extract powder, and subsequently to granules, could be applied for the evaluation and quality assessment of ZTF.

Occurrence of liquid crystal monomers in indoor and outdoor air particle matters (PM10): Implications for human exposure indoors.

Liquid crystal monomers (LCMs) are potentially persistent, bioaccumulating, and toxic substances. However, limited data are available on the occurrence of LCMs in indoor and outdoor air particle matter (PM10) in residential areas. Herein, residential areas near an e-waste dismantling center (Guiyu Town, Shantou City), as well as areas away from the e-waste site (Jiedong District, Jieyang City) were selected as the sampling areas. PM10 was collected from the indoor environments of Guiyu (IGY) and Jieyang (IJY), as well as those from the outdoor environments (OGY and OJY) using the high-volume air samplers (TH-10000C). The levels of 57 LCMs in PM10 were analyzed, and the highest concentrations of LCMs were found in IGY (0.970-1080 pg/m3), followed by IJY (2.853-455 pg/m3), OGY (0.544-116 pg/m3) and OJY (0.258-35.8 pg/m3). No significant difference was observed for LCM levels in indoor PM10 between the two areas (p > 0.05), which were significantly higher than those in outdoors (p < 0.05), indicating that the release of electronic products in general indoor environments is a source of LCMs that cannot be ignored. The compositions of LCMs in outdoors were not consistent with those of indoors. The correlation analysis of individual LCMs suggested potential different sources to the LCMs in indoor and outdoor environments. The median daily intake values of Σ46LCMs via inhalation were estimated as 0.440, 1.46 × 10-2, 0.170 and 1.19 × 10-2 ng/kg BW/day for adults, and as 2.27, 2.60 × 10-2, 0.880 and 2.10 × 10-2 ng/kg BW/day for toddlers, respectively, indicating much higher exposure doses of LCMs indoors compared with the outdoors, and much higher doses for toddlers compared with adults (p < 0.05). These results reveal the potentially adverse effects of LCMs on vulnerable populations, such as toddlers, in indoor environments.

Food-grade γ-aminobutyric acid production by immobilized glutamate decarboxylase from Lactobacillus plantarum in rice vinegar and monosodium glutamate system.

OBJECTIVES: γ-amino butyric acid (GABA) is a non-protein amino acid, considered a potent bioactive compound. This study focused on biosynthesis of food-grade GABA by immobilized glutamate decarboxylase (GAD) from Lactobacillus plantarum in the rice vinegar and monosodium glutamate (MSG) reaction system. RESULTS: The gene encoding glutamate decarboxylase (GadB) from L. plantarum has been heterologously expressed in Lactococcus lactis and biochemically characterized. Recombinant GadB existed as a homodimer, and displayed maximal activity at 40 °C and pH 5.0. The Km value and catalytic efficiency (kcat/Km) of GadB for L-Glu was 22.33 mM and 62.4 mM-1 min-1, respectively, with a specific activity of 24.97 U/mg protein. Then, purified GadB was encapsulated in gellan gum beads. Compared to the free enzyme, immobilized GadB showed higher operational and storage stability. Finally, 9.82 to 21.48 g/L of GABA have been acquired by regulating the amounts of catalyst microspheres ranging from 0.5 to 0.8 g (wet weight) in 0.8 mL of the designed rice vinegar and MSG reaction system. CONCLUSIONS: The method of production GABA by immobilized GadB microspheres mixed in the rice vinegar and MSG reaction system is introduced herein for the first time. Especially, the results obtained here meet the increased interest in the harnessing of biocatalyst to synthesize food-grade GABA.

Identification of chemical constituents in ethyl acetate soluble extract of Sinopodophylli Fructus based on HPLC-MS~n / 中国中药杂志

A high performance liquid chromatography with a diode array detector combined with electrospray ionization ion trap time-of-flight multistage mass spectrometry(HPLC-DAD-ESI-IT-TOF-MS~n, HPLC-MS~n) method was established for qualitative analysis of the chemical components of ethyl acetate extract from Sinopodophylli Fructus. The analysis was performed on a Kromasil 100-5 C_(18)(4.6 mm×250 mm, 5 μm) column, with a mobile phase consisted of 0.1% formic acid(A) and acetonitrile(B) for gradient at a flow rate of 1.0 mL·min~(-1). Electrospray ionization ion trap time-of-flight multistage mass spectrometry was applied for qualitative analysis under positive and negative ion modes. With use of reference substance, characteristic fragmentation and their HR-MS data, 102 components were identified, including 67 flavonoids and 35 lignans. Among them, 45 compounds were reported in Sinopodophylli Fructus for the first time and 19 compounds were identified as new compounds. PharmMapper was used to predict the bioactivity of compounds that were first reported in Sinopodophylli Fructus, and 20 compounds of them were identified to have potential anticancer activity. The results showed that there were many isomers in the ethyl acetate extract of Folium Nelumbinis, and a total of 19 groups of isomers were found. Among them, C_(21)H_(20)O_8 had the highest number of isomers(18 compounds), all of which were α-peltatin or its isomers; C_(21)H_(20)O_7 ranked second, with 10 compounds, all of which were 8-prenylquercetin-3-methyl ether or its isomers. In conclusion, an HPLC-MS~n method was established for qualitative analysis of the ethyl acetate extract(with anti-breast cancer activity) from Sinopodophylli Fructus in this study, which will provide the evidence for clarifying pharmacological active ingredients of the ethyl acetate extract from Sinopodophylli Fructus against breast cancer.

Simultaneous Quantification of Five Constituents in Asarum insigne Using Ultra-Fast Liquid Chromatography with Tandem Mass Spectrometry / 中国药学杂志

OBJECTIVE: To evaluate the effectiveness and safety of Asarum insigne Diels and develop a sensitive, accurate, and efficient ultra-fast liquid chromatography coupled with triple quadrupole mass spectrometer (UFLC-MS/MS) method for simultaneous quantification of five compounds. METHODS: Chromatographic separation was performed on a Shimadzu shim-pack XR-ODS III column(2.0 mm×75 mm,1.6 μm). The mobile phase was composed of 0.1% aqueous formic acid and methanol and the flow rate was 0.2 mL•min-1. Using the established method, all components could be easily separated within 14 min. All components were detected in multiple reaction monitor mode after positive atmospheric pressure chemical ionization. RESULTS: The method was validated, and had good precision, linearity, lower limit of detection, lower limit of quantification, recovery, and stability. This method was used to determine and compare the contents of five components in different medicinal parts of 11 samples, and the contents of 3,4,5-trimethoxytoluene, 3,5-dimethoxytoluene, methyleugenol in different medicinal parts of Asarum insigne were reported for the first time, which (in ng•mg-1) were as follows: 3,4,5-trimethoxytoluene: 1.5-16.71; 3,5-dimethoxytoluene: 28.59-177.20; methyleugenol: 2.46-22.48; AL-I: 46.39-324.04; 7-OCH3-AL-IV: 12.95-251.04. The content of 7-OCH3-AL-IV and total contents of two aristololactams in roots were lower than those in leaves or flower parts, and the contents of AL-I in flowers (171.9-324.0 ng•mg-1) were higher than those in roots (78.44-124.56 ng•mg-1). For methyleugenol, the contents in roots were lower than those in the other parts. CONCLUSION: It is recommended to remove the leaves, flowers, and rhizomes when using Asarum insigne and use it with extreme caution. The UFLC-MS/MS method established in this study can provide guidance for the quality evaluation and safe clinical use of traditional Chinese medicine derived from Asarum insigne.

Identification based on HPLC and anti-inflammatory targets as well as related constituents analysis of Asarum heterotropoides var. mandshuricum and A. sieboldii / 中国中药杂志

The present work is to establish an HPLC characteristic chromatograms of Asarum heterotropoides var. mandshuricum(AH) and A. sieboldii(AS), combined with cluster analysis for the identification of the two species, and predict their potential anti-inflammatory related targets by network pharmacological method. Eighty-nine samples(12 batches of AS and 77 batches of AH) were analyzed, and 11 characteristic peaks were identified by reference substances, UV spectrum and LC-MS. Cluster analysis showed that AS and AH were divided into two groups, and the ratio of characteristic peak areas can be used to distinguish them. When the ratio of characteristic peak sarisan to kakuol was greater than 5, it was AS, and when the ratio was less than 2, it was AH. The network pharmacological analysis of 119 constituents of Asari Radix et Rhizoma suggested that the anti-inflammatory effect of Asari Radix et Rhizoma might be related to COX-2, COX-1, iNOS, MAPK14, NR3 C1, PPARG and TNF. Among them, COX-2 is a relatively key target, which interacted with the characteristic constituents, asarinin, sesamin, safrole, methyleugenol and sarisan. The characteristic constituents asarinin and sesamin also interacted with the iNOS and MAPK14. Safrole and sarisan can also interact with iNOS, COX-1 and LAT4 H. Methyleugenol also showed interaction with COX-1 and LAT4 H. Since asarinin and sesamin interacted with three targets, COX-2, iNOS and MAPK14, it implied that they were the main active constituents for the anti-inflammatory activity of Asari Radix et Rhizoma. The COX-2 inhibitory activities of asarinin and sesamin were further studied by molecular docking and bioassay. The HPLC method established was simple, feasible and reliable, with predicted anti-inflammatory targets and anti-inflammatory constituents, which could provide a reference for improving the quality evaluation system of Asari Radix et Rhizoma.

Phosphate regulator PhoP directly and indirectly controls transcription of the erythromycin biosynthesis genes in Saccharopolyspora erythraea.

BACKGROUND: The choice of phosphate/nitrogen source and their concentrations have been shown to have great influences on antibiotic production. However, the underlying mechanisms responsible for this remain poorly understood. RESULTS: We show that nutrient-sensing regulator PhoP (phosphate regulator) binds to and upregulates most of genes (ery cluster genes) involved in erythromycin biosynthesis in Saccharopolyspora erythraea, resulting in increase of erythromycin yield. Furthermore, it was found that PhoP also directly interacted with the promoter region of bldD gene encoding an activator of erythromycin biosynthesis, and induced its transcription. Phosphate limitation and overexpression of phoP increased the transcript levels of ery genes to enhance the erythromycin production. The results are further supported by observation that an over-producing strain of S. erythraea expressed more PhoP than a wild-type strain. On the other hand, nitrogen signal exerts the regulatory effect on the erythromycin biosynthesis through GlnR negatively regulating the transcription of phoP gene. CONCLUSIONS: These findings provide evidence that PhoP mediates the interplay between phosphate/nitrogen metabolism and secondary metabolism by integrating phosphate/nitrogen signals to modulate the erythromycin biosynthesis. Our study reveals a molecular mechanism underlying antibiotic production, and suggests new possibilities for designing metabolic engineering and fermentation optimization strategies for increasing antibiotics yield.

[Comparison of the effect of three nickel-titanium instruments on molar root canal curvature].

PURPOSE: To evaluate the influence of ProTaper, Mtwo, and M3 nickel-titanium instruments on root canal curvature during root canal preparation. METHODS: Forty-five molars with root canal therapy were randomly divided into 3 groups. The root canals were prepared by using ProTaper, Mtwo and M3 nickel-titanium instruments. The qualified rate and change of root canal curvature before and after preparation were compared using SPSS22.0 software package. RESULTS: There was no significant difference between the three groups in the qualification rate after root canal preparation and the effect of different preparatory devices on root canal curvature(P>0.05), but there was significant difference in the change of root canal curvature before and after preparation (P<0.05). CONCLUSIONS: The three kinds of nickel-titanium instruments can effectively form root canal and have no difference in root canal curvature， but the curvature of root canal is changed after preparation. It is important to prevent complications during curved root canal preparation.

[Comparison of clinical efficacy of CAD/CAM all -ceramic inlay and polymerid porcelain inlay in restoration of posterior Class II cavity].

PURPOSE: To compare the clinical efficacy of CAD/CAM all-ceramic inlay and polymerid porcelain inlay in restoring Class II cavity of posterior teeth. METHODS: Ninety-seven patients with 100 posterior teeth of ClassII cavity were recruited in this randomized control trial; Among them, 50 patients were grouped into CAD/CAM all-ceramic inlays and 47 patients were grouped into Ceramage polymerid porcelain inlay. According to the modified USPHS criteria, the incidence of postoperative sensitivity, prosthesis fracture, prosthesis falling off, and edge coloration were evaluated 12 months and 24 months after restoration. Chi-square test and Wilcoxon rank sum test were used for statistical analysis using SPSS 13.0 software package. RESULTS: Restoration in the 2 groups were successful, there was no significant difference at 12 months (P>0.05). Postoperative sensitivity and the incidence of prosthesis falling off in both groups were not significantly different (P>0.05); however, the number of prosthesis fracture of the polymerid porcelain was lower than that of the CAD/CAM all-ceramic inlays (P<0.05). The incidence of edge coloration of CAD/CAM all-ceramic inlays was lower than that of the polymerid porcelain at 24-month follow-up (P<0.05). CONCLUSIONS: Restoration with polymerid porcelain is more likely to have a higher success rate than those with CAD/CAM all-ceramic inlays. Patients undergoing CAD/CAM all-ceramic inlays have a lower incidence of edge coloration, compared with those undergoing polymerid porcelain.

Analysis on volatile components in different parts of Asarum insigne by HS-GC-MS / 中草药

Objective To perform qualitative and quantitative analysis on the volatile components in roots, rhizomes, leaves, and flowers of Asari Radix et Rhizoma derived from Asarum insigne. Methods The volatile components were analyzed by HS-GC-MS, and the relative percentage content of each component was calculated with peak area normalization method. Results There were 58 components separated from four parts of A. insigne, including 27 common components in different parts. The principal constituents was trans-β-farnesene, safrole, and asaricin. Their contents were different in four parts. Especially the contents of safrole in rhizomes, leaves, and flowers were up to 34%, 22%, and 21%; The safrole in rhizomes was over twice higher than that in roots (12%). Because safrole was extremely poisonous, the rhizomes, leaves, and flowers should be used carefully. Conclusion The volatile components in A. insigne can be detected by HS-GC-MS simply and quickly. The research can be helpful for development and quality evaluation of A. insigne.

[Influence of age on the effectiveness of revascularization in immature permanent teeth].

PURPOSE: To evaluate the effect of age on the potential of dental pulp regeneration in young permanent teeth with periapical periodontitis. METHODS: A total of 30 mandibular premolars from 9-18 years old patients with pulp necrosis were divided into 2 groups, group A (younger age group): 9-13 years old, and group B (older age group): 14-18 years old. Revascularization procedures were performed for all patients. Follow-up was done for up to 18 months. Standardized radiographs of cone-beam CT (CBCT) were digitally evaluated for increase in root length and thickness. The data were analyzed by nonparametric two sample rank sum test using SPSS13.0 software package. RESULTS: After 18 months of follow-up, the clinical symptoms of the two groups disappeared. The cure rate of group A was significantly higher than that of group B (P=0.003). Radiographic analysis showed that the root length and root canal wall thickness in group A was significantly greater than those in group B (P<0.05). CONCLUSIONS: Root canal revascularization can be widely used in the treatment of dental pulp necrosis in young permanent teeth. The closer the age is to the eruption time, the higher the potential of dental pulp regeneration, and the more suitable for root canal revascularization.

Comparision and analysis on the blood concentration of common Chinese medicine and Western medicine / 药学学报

To a certain extent, the drug effect is determined by its blood concentration. It is generally accepted that the blood concentrations of constituents of Chinese medicines are very low. There is no sufficient experimental bases and references on its degree and the possibility of taking effect. In this study, 69 papers were collected and analyzed by searching the database of Scifinder, Pubmed, CNKI. The minimum effective blood concentrations of 73 common Western medicines and the maximum blood concentrations of 211 in vivo constituents of 40 Chinese medicines (single herb or compound Chinese medicine) were summarized. It was found that the maximum blood concentrations of the most in vivo constituents of Chinese medicines were much less than the minimum effective blood concentrations of the Western medicines. Specifically, the minimum effective blood concentrations of 17 Western medicines (23% of total) and the maximum blood concentrations of the 143 in vivo constituents of Chinese medicines (68% of total) were less than 100 ng ·mL-1; the minimum effective blood concentrations of 31 Western medicines (42% of total) and the maximum blood concentrations of the 20 in vivo constituents of Chinese medicines (9% of total) were more than 1 000 ng·mL-1. In this paper, a systematic summary and comparison of the blood concentrations in traditional Chinese medicines and Western medicines were conducted, which could provide a new ideas and references for the study of the pharmacodynamical material basis and its mechanism in traditional Chinese medicine.

Fingerprint Analysis of Chemical Constituents of Swertia patens / 中国药学杂志

OBJECTIVE: To study the HPLC fingerprint of Swertia patens, the most commonly used substitute of Swertiae Mileensis Herba recorded in Chinese Pharmacopoeia, compare the major chemical constituents between the two kinds of herbs, and provide scientific evidence for their identification and quality control. METHODS: HPLC fingerprint method was used to analyze 12 batches of S. patens and 5 batches of Swertiae Mileensis Herba. Similarity evaluation method and clustering analysis method were introduced to compare the HPLC chromatograms of them. RESULTS: The repetition, stability, and precision of the fingerprint method were good. A total of 13 common peaks were confirmed. The similarities of the chromatograms of 17 batches of Swertia were greater than 0.94. CONCLUSION: Different batches of S. patens and Swertiae Mileensis Herba have high similarity. It is possible for S. patens to take place of Swertiae Mileensis Herba.

GlnR and PhoP Directly Regulate the Transcription of Genes Encoding Starch-Degrading, Amylolytic Enzymes in Saccharopolyspora erythraea.

Starch-degrading enzymes hydrolyze starch- and starch-derived oligosaccharides to yield glucose. We investigated the transcriptional regulation of genes encoding starch-degrading enzymes in the industrial actinobacterium Saccharopolyspora erythraea We observed that most genes encoding amylolytic enzymes (one α-amylase, one glucoamylase, and four α-glucosidases) were regulated by GlnR and PhoP, which are global regulators of nitrogen and phosphate metabolism, respectively. Electrophoretic mobility shift assays and reverse transcription-PCR (RT-PCR) analyses demonstrated that GlnR and PhoP directly interact with their promoter regions and collaboratively or competitively activate their transcription. Deletion of glnR caused poor growth on starch, maltodextrin, and maltose, whereas overexpression of glnR and phoP increased the total activity of α-glucosidase, resulting in enhanced carbohydrate utilization. Additionally, transcript levels of amylolytic genes and total glucosidase activity were induced in response to nitrogen and phosphate limitation. Furthermore, regulatory effects of GlnR and PhoP on starch-degrading enzymes were conserved in Streptomyces coelicolor A3(2). These results demonstrate that GlnR and PhoP are involved in polysaccharide degradation by mediating the interplay among carbon, nitrogen, and phosphate metabolism in response to cellular nutritional states. Our study reveals a novel regulatory mechanism underlying carbohydrate metabolism, and suggests new possibilities for designing genetic engineering approaches to improve the rate of utilization of starch in actinobacteria.IMPORTANCE The development of efficient strategies for utilization of biomass-derived sugars, such as starch and cellulose, remains a major technical challenge due to the weak activity of associated enzymes. Here, we found that GlnR and PhoP directly regulate the transcription of genes encoding amylolytic enzymes and present insights into the regulatory mechanisms of degradation and utilization of starch in actinobacteria. Two nutrient-sensing regulators may play important roles in creating a direct association between nitrogen/phosphate metabolisms and carbohydrate utilization, as well as modulate the C:N:P balance in response to cellular nutritional states. These findings highlight the interesting possibilities for designing genetic engineering approaches and optimizing the fermentation process to improve the utilization efficiency of sugars in actinobacteria via overexpression of the glnR and phoP genes and nutrient signal stimulation.

Reciprocal Regulation of GlnR and PhoP in Response to Nitrogen and Phosphate Limitations in Saccharopolyspora erythraea.

Nitrogen and phosphate source sensing, uptake, and assimilation are essential for the growth and development of microorganisms. In this study, we demonstrated that SACE_6965 encodes the phosphate regulator PhoP, which controls the transcription of genes involved in phosphate metabolism in the erythromycin-producing Saccharopolyspora erythraea. We found that PhoP and the nitrogen regulator GlnR both regulate the transcription of glnR as well as other nitrogen metabolism-related genes. Interestingly, both GlnR- and PhoP-binding sites were identified in the phoP promoter region. Unlike the nonreciprocal regulation of GlnR and PhoP observed in Streptomyces coelicolor and Streptomyces lividans, GlnR negatively controls the transcription of the phoP gene in S. erythraea. This suggests that GlnR directly affects phosphate metabolism and demonstrates that the cross talk between GlnR and PhoP is reciprocal. Although GlnR and PhoP sites in the glnR and phoP promoter regions are located in close proximity to one another (separated by only 2 to 4 bp), the binding of both regulators to their respective region was independent and noninterfering. These results indicate that two regulators could separately bind to their respective binding sites and control nitrogen and phosphate metabolism in response to environmental changes. The reciprocal cross talk observed between GlnR and PhoP serves as a foundation for understanding the regulation of complex primary and secondary metabolism in antibiotic-producing actinomycetes.

Research on inorganic elements of Asari Radix et Rhizoma from different localities and species / 中国中药杂志

<p><b>OBJECTIVE</b>To explore the character of inorganic elements in Asari Radix et Rhizoma (Xixin).</p><p><b>METHOD</b>The contents of 53 inorganic elements in Xixin samples from different localities and species were determined by ICP-AES and ICP-MS. The statistical data were made using SAS.</p><p><b>RESULT</b>The result demonstrated that Xixin has the high contents of Fe, Cr, Li. It has been observed that the content of Cu and Pb of the samples are much higher than the standard level. The results of hierarchical cluster analysis revealed two groups which correspond with the species of the samples. No correlations between the contents of the inorganic elements and the localities of the samples were found. Some characteristic elements were displayed in some specific areas. The difference of the contents of the 53 inorganic elements between root and rhizome of Xixin was reported for the first time. The primary form of inorganic elements in Xixin has been studied for the first time. The result demonstrated that the extraction rate between different elements varied, with the average extraction rate of (22.25 +/- 24.96)%.</p><p><b>CONCLUSION</b>The inorganic elements analysis of Xixin can provide evidence of its identification, cultivation and application.</p>

[Preparation and identification of polyclonal antibody against small peptides of beta-tubulin of Toxoplasma gondii].

The amino acid sequences of beta-tubulin from Toxoplasma gondii stains (GT1 and ME49) and human were aligned by ClustalW2 software. Based on the alignment result, the C-terminal peptides of beta-tubulin of T. gondii were artificially synthesized. Rabbits were immunized with 0.5 mg synthesized peptides for five times at 2-week intervals. Serum samples were collected at the second week after the final immunization, and were analyzed for specific antibodies by ELISA. Finally, the specific-beta-tubulin polyclonal antibody was evaluated by Western blotting with the total protein of RH strain, ME49 strain, and PRU strain of T. gondii, respectively. The results showed that beta-tubulin of T. gondii stains (GT1 and ME49) shared 100% amino-acid sequence identity, and there was 98% amino acid homology between T. gondii and human. The main variable region was the C-terminus. After the fifth immunization, the titers of polyclonal antibody reached 1 : 52,800. Western blotting result indicated that the specific-beta-tubulin polyclonal antibody reacted with beta-tubulin in all the three strains (RH, ME49, and PRU), respectively.

Three genes encoding citrate synthases in Saccharopolyspora erythraea are regulated by the global nutrient-sensing regulators GlnR, DasR, and CRP.

Saccharopolyspora erythraea has three citrate synthases encoded by gltA-2, citA, and citA4. Here, we characterized and identified the expression and regulatory properties of these synthases. Three pleiotropic global regulatory proteins of S. erythraea - CRP, GlnR, and DasR - are involved in carbon metabolism, nitrogen metabolism, and amino-sugar (chitin and GlcNAc) metabolism. Using electrophoretic mobility shift assays (EMSAs), we identified these regulators as proteins that bind directly to the promoter regions of all citrate synthase genes (gltA-2, citA, and citA4). Footprinting assays indicated the exact protect sequences of CRP, GlnR, and DasR on the promoter region of gltA-2, revealing binding competition between GlnR and DasR. Moreover, by comparing the transcription levels of citrate synthase genes between parental and glnR mutant or dasR mutant strains, or by comparing the transcription response of citrate synthases under various nutrient conditions, we found that GlnR and DasR negatively regulated citA and citA4 transcription but had no regulatory effects on the gltA-2 gene. Although no CRP mutant was available, the results indicated that CRP was a cAMP-binding receptor affecting gltA-2 transcription when the intracellular cAMP concentration increased. Thus, an overall model of CS regulation by C and/or N metabolism regulators and cAMP receptor protein was proposed.

GlnR-mediated regulation of nitrogen metabolism in the actinomycete Saccharopolyspora erythraea.

Nitrogen source sensing, uptake, and assimilation are central for growth and development of microorganisms which requires the participation of a global control of nitrogen metabolism-associated genes at the transcriptional level. In soil-dwelling antibiotic-producing actinomycetes, this role is played by GlnR, an OmpR family regulator. In this work, we demonstrate that SACE_7101 is the ortholog of actinomycetes' GlnR global regulators in the erythromycin producer Saccharopolyspora erythraea. Indeed, the chromosomal deletion of SACE_7101 severely affects the viability of S. erythraea when inoculated in minimal media supplemented with NaNO3, NaNO2, NH4Cl, glutamine, or glutamate as sole nitrogen source. Combination of in silico prediction of cis-acting elements, subsequent in vitro (through gel shift assays) and in vivo (real-time reverse transcription polymerase chain reaction) validations of the predicted target genes revealed a very large GlnR regulon aimed at adapting the nitrogen metabolism of S. erythraea. Indeed, enzymes/proteins involved in (i) uptake and assimilation of ammonium, (ii) transport and utilization of urea, (iii) nitrite/nitrate, (iv) glutamate/glutamine, (v) arginine metabolism, (vi) nitric oxide biosynthesis, and (vii) signal transduction associated with the nitrogen source supplied have at least one paralog gene which expression is controlled by GlnR. Our work highlights a GlnR-binding site consensus sequence (t/gna/cAC-n6-GaAAc) which is similar although not identical to the consensus sequences proposed for other actinomycetes. Finally, we discuss the distinct and common features of the GlnR-mediated transcriptional control of nitrogen metabolism between S. erythraea and the model organism Streptomyces coelicolor.

Acetyl coenzyme A synthetase is acetylated on multiple lysine residues by a protein acetyltransferase with a single Gcn5-type N-acetyltransferase (GNAT) domain in Saccharopolyspora erythraea.

Reversible lysine acetylation (RLA) is used by cells of all domains of life to modulate protein function. To date, bacterial acetylation/deacetylation systems have been studied in a few bacteria (e.g., Salmonella enterica, Bacillus subtilis, Escherichia coli, Erwinia amylovora, Mycobacterium tuberculosis, and Geobacillus kaustophilus), but little is known about RLA in antibiotic-producing actinomycetes. Here, we identify the Gcn5-like protein acetyltransferase AcuA of Saccharopolyspora erythraea (SacAcuA, SACE_5148) as the enzyme responsible for the acetylation of the AMP-forming acetyl coenzyme A synthetase (SacAcsA, SACE_2375). Acetylated SacAcsA was deacetylated by a sirtuin-type NAD(+)-dependent consuming deacetylase (SacSrtN, SACE_3798). In vitro acetylation/deacetylation of SacAcsA enzyme was studied by Western blotting, and acetylation of lysine residues Lys(237), Lys(380), Lys(611), and Lys(628) was confirmed by mass spectrometry. In a strain devoid of SacAcuA, none of the above-mentioned Lys residues of SacAcsA was acetylated. To our knowledge, the ability of SacAcuA to acetylate multiple Lys residues is unique among AcuA-type acetyltransferases. Results from site-specific mutagenesis experiments showed that the activity of SacAcsA was controlled by lysine acetylation. Lastly, immunoprecipitation data showed that in vivo acetylation of SacAcsA was influenced by glucose and acetate availability. These results suggested that reversible acetylation may also be a conserved regulatory posttranslational modification strategy in antibiotic-producing actinomycetes.