Bacillus coagulans can utilize the hydrolyzed carbon source of agricultural waste to produce lactic acid via a homofermentative pathway. However, a significant carbon source metabolic repression effect was observed when the strain metabolized mixed sugars (glucose and xylose), reducing the productivity of lactic acid. In this study, we obtained the fermentation conditions for the simultaneous utilization of the mixed sugars by B. coagulans by changing the ratio of glucose to xylose in the medium. Through transcriptome sequencing, several key genes responsible for xylose utilization were identified. The critical role of xylose isomerase (XylA, EC 5.3.1.5) in the synchronous utilization of glucose/xylose in B. coagulans was investigated via qRT-PCR (quantitative real-time polymerase chain reaction). Subsequently, the heterologous expression and characterization of the XylA-encoding gene (XylA) were conducted. It was determined that the gene encoded a protein composed of 440 amino acid residues. The secondary structure of the encoded protein was predominantly composed of α-helixes and random coils, while the higher structure of the protein was identified as a homotetramer. Then, XylA was cloned and expressed in Escherichia coli BL21(DE3), and the recombinant protein Bc-XlyA was obtained with a molecular weight of approximately 50 kDa. The optimal pH and temperature of Bc-XylA were 8.0 and 60 ℃, respectively, and Mn²⁺, Mg²⁺, and Co²⁺ had positive effects on the activity of Bc-XlyA. The present study provides scientific data on the molecular modification of B. coagulans, offering theoretical support for the efficient utilization of xylose in the strain.
Xylose/metabolism* ; Cloning, Molecular ; Bacillus coagulans/enzymology* ; Aldose-Ketose Isomerases/metabolism* ; Fermentation ; Bacterial Proteins/metabolism* ; Glucose/metabolism*

L-arabinose isomerase (L-AI) is the key enzyme that isomerizes D-galactose to D-tagatose. In this study, to improve the activity of L-arabinose isomerase on D-galactose and its conversion rate in biotransformation, an L-arabinose isomerase from Lactobacillus fermentum CGMCC2921 was recombinantly expressed and applied in biotransformation. Moreover, its substrate binding pocket was rationally designed to improve the affinity and catalytic activity on D-galactose. We show that the conversion of D-galactose by variant F279I was increased 1.4 times that of the wild-type enzyme. The K_m and k_cat values of the double mutant M185A/F279I obtained by superimposed mutation were 530.8 mmol/L and 19.9 s^-1, respectively, and the catalytic efficiency was increased 8.2 times that of the wild type. When 400 g/L lactose was used as the substrate, the conversion rate of M185A/F279I reached a high level of 22.8%, which shows great application potential for the enzymatic production of tagatose from lactose.
Galactose/metabolism* ; Limosilactobacillus fermentum/genetics* ; Lactose ; Hexoses/metabolism* ; Aldose-Ketose Isomerases/genetics* ; Hydrogen-Ion Concentration

Protozoan viruses may influence the function and pathogenicity of the protozoa. Trichomonas vaginalis is a parasitic protozoan that could contain a double stranded RNA (dsRNA) virus, T. vaginalis virus (TVV). However, there are few reports on the properties of the virus. To further determine variations in protein expression of T. vaginalis, we detected 2 strains of T. vaginalis; the virus-infected (V⁺) and uninfected (V⁻) isolates to examine differentially expressed proteins upon TVV infection. Using a stable isotope N-terminal labeling strategy (iTRAQ) on soluble fractions to analyze proteomes, we identified 293 proteins, of which 50 were altered in V⁺ compared with V⁻ isolates. The results showed that the expression of 29 proteins was increased, and 21 proteins decreased in V⁺ isolates. These differentially expressed proteins can be classified into 4 categories: ribosomal proteins, metabolic enzymes, heat shock proteins, and putative uncharacterized proteins. Quantitative PCR was used to detect 4 metabolic processes proteins: glycogen phosphorylase, malate dehydrogenase, triosephosphate isomerase, and glucose-6-phosphate isomerase, which were differentially expressed in V⁺ and V⁻ isolates. Our findings suggest that mRNA levels of these genes were consistent with protein expression levels. This study was the first which analyzed protein expression variations upon TVV infection. These observations will provide a basis for future studies concerning the possible roles of these proteins in host-parasite interactions.
Glucose-6-Phosphate Isomerase ; Glycogen Phosphorylase ; Heat-Shock Proteins ; Host-Parasite Interactions ; Malate Dehydrogenase ; Metabolism ; Polymerase Chain Reaction ; Proteome ; Reticuloendotheliosis virus ; Ribosomal Proteins ; RNA, Double-Stranded ; RNA, Messenger ; Trichomonas vaginalis* ; Trichomonas* ; Triose-Phosphate Isomerase ; Virulence

Arabinose-5-phosphate isomerase (KdsD) is the first key limiting enzyme in the biosynthesis of 3-deoxy-D-manno-octulosonate (KDO). KdsD gene was cloned into prokaryotic expression vector pET-HTT by seamless DNA cloning method and the amount of soluble recombinant protein was expressed in a soluble form in E. coli BL21 (DE3) after induction of Isopropyl β-D-1-thiogalactopyranoside (IPTG). The target protein was separated and purified by Ni-NTA affinity chromatography and size exclusion chromatography, and its purity was more than 85%. Size exclusion chromatography showed that KdsD protein existed in three forms: polymers, dimmers, and monomers in water solution, different from microbial KdsD enzyme with the four polymers in water solution. Further, the purified protein was identified through Western blotting and MALDI-TOF MASS technology. The results of activity assay showed that the optimum pH and temperature of AtKdsD isomerase activities were 8.0 and 37 ℃, respectively. The enzyme was activated by metal protease inhibitor EDTA (5 mmol/L) and inhibited by some metal ions at lower concentration, especially with Co²⁺ and Cd²⁺ metal ion. Furthermore, when D-arabinose-5-phosphate (A5P) was used as substrate, Km and Vmax of AtKdsD values were 0.16 mmol/L, 0.18 mmol/L·min. The affinity of AtKdsD was higher than KdsD in E. coli combined with substrate. Above results have laid a foundation for the KdsD protein structure and function for its potential industrial application.
Aldose-Ketose Isomerases ; biosynthesis ; Arabidopsis ; enzymology ; Arabidopsis Proteins ; biosynthesis ; Cloning, Molecular ; Escherichia coli ; metabolism ; Metals ; Pentosephosphates ; Recombinant Proteins ; biosynthesis

After renal injury, selective damage occurs in the proximal tubules as a result of inhibition of glycolysis. The molecular mechanism of damage is not known. Poly(ADP-ribose) polymerase (PARP) activation plays a critical role of proximal tubular cell death in several renal disorders. Here, we studied the role of PARP on glycolytic flux in pig kidney proximal tubule epithelial LLC-PK1 cells using XFp extracellular flux analysis. Poly(ADP-ribosyl)ation by PARP activation was increased approximately 2-fold by incubation of the cells in 10 mM glucose for 30 minutes, but treatment with the PARP inhibitor 3-aminobenzamide (3-AB) does-dependently prevented the glucose-induced PARP activation (approximately 14.4% decrease in 0.1 mM 3-AB-treated group and 36.7% decrease in 1 mM 3-AB-treated group). Treatment with 1 mM 3-AB significantly enhanced the glucose-mediated increase in the extracellular acidification rate (61.1±4.3 mpH/min vs. 126.8±6.2 mpH/min or approximately 2-fold) compared with treatment with vehicle, indicating that PARP inhibition increases only glycolytic activity during glycolytic flux including basal glycolysis, glycolytic activity, and glycolytic capacity in kidney proximal tubule epithelial cells. Glucose increased the activities of glycolytic enzymes including hexokinase, phosphoglucose isomerase, phosphofructokinase-1, glyceraldehyde-3-phosphate dehydrogenase, enolase, and pyruvate kinase in LLC-PK1 cells. Furthermore, PARP inhibition selectively augmented the activities of hexokinase (approximately 1.4-fold over vehicle group), phosphofructokinase-1 (approximately 1.6-fold over vehicle group), and glyceraldehyde-3-phosphate dehydrogenase (approximately 2.2-fold over vehicle group). In conclusion, these data suggest that PARP activation may regulate glycolytic activity via poly(ADP-ribosyl)ation of hexokinase, phosphofructokinase-1, and glyceraldehyde-3-phosphate dehydrogenase in kidney proximal tubule epithelial cells.
Animals ; Cell Death ; Epithelial Cells* ; Glucose ; Glucose-6-Phosphate Isomerase ; Glycolysis ; Hexokinase ; Kidney* ; LLC-PK1 Cells ; Oxidoreductases ; Phosphofructokinase-1 ; Phosphopyruvate Hydratase ; Poly Adenosine Diphosphate Ribose* ; Poly(ADP-ribose) Polymerases* ; Pyruvate Kinase ; Swine

BACKGROUND: The aim of this study was to develop and validate a multiplex real-time PCR assay for simultaneous identification and toxigenic type characterization of Clostridium difficile. METHODS: The multiplex real-time PCR assay targeted and simultaneously detected triose phosphate isomerase (tpi) and binary toxin (cdtA) genes, and toxin A (tcdA) and B (tcdB) genes in the first and sec tubes, respectively. The results of multiplex real-time PCR were compared to those of the BD GeneOhm Cdiff assay, targeting the tcdB gene alone. The toxigenic culture was used as the reference, where toxin genes were detected by multiplex real-time PCR. RESULTS: A total of 351 stool samples from consecutive patients were included in the study. Fifty-five stool samples (15.6%) were determined to be positive for the presence of C. difficile by using multiplex real-time PCR. Of these, 48 (87.2%) were toxigenic (46 tcdA and tcdB-positive, two positive for only tcdB) and 11 (22.9%) were cdtA-positive. The sensitivity, specificity, negative predictive value (NPV), and positive predictive value (PPV) of the multiplex real-time PCR compared with the toxigenic culture were 95.6%, 98.6%, 91.6%, and 99.3%, respectively. The analytical sensitivity of the multiplex real-time PCR assay was determined to be 103colonyforming unit (CFU)/g spiked stool sample and 0.0625 pg genomic DNA from culture. Analytical specificity determined by using 15 enteric and non-clostridial reference strains was 100%. CONCLUSIONS: The multiplex real-time PCR assay accurately detected C. difficile isolates from diarrheal stool samples and characterized its toxin genes in a single PCR run.
ADP Ribose Transferases/genetics ; Bacterial Proteins/*genetics ; Bacterial Toxins/*genetics ; Clostridium difficile/isolation & purification/*metabolism ; DNA, Bacterial/genetics/metabolism ; Enterotoxins/genetics ; Feces/*microbiology ; Humans ; Multiplex Polymerase Chain Reaction ; Prospective Studies ; Real-Time Polymerase Chain Reaction ; Triose-Phosphate Isomerase/genetics

Enzymatic conversion is very important to produce functional rare sugars, but the conversion rate of single enzymes is generally low. To increase the conversion rate, a dual-enzyme coupled reaction system was developed. Dual-enzyme coupled reaction system was constructed using D-psicose-3-epimerase (DPE) and L-rhamnose isomerase (L-RhI), and used to convert D-fructose to D-psicose and D-allose. The ratio of DPE and L-RhI was 1:10 (W/W), and the concentration of DPE was 0.05 mg/mL. The optimum temperature was 60 degrees C and pH was 9.0. When the concentration of D-fructose was 2%, the reaction reached its equilibrium after 10 h, and the yield of D-psicose and D-allose was 5.12 and 2.04 g/L, respectively. Using the dual-enzymes coupled system developed in the current study, we could obtain sugar syrup containing functional rare sugar from fructose-rich raw material, such as high fructose corn syrup.
Aldose-Ketose Isomerases ; metabolism ; Carbohydrate Epimerases ; metabolism ; Fructose ; chemistry ; Glucose ; chemistry ; Hydrogen-Ion Concentration ; Temperature

OBJECTIVETo construct plant expression pCAMBIA1301-PMI by substituting PMI for hygromycin resistance gene in pCAMBIA1301 and obtain transgenic Salvia miltiorrhiza f. alba using PMI-mannose selection system.

METHODThe 6-phosphomannose isomerase gene (PMI) of Escherichia coli was amplified by PCR. Sequence analysis showed that it shared 100% amino acids identities with the sequences of PMI genes isolates reported in the NCBI. Based on pCAMBIA1305, the plant expression pCAMBIA1305-PMI was constructed successfully by substituting PMI for hygromycin resistance gene in pCAMBIA1305. pCAMBIA1305-PMI was transformed into Agrobacterium tumefaciens LBA4404, and then the leaves of S. miltiorrhiza f. alba were inoculated in LBA4404 with pCAMBIA1305-PMI.

RESULTPlant expression pCAMBIA1301-PMI was successfully constructed and the leaves of S. miltiorrhiza f. alba inoculated in LBA4404 with pCAMBIA1305-PMI were selected on medium supplemented with a combination of 20 g x L(-1) mannose and 10 g x L(-1) sucrose as a carbon source. The transformation efficiency rate was 23.7%.

CONCLUSIONGenetic transformation was confirmed by PCR, indicating that a new method for obtaining transgenic S. miltiorrhiza f. alba plants was developed using PMI-mannose selection system.

Anti-Bacterial Agents ; pharmacology ; Biomarkers ; Cinnamates ; pharmacology ; Escherichia coli ; enzymology ; genetics ; Escherichia coli Proteins ; genetics ; metabolism ; Gene Expression ; Genetic Vectors ; genetics ; metabolism ; Hygromycin B ; analogs & derivatives ; pharmacology ; Mannose-6-Phosphate Isomerase ; genetics ; metabolism ; Plants, Genetically Modified ; drug effects ; genetics ; metabolism ; Salvia miltiorrhiza ; drug effects ; genetics ; metabolism ; Transformation, Genetic

Our previous research indicated that the Streptomyces pactum Act12 (Act12) had a certain promotional effect on tanshinone accumulation and up-regulated the expression of genes 3-hydroxy-3-methyglutaryl-CoA reductase (HMGR) and 1-deoxy-d-xylulose-5-phosphate reductoisomerase (DXR) in Salvia miltiorrhiza hairy roots. This study focuses on the roles of reactive oxygen species in S. pactum Act12-induced tanshinone production in S. miltiorrhiza hairy roots. The 4% Act12, 4% Act12 + CAT and 4% Act12 + SOD were added to S. miltiorrhiza hairy root and subcultured for 21 days, the dry weight, contents of reactive oxygen species, contents of tanshinones and expression of HMGR and DXR were determined at different harvest-time. The generation of reactive oxygen species (ROS) in S. miltiorrhiza hairy roots was triggered by 4% Act12 treatment. The relative expressions of genes HMGR and DXR in 4% Act12 treatment were 32.4 and 4.8-fold higher than those in the control. And the total tanshinone in the hairy roots was 10.2 times higher than that of the control. The CAT and SOD could significantly inhibit the ROS accumulation and relative expressions of genes HMGR and DXR in 4% Act12 treatment, which induced the total tanshinone content was decreased by 74.6% comparing with the 4% Act12 treatment. ROS mediated Act12-induced tanshinone production. The Act12 may be via the ROS signal channel to activate the tanshinone biosynthesis pathways. Thereby the tanshinon content in hairy roots was increased.
Aldose-Ketose Isomerases ; genetics ; metabolism ; Diterpenes, Abietane ; biosynthesis ; Plant Proteins ; genetics ; metabolism ; Plant Roots ; enzymology ; genetics ; metabolism ; microbiology ; Reactive Oxygen Species ; metabolism ; Salvia miltiorrhiza ; enzymology ; genetics ; metabolism ; microbiology ; Secondary Metabolism ; Streptomyces ; physiology

Acanthamoeba cysts are resistant to unfavorable physiological conditions and various disinfectants. Acanthamoeba cysts have 2 walls containing various sugar moieties, and in particular, one third of the inner wall is composed of cellulose. In this study, it has been shown that down-regulation of cellulose synthase by small interfering RNA (siRNA) significantly inhibits the formation of mature Acanthamoeba castellanii cysts. Calcofluor white staining and transmission electron microscopy revealed that siRNA transfected amoeba failed to form an inner wall during encystation and thus are likely to be more vulnerable. In addition, the expression of xylose isomerase, which is involved in cyst wall formation, was not altered in cellulose synthase down-regulated amoeba, indicating that cellulose synthase is a crucial factor for inner wall formation by Acanthamoeba during encystation.
Acanthamoeba castellanii/*enzymology/genetics/metabolism ; Aldose-Ketose Isomerases/*biosynthesis ; Amebiasis/*pathology ; Benzenesulfonates ; Cell Wall/chemistry/genetics/*metabolism ; Cellulose/biosynthesis ; Down-Regulation ; Encephalitis/parasitology ; Glucosyltransferases/*biosynthesis/genetics ; Keratitis/parasitology ; Microscopy, Electron, Transmission ; RNA Interference ; RNA, Small Interfering