The lignan glycosyltransferase UGT236(belonging to the UGT71 B family) from Isatis indigotica can catalyze the production of phloridzin from phloretin in vitro. UGT236 shares high identity with P2'GT from apple. In this study, the recombinant plasmid pET28 a-MBP-UGT236 was transferred into Escherichia coli Rosetta(DE3) cells and induced by isopropyl-β-D-thiogalactoside(IPTG). The purified UGT236 protein was used for enzymatic characterization with phloretin as substrate. The results showed that UGT236 had the optimal reaction temperature of 40 ℃ and the optimal pH 8(Na_2HPO_4-NaH_2PO_4 system). The UGT236 activity was inhibited by Ni~(2+) and Al~(3+), enhanced by Fe~(2+), Co~(2+), and Mn~(2+), and did not affected by Mg~(2+), Ca~(2+), Li~+, Na~+, or K~+. The K_m, K_(cat), and K_(cat)/K_m of phloretin were 61.03 μmol·L~(-1), 0.01 s~(-1), and 157.11 mol~(-1)·s~(-1)·L, and those of UDPG were 183.6 μmol·L~(-1), 0.01 s~(-1), and 51.91 mol~(-1)·s~(-1)·L, respectively. The possible active sites were predicted by homologous modeling and molecular docking. By mutagenisis and catalytic activity detection, three key active sites, Glu391, His15, and Thr141, were identified, while Phe146 was related to product diversity. In summary, we found that the lignan glycosyltransferase UGT236 from I.indigotica could catalyze the reaction of phloretin into phloridzin. Several key amino acid residues were identified by structure prediction, molecular docking, and site-mutagenesis, which provided a basis for studying the specificity and diversity of phloretin glycoside products. This study can provide a reference for artificially producing glycosyltransferase elements with high efficiency and specific catalysis.
Glucosyltransferases/genetics* ; Glycosyltransferases/metabolism* ; Isatis ; Lignans/metabolism* ; Molecular Docking Simulation ; Phloretin/metabolism* ; Phlorhizin/metabolism*

Water solubility, stability, and bioavailability, can be substantially improved after glycosylation. Glycosylation of bioactive compounds catalyzed by glycoside hydrolases (GHs) and glycosyltransferases (GTs) has become a research hotspot. Thanks to their rich sources and use of cheap glycosyl donors, GHs are advantageous in terms of scaled catalysis compared to GTs. Among GHs, sucrose phosphorylase has attracted extensive attentions in chemical engineering due to its prominent glycosylation activity as well as its acceptor promiscuity. This paper reviews the structure, catalytic characteristics, and directional redesign of sucrose phosphorylase. Meanwhile, glycosylation of diverse chemicals with sucrose phosphorylase and its coupling applications with other biocatalysts are summarized. Future research directions were also discussed based on the current research progress combined with our working experience.
Glucosyltransferases/metabolism* ; Glycoside Hydrolases/metabolism* ; Glycosylation ; Glycosyltransferases/genetics*

By engineering the subsite +1 of cyclodextrin glycosyltransferase (CGTase) from Paenibacillus macerans, we improved its maltodextrin specificity for 2-O-D-glucopyranosyl-L-ascorbic acid (AA-2G) synthesis. Specifically, we conducted site-saturation mutagenesis on Leu194, Ala230, and His233 in subsite +1 separately and gained 3 mutants L194N (leucine --> asparagine), A230D (alanine --> aspartic acid), and H233E (histidine --> glutamic acid) produced higher AA-2G yield than the wild-type and the other mutant CGTases. Therefore, the 3 mutants L194N, A230D, and H233E were further used to construct the double and triple mutations. Among the 7 obtained combinational mutants, the triple mutant L194N/A230D/H233E produced the highest AA-2G titer of 1.95 g/L, which was increased by 62.5% compared with that produced by the wild-type CGTase. Then, we modeled the reaction kinetics of all the mutants and found a substrate inhibition by high titer of L-AA for the mutants. The optimal temperature, pH, and reaction time of all the mutants were also determined. The structure modeling indicated that the enhanced maltodextrin specificity may be related with the changes of hydrogen bonding interactions between the side chain of residue at the three positions (194, 230 and 233) and the substrate sugars.
Ascorbic Acid ; analogs & derivatives ; chemistry ; Glucosyltransferases ; genetics ; metabolism ; Hydrogen Bonding ; Kinetics ; Mutagenesis, Site-Directed ; Paenibacillus ; enzymology ; Polysaccharides ; chemistry ; Protein Engineering ; Substrate Specificity ; Temperature

OBJECTIVETo investigate whether transcription factor-kappaB (NF-κ B) is involved in the modulation of P-glycoprotein (P-gp) by glucosylceramide synthase (GCS) in a multidrug resistance leukemia cell line K562/A02 and to explore the relationship between NF-κ B and extracelluar signal-regulated kinase (ERK).

METHODSK562/A02 cells were treated with GCSsiRNA, pyrrolidine dithiocarbamate (PDTC, a NF-κ B specific inhibitor) and U0126 (a MEK1/2 inhibitor), respectively. The expression of GCS and multidrug resistance protein 1 (MDR1) mRNA were analyzed with qRT-PCR. Various proteins of different groups were measured by Western blotting.

RESULTSAfter transfected with GCSsiRNA for 48 h, GCS mRNA were reduced by 62% (51%-73%) and MDR1 mRNA was reduced by 52% (43%-61%) in the K562/A02 cells. Compared with the negative control, relative expression of NF-κ B p65 in nuclear and P-ERK1/2 were both down-regulated, and P-gp was also inhibited significantly at 72 h after transfected with GCSsiRNA (P< 0.05). In addition, the expression of P-gp was decreased at 24 h with 80 μ mol/L PDTC and 48 h with 20 μ mol/L PDTC. P-ERK1/2 was inhibited significantly when the cells were treated with 20 μ mol/L U0126 for 48 h. The expression of NF-κ B p65 in nuclear and P-gp were also down-regulated.

CONCLUSIONNF-κ B can modulate the effect of GCS on P-gp in K562/A02 cells. P-ERK1/2 can activate NF-κ B in above signal transduction pathway.

ATP-Binding Cassette, Sub-Family B, Member 1 ; genetics ; metabolism ; Cell Line, Tumor ; Drug Resistance, Multiple ; Drug Resistance, Neoplasm ; Glucosyltransferases ; genetics ; metabolism ; Humans ; K562 Cells ; Leukemia ; genetics ; NF-kappa B ; genetics ; metabolism

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

BACKGROUNDGlucosylceramide synthase (GCS), an enzyme responsible for ceramide glycosylation, plays an important role in multidrug resistance (MDR) in some tumors in vitro; however, its expression and clinicopathological significance in non-small cell lung cancer (NSCLC) remains unclear.

METHODSWe evaluated GCS expression in 116 paired tumor and adjacent non-cancerous tissues and 50 frozen tissues from patients with NSCLC using immunohistochemistry and western blotting, and explored the correlation between GCS and NSCLC clinicopathological characteristics and prognosis. We observed the association between GCS and the MDR proteins P-glycoprotein (P-gp) and lung resistance-related protein (LRP) to determine the link between GCS and MDR at the histological level.

RESULTSGCS expression was significantly upregulated in NSCLC tumors compared with non-cancerous tissue. There was high GCS expression in 75/116 tumor specimens (64.7%) and 16/116 non-cancerous specimens (13.8%). High GCS expression was significantly associated with poor differentiation (P = 0.01), lymph node metastasis (P = 0.004), recurrence/distant metastasis (P = 0.006), and chemotherapy resistance (P = 0.025). Multivariate analysis demonstrated that GCS immunopositivity was an independent risk factor for survival (P = 0.018). P-gp was expressed in 80/116 tumors (69.0%) and in 12/116 non-cancerous tissue specimens (10.3%; P = 0.001); LRP was expressed in 85/116 tumors (73.3%) and 19/116 non-cancerous tissue specimens (16.4%; P = 0.001). Importantly, the results demonstrated that increased GCS expression in NSCLC cancer specimens correlated with increased expression of P-gp and LRP, molecules known to stimulate cancer cell MDR (r = 0.612 and 0.503, P = 0.01 and 0.035, respectively).

CONCLUSIONGCS upregulation might contribute to the development of NSCLC and could be a useful prognostic indicator and chemoresistance predictor for NSCLC patients.

ATP Binding Cassette Transporter, Sub-Family B ; genetics ; metabolism ; Adult ; Aged ; Blotting, Western ; Carcinoma, Non-Small-Cell Lung ; enzymology ; pathology ; Drug Resistance, Multiple ; Female ; Glucosyltransferases ; genetics ; metabolism ; Humans ; Immunohistochemistry ; Male ; Middle Aged

We studied the mutation effect of subsites -3(Lys47), -7(146-152), and cyclization center (Tyr195) in active domain on product specificity of alpha-cyclodextrin glucanotransferase (alpha-CGTase) from Paenibacillus macerans sp. 602-1. The Lys47 was replaced by Thr47 and Tyr195 by Ile195, and the amino acids from 146 to 152 were replaced by Ile (named as delta6). All these mutant alpha-CGTases were actively expressed in E. coli BL21. Compared with the wild-type alpha-CGTase, the starch-degrading activities of all the mutant enzymes were declined. For mutant Y195I, the percentage of alpha-CD was decreased from 68% to 30%, and beta-CD was raised from 22.2% to 33.3%. Interestingly, gamma-CD was increased from 8.9% to 36.7% and became the main product, while the actual yield was increased from 0.4 g/L to 1.1 g/L. Mutant K47T and delta6 still produced alpha-CD as main product though the percentage of beta- and gamma-CD increased. Purified Y195I CGTase showed similar optimum temperature with the wild-type alpha-CGTase, but its optimum pH shifted from 5.0 to 6.0 with better pH stability. In summary, mutant Y195I CGTase has the potential to produce gamma-CD as the main product.
Escherichia coli ; genetics ; metabolism ; Glucosyltransferases ; genetics ; metabolism ; Mutant Proteins ; genetics ; metabolism ; Mutation ; Paenibacillus ; enzymology ; Recombinant Proteins ; genetics ; gamma-Cyclodextrins ; metabolism

BACKGROUNDGlucosylceramide synthase (GCS) can reduce ceramide levels and help cells escape ceramide-induced apoptosis, thus leading to multidrug resistance (MDR). However, its expression and clinical significance in thyroid neoplasms still remain unclear. We aimed to elucidate the expression of GCS and explore its correlation with the clinicopathological characteristics in papillary thyroid carcinomas (PTCs).

METHODSWe retrospectively investigated GCS protein expression level in tissue specimens obtained from 108 consecutive PTC patients by immunohistochemistry and Western blotting.

RESULTSGCS was weakly positive or negative in normal follicular cells, but it was frequently overexpressed in PTC cells. GCS overexpression was associated with primary tumor size, local infiltration, lymph node metastasis, and local recurrence, but not associated with gender, age, pathological variants, tumor multifocality, tumor stage or distant metastasis. Western blotting also showed that GCS protein levels were much higher in PTCs' tissues than in normal thyroid tissues.

CONCLUSIONGCS was upregulated in PTCs and might be an independent factor affecting prognosis.

Adult ; Blotting, Western ; Carcinoma ; enzymology ; Carcinoma, Papillary ; Female ; Glucosyltransferases ; genetics ; metabolism ; Humans ; Immunohistochemistry ; Male ; Prognosis ; Retrospective Studies ; Thyroid Neoplasms ; enzymology ; Up-Regulation

OBJECTIVETo investigate the effect of glucosylceramide synthase (GCS) on P-glycoprotein (P-gp) expression via extracellular signal-regulated kinase (ERK) pathways in leukemia K562/A02 cell line.

METHODSK562/A02 multidrug resistance cells were treated with GCS siRNA and U0126, respectively. Expression of multidrug resistance protein 1 (MDR1) mRNA was analyzed with qRT-PCR. Phosphorylated ERK1/2, total ERK1/2 protein and P-gp in different groups were measured with Western blotting.

RESULTSAfter treated with U0126, P-ERK1/2 was decreased along with the increased U0126 concentration. P-ERK1/2 and P-gp were apparently down-regulated by U0126 at the concentrations of 20 μmol/L, 40 μmol/L and 60 μmol/L. After being transfected with GCS siRNA, GCS mRNA was inhibited by 70.50% (58.00%-76.00%) in K562/A02 cells. Compared with the negative control, both P-ERK1/2 and P-gp were inhibited significantly after RNAi for 72 hours (P<0.01 and P<0.05, respectively.

CONCLUSIONGCS may affect the expression of P-gp by ERK signal transduction pathway in leukemia cells.

ATP-Binding Cassette, Sub-Family B, Member 1 ; biosynthesis ; genetics ; metabolism ; Cell Line, Tumor ; Drug Resistance, Multiple ; Drug Resistance, Neoplasm ; Glucosyltransferases ; metabolism ; Humans ; K562 Cells ; Leukemia ; enzymology ; genetics ; metabolism ; MAP Kinase Signaling System

To investigate the mechanism of high product specificity of gamma-clodextrin glucanotransferase (CGTase) from alkalophilic Bacillus clarkii 7364, we aligned protein sequence and structure model, found out that loss of 6 amino acids at subsite -7 probably affected its product specificity. Using overlapping PCR method, we inserted 6 amino acids into subsite -7 of CGTase. The mutant CGTase gene was ligated with pET-20b (+) and expressed in Escherichia coli BL21 (DE3). The extracellular recombinant enzyme was used to transform soluble starch into cyclodextrins (CDs). HPLC analysis results show that, compared to wild CGTase, the gamma-CDs produced by mutant enzyme decreased from 76.0% to 12.5%, whereas the ratio of alpha- and beta-CDs increased from 8.7% and 15.2% to 37.5% and 50%. The possible mechanism was that, compared to alpha-, beta-CGTase, wild gamma-CGTase lacks 6 amino acids in its subsite -7. This conformation provided more space for glucose combination and was thus advantageous for forming gamma-CD. When the 6 amino acids were inserted into the subsite -7 of wild gamma-CGTase, the space to bind with glucose reduced and consequently resulted in less gamma-CD production.
Bacillus ; enzymology ; genetics ; Escherichia coli ; genetics ; metabolism ; Glucosyltransferases ; biosynthesis ; genetics ; Mutant Proteins ; biosynthesis ; genetics ; Recombinant Proteins ; biosynthesis ; genetics