• Proceedings of the Korean Society of Grassland Science Conference
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• 2005.06a
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• pp.178-179
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• 2005

• Bulletin of the Korean Chemical Society
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• v.26 no.11
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• pp.1695-1700
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• 2005

Catechol-O-methyltransferase (COMT, EC 2.1.1.6) is an S-adenosylmethionine (SAM, AdoMet) dependent methyltransferase, and is related to the functions of the neurotransmitters in various mental processes, such as Parkinson’s disease. COMT inhibitors represent a new class of antiparkinson drugs, when they are coadministered with levodopa. Based on x-ray structure of rat COMT (rCOMT), the three dimensional structure of human COMT (hCOMT) was constructed by comparative homology modeling using MODELLER. The catalytic site of these two proteins showed subtle differences, but these differences are important to determine the characterization of COMT inhibitor. Ligand docking study is carried out for complex of hCOMT and COMT inhibitors using AutoDock. Among fifteen inhibitors chosen from world patent, nine models were energetically favorable. The average value of heavy atomic RMSD was 1.5 $\AA$. Analysis of ligand-protein binding model implies that Arg201 on hCOMT plays important roles in the interactions with COMT inhibitors. This study may give insight to develop new ways of antiparkinson drug.

• Parasites, Hosts and Diseases
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• v.55 no.2
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• pp.109-114
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• 2017

Protein arginine methyltransferase (PRMT) is an important epigenetic regulator in eukaryotic cells. During encystation, an essential process for Acanthamoeba survival, the expression of a lot of genes involved in the encystation process has to be regulated in order to be induced or inhibited. However, the regulation mechanism of these genes is yet unknown. In this study, the full-length 1,059 bp cDNA sequence of Acanthamoeba castellanii PRMT1 (AcPRMT1) was cloned for the first time. The AcPRMT1 protein comprised of 352 amino acids with a SAM-dependent methyltransferase PRMT-type domain. The expression level of AcPRMT1 was highly increased during encystation of A. castellanii. The EGFP-AcPRMT1 fusion protein was distributed over the cytoplasm, but it was mainly localized in the nucleus of Acanthamoeba. Knock down of AcPRMT1 by synthetic siRNA with a complementary sequence failed to form mature cysts. These findings suggested that AcPRMT1 plays a critical role in the regulation of encystation of A. castellanii. The target gene of AcPRMT1 regulation and the detailed mechanisms need to be investigated by further studies.

• The Korean Journal of Pharmacology
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• v.32 no.2
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• pp.159-168
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• 1996

To determine the regulatory mechanism of phenylethanolamine N-methyltransferase (PNMT) in the adrenal gland and in central nervous system, we observed the change of enzyme activity and mRNA level of PNMT in the adrenal gland, the brain stem, and hypothalamus of rats, which were injected with two neuroleptic agents(reserpine and haloperidol ). Reserpine depleting catecholamines in presynaptic vesicle increased PNMT activities in the adrenal gland and the brain stem to 150% of the control in time-dependent manner, but not in the hypothalamus. Haloperidol blocking dopamine receptor decreased PNMT activities in the adrenal gland and the hypothalamus, but not in the brain stem. Thus, the results indicate that catecholamines inhibit synthesis of epinephrine in the brain stem and the adrenal gland, and that dopamine stimulates synthesis of epinephrine in the hypothalamus and the adrenal gland. In addition, since the change of mRNA levels were nearly in accordance with the change of activities, the transcriptional regulation of PNMT is considered the mechanism of the regulation of epinephrine neuron.

• Journal of Microbiology and Biotechnology
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• v.29 no.7
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• pp.1137-1143
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• 2019

Hepatitis E virus (HEV) accounts for 20 million infections in humans worldwide. In most cases, the infections are self-limiting while HEV genotype 1 infection cases may lead to lethal infections in pregnant women (~ 20% fatality). The lack of small animal models has hampered detailed analysis of virus-host interactions and HEV-induced pathology. Here, by employing a recently developed culture-adapted HEV, we demonstrated that methyltransferase, a non-structural protein, strongly inhibits melanoma differentiation-associated gene 5 (MDA5)-mediated activation of type I interferon responses. Compared to uninfected controls, HEV-infected cells display significantly lower levels of $IFN-{\beta}$ promoter activation when assessed by luciferase assay and RT-PCR. HEV genome-wide screening showed that HEV-encoded methyltransferase (MeT) strongly inhibits MDA5-mediated transcriptional activation of $IFN-{\beta}$ and $NF-{\kappa}B$ in a dose-responsive manner whether or not it is expressed in the presence/absence of a tag fused to it. Taken together, current studies clearly demonstrated that HEV MeT is a novel antagonist of MDA5-mediated induction of $IFN-{\beta}$ signaling.

• Journal of Applied Biological Chemistry
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• v.44 no.3
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• pp.119-124
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• 2001

NTR1 gene of Brassica campestris L. ssp. perkinensis encodes a floral nectary-specific methyltransferase. In this study, the NTR1 cDNA was expressed in E. coli to examine the enzymatic characteristics of the protein product. The GST-NTR1 fusion protein was purified to near homogeneity, showing that the size of NTR1 was 44 kDa. The protein reacted specifically with jasmonic acid (JA), consuming methyl group from S-adenosyl-L-methionine (SAM). GC-MS analysis revealed that the compound produced was authentic methyl jasmonate (MeJA), suggesting that NTR1 is an S-adenosyl-L-methionine: jasmonic acid carboxyl methyltransferase. Km values of NTR1 for JA and SAM were 38.0 and $6.4{\mu}M$, respectively. Optimal activity of the NTR1 was observed at $20^{\circ}C$, pH 7.5, in the presence of 100-150 mM KCl. Thus, kinetic properties, thermal characteristics, optimal pH, and ion-dependency of the NTR1 activity were almost identical to those of Arabidopsis JA methyltransferase JMT, indicating that these two proteins are orthologues of each other.

• BMB Reports
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• v.35 no.3
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• pp.348-351
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• 2002

AquI DNA methyltransferase, M.AquI, catalyses the transfer of a methyl group from S-adenosyl-L-methionine to the C5 position of the outermost deoxycytidine base in the DNA sequence 5'CYCGRG3'. M.AquI is encoded by two overlapping ORFs (termed $\alpha$ and $\beta$) instead of the single ORF that is customary for Class II methyltransferase genes. The structural organization of the M.AquI protein sequence is quite similar to that of other bacterial C5-DNA methyltransferases. Ten conserved motifs are also present in the correct order, but only on two polypeptides. We separately subcloned the genes that encode the $\alpha$ and $\beta$ subunits of M.AquI into expression vectors. The overexpressed His-fusion $\alpha$ and $\beta$ subunits of the enzyme were purified to homogeneity in a single step by Nickel-chelate affinity chromatography. The purified recombinant proteins were assayed for biological activity by an in vitro DNA tritium transfer assay. The $\alpha$ and $\beta$ subunits of M.AquI alone have no DNA methyltransferase activity, but when both subunits are included in the assay, an active enzyme that catalyses the transfer of the methyl group from S-adenosyl-L-methionine to DNA is reconstituted. We also showed that the $\beta$ subunit alone contains all of the information that is required to generate recognition of specific DNA duplexes in the absence of the $\alpha$ subunit.

• Mycobiology
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• v.47 no.4
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• pp.441-448
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• 2019

Two new SAM-dependent methyltransferase encoding genes (fvsmt1 and fvsmt2) were identified from the genome of Flammulina velutipes. In order to make a comprehensive characterization of both genes, we performed in silico analysis of both genes and used qRT-PCR to reveal their expression patterns during the development of F. velutipes. There are 4 and 6 exons with total length of 693 and 978 bp in fvsmt2 and fvsmt1, respectively. The deduced proteins, i.e., FVSMT1 and FVSMT2 contained 325 and 230 amino acids with molecular weight 36297 and 24894 Da, respectively. Both proteins contained a SAM-dependent catalytic domain with signature motifs (I, p-I, II, and III) defining the SAM fold. SAM-dependent catalytic domain is located either in the middle or at the N-terminal of FVSMT2 and FVSMT1, respectively. Alignment and phylogenic analysis showed that FVSMT1 is a homolog to a protein-arginine omega-N-methyltransferase, while FVSMT2 is of cinnamoyl CoA O-methyltransferase type and predicted subcellular locations of these proteins are mitochondria and cytoplasm, respectively. qRT-PCR showed that fvsmt1 and fvsmt2 expression was regulated in different developmental stages. The maximum expression levels of fvsmt1 and fvsmt2 were observed in stipe elongation, while no difference was found in mycelium and pileus. These results positively demonstrate that both the methyltransferase encoding genes are involved in the stipe elongation of F. velutipes.

• Development and Reproduction
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• v.1 no.2
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• pp.117-124
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• 1997

Guanidinoacetate N-methyltransferase (GAMT) catalyzes the last step of creatine biosynthesis and the resultant creatine plays an important role in cellular energy metabolism. GAMT is mainly found in liver, kidney as well as testis and epididymis. We have localized the site of creatine biosynthesis in mouse epididymis by immunoperoxidase staining of GAMT using anti-GAMT antibody. Gamt is extensively expressed in the microvilli of epididymal epithelial cells and also expressed weakly in the cyto plasm of the cells. The staining of GAMT was most prominent in the microvilli of proximal caput epididymis and the intensity was progressively diminished as the epididymal tubule proceeds toward caudal part. The result suggests that GAMT or Cr might be involved in sperm function and/or maturation process in epididymis.

• Biomedical Science Letters
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• v.11 no.4
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• pp.473-479
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• 2005

Possible mechanism of decreased catechol-O-methyltransferase (COMT) activity in cholestatic rat liver was studied. Hepatic and serum COMT activities were determined from the experimental rats with common bile duct ligation (CBDL). The Michaelis-Menten constants in this hepatic enzyme were also measured. The activities of cytosolic, mitochondrial and mircosomal COMT as well as their Vmax values were found to be decreased significantly in CBDL plus taurocholic acid (TCA) injected group than in the control group, such as CBDL alone groups. However, their Km values in the experimental groups did not vary. Serum COMT activity increased slightly in the CBDL plus TCA injected group than in the control group. The above results suggest that TCA represses biosynthesis of the COMT in the liver. The elevated activity of the serum COMT is believed to be caused by the increment of membrane permeability of hepatocytes upon TCA mediated liver cell necrosis.