• YAKHAK HOEJI
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• v.38 no.4
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• pp.430-439
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• 1994

S-Adenosyl-L-methionine synthetase (ATP: methionine S-Adenosyltransferase, EC 2.5.1.6; AdoMet synthetase) catalyzes the biosynthesis of S-Adenosyl-L-methionine(AdoMet) from methionine in the presence of ATP. To elucidate the role of transmethylation reaction in the pancreatic tissues, we examined AdoMet synthetase and isozyme activities, and AdoMet contents in the various tissues. The activities of AdoMet synthetase marked the highest in the kidney, and the lowest in the testis among the various tissues of rat. Considerable amounts of AdoMet synthetase activities were detected in the pancreatic tissues of various animals except for those of frog. The level of ${\alpha}$ and ${\gamma}$ isozyme activities were present in the pancreatic tissues of various animals, while ${\beta}$ isozyme activities were detected as trace. AdoMet synthetase activities of rat brain, liver, testis were decreased with growth. In the rat pancreatic tissues, AdoMet synthetase activities were increased during 16 days after birth and then decreased between 16 and 47 days of age. Levels of AdoMet contents of rat brain and testis were decreased with growth. However, AdoMet contents of rat pancreas were decreased until 26 days of age, and then increased thereafter. AdoMet synthetase isozyme patterns did not vary with growth in the pancreas and testis. But, in the liver, ${\beta}$ form is strikingly increased with growth.

• Proceedings of the Botanical Society of Korea Conference
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• 1999.04a
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• pp.14-14
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• 1999

• Journal of Life Science
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• v.21 no.1
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• pp.96-101
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• 2011

S-Adenosyl-L-methionine synthtase (SAM-s) catalyzes the biosynthesis of SAM from ATP and L-methionine. SAM plays important roles in the primary and secondary metabolism of cells. A metK encoding a SAM-s was searched from Streptomyces natalensis producing natamycin, a predominantly a strong antifungal agent, inhibiting the growth of both yeasts and molds and preventing the formation of aflatoxin in filamentous fungi. To obtain the metK of S. natalensis, PCR using primers designed from the two highly conserved regions for metK genes of Streptomyces strains was carried out, and an intact 1.2-kb metK gene of S. natalensis was cloned by genomic Southern hybridization with PCR product as a probe. To identify the function of the cloned metK gene, it was inserted into pSET152ET for its high expression in the Streptomyces strain, and then introduced into S. lividans TK24 as a host by transconjugation using E. coli ET12567(pUZ8002). The high expression of metK in S. lividans TK24 induced actinorhodin production on R5 solid medium, and its amount in R4 liquid medium was 10-fold higher than that by exconjugant including only pSET152ET.

• 한국생물공학회:학술대회논문집
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• 2005.10a
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• pp.301-304
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• 2005

S-Adenosyl-L-Methionine(SAM) has an important role for DNA methylation and cell signaling. SAM was synthesized from methionine and ATP by SAM synthetase and play an pivotal function in the primary and secondary metabolism of cells. Recent studies have revealed in the effect of SAM in case of morphological differentiation in both eukaryotes and prokaryotes. We isolated SAM gene from Saccharomyces cerevisiae and cloned it into expression vector for E. coli respectively. An 1.15 kb SAM-s gene fragment was isolated by Low-strigency PCR using ORF primer. By the analysed primary sequence deduced from DNA sequence, this gene included conserved domains similar with other well-known SAM synthetase. First of all, SAM synthetase gene cloned pGEM-T vector and subcloned into histidine tagging system to purify the expressed protein using metal chelating resin. Typical characteristic analysis of this enzyme is underway.

• YAKHAK HOEJI
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• v.36 no.1
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• pp.66-72
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• 1992

In order to test relationships between hepatotoxicity and transmethylation, activities of protein methylases and SAM (S-adenosyl-L-methionine)-synthetase were examined in liver tissues of rats treated with $CCl_4$. Also the concentrations of SAM and SAH were measured by HPLC in rat liver. The results are as follows. (1). Activities of protein methylases were not significantly changed in 24 hours after $CCl_4$ treatment. However, in 48 hours, activities of protein methylases were significantly increased in comparison with that of control. (2). Activity of SAM-synthetase was increased steadily in the time course after $CCl_4$ treatment. (3). S-adenosyl-L-methionine concentration of liver tissues in $CCl_4$-treated group was elevated in 24 hours, and then declined thereafter. But the SAH concentration was slightly decreased in the time course after $CCl_4$ treatment. These results indicate that SAM was very actively used in transmethylation reactions of $CCl_4$ damaged rat liver, suggesting the strong relationships between hepatotoxicity and transmethylation phenomena.

• Journal of Microbiology and Biotechnology
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• v.16 no.7
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• pp.1154-1157
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• 2006

It is known that overexpression of S-adenosyl-L-methionine (SAM) synthetase or exogenous addition of SAM enhances the production of actinorhodin, one of pigmented antibiotics found from Streptomyces coelicolor. In order to discover a novel compound as a signal molecule to produce actinorhodin instead of SAM, several compounds were synthesized based on the relationships between structures of the SAM analogues and their actinorhodin productivities. Of these, a few compounds showed better productivities of actinorhodin than SAM.

• Proceedings of the Botanical Society of Korea Conference
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• 2002.04a
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• pp.73-82
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• 2002

The committing step in Met and S-adenosyl-L-methionine (SAM) synthesis is catalyzed by cystathionine ${\gamma}$ -synthase (CGS). Transgenic Arabidopsis thaliana overexpressing CGS under control of 35S promoter show increased soluble Met and its metabolite S-methylmethionine, but only at specific stages of development. CGS-overexpressing seedlings are resistant to ethionine. Similar results were obtained with transgenic potato plants overexpressing Arabidopsis CGS. Several of the transgenic lines show silencing of CGS resulting in deformed p]ants with a reduced capacity for reproductive growth similar as transgenic plants by antisense RNA (CGS[-]). Exogenous feeding of Met to the CGS[-] and CGS[+] silenced plants partially restores their growth. Similar morphological deformities are observed in plants cosuppressed for SAM synthetase, even though such plants accumulate 250 fold more soluble Met than wild type and they overexpress CGS. The results suggest that the abnormalities associated with CGS and SAM synthetase silencing are due in part to a reduced ability to produce SAM, and that SAM may be a regulator of CGS expression.

• Journal of Microbiology and Biotechnology
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• v.21 no.12
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• pp.1294-1298
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• 2011

A metK gene encoding S-adenosyl-L-methionine synthetase was cloned from the non-Streptomyces actinomycetes, Actinoplanes teichomyceticus ATCC31121. In order to evaluate the effect of the metK expression on antibiotic production in actinomycetes, an expression vector harboring the metK gene was constructed and introduced into Streptomyces lividans TK24 and A. teichomyceticus, and the antibiotic production of the exconjugants was assessed. As a result, it was determined that the expression of metK induced 17-fold and 2.2-fold increases in actinorhodin production from S. lividans TK24 and teicoplanin production from A. teichomyceticus, respectively, compared with the control strains.

• Molecules and Cells
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• v.37 no.10
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• pp.727-733
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• 2014

Spinosyns A and D are potent ingredient for insect control with exceptional safety to non-target organisms. It consists of a 21-carbon tetracyclic lactone with forosamine and tri-Omethylated rhamnose which are derived from S-adenosyl-methionine. Although previous studies have revealed the involvement of metK1 (S-adenosylmethionine synthetase), rmbA (glucose-1-phosphate thymidylyltransferase), and rmbB (TDP-D-glucose-4, 6-dehydratase) in the biosynthesis of spinosad, expression of these genes into rational screened Saccharopolyspora spinosa (S. spinosa MUV) has not been elucidated till date. In the present study, S. spinosa MUV was developed to utilize for metabolic engineering. The yield of spinosyns A and D in S. spinosa MUV was $244mgL^{-1}$ and $129mgL^{-1}$, which was 4.88-fold and 4.77-fold higher than that in the wild-type ($50mgL^{-1}$ and $27mgL^{-1}$), respectively. To achieve the better production; positive regulator metK1-sp, rmbA and rmbB genes from Streptomyces peucetius, were expressed and co-expressed in S. spinosa MUV under the control of strong $ermE^*$ promoter, using an integration vector pSET152 and expression vector pIBR25, respectively. Here-with, the genetically engineered strain of S. spinosa MUV, produce spinosyns A and D up to $372/217mgL^{-1}$ that is 7.44/8.03-fold greater than that of wild type. This result demonstrates the use of metabolic engineering on rationally developed high producing natural variants for the production.