• Journal of Microbiology and Biotechnology
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• 제33권3호
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• pp.310-318
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• 2023

Microalgae are attracting much attention as promising, eco-friendly producers of bioenergy due to their fast growth, absorption of carbon dioxide from the atmosphere, and production capacity in wastewater and salt water. However, microalgae can only accumulate large quantities of lipid in abiotic stress, which reduces productivity by decreasing cell growth. In this study, the strategy was investigated to increase cell viability and lipid production by overexpressing S-adenosylmethionine (SAM) synthetase (SAMS) in the microalga Chlamydomonas reinhardtii. SAM is a substance that plays an important role in various intracellular biochemical reactions, such as cell proliferation and stress response, and the overexpression of SAMS could allow cells to ithstand the abiotic stress and increase productivity. Compared to wild-type C. reinhardtii, recombinant cells overexpressing SAMS grew 1.56-fold faster and produced 1.51-fold more lipids in a nitrogen-depleted medium. Furthermore, under saline-stress conditions, the survival rate and lipid accumulation were 1.56 and 2.04 times higher in the SAMS-overexpressing strain, respectively. These results suggest that the overexpression of SAMS in recombinant C. reinhardtii has high potential in the industrial-scale production of biofuels and various other high-value-added materials.

• Archives of Pharmacal Research
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• 제21권6호
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• pp.790-792
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• 1998

• Journal of Applied Biological Chemistry
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• 제62권1호
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• pp.1-6
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• 2019

Flavonoid인 isokaempferide는 간 보호, 항균, 항증식성, 항염 등 다양한 생리활성을 가지는 것을 보고 되고 있으며 Amburana cearensis와 Cirsium rivulare (Jacq.)과 같은 식물에서 추출하여 사용한다. 생물전환은 비교적 값이 싼 물질로부터 고부가가치 물질을 얻기 위한 방법으로 유용물질의 식물추출법을 대체할 수 있는 방법이다. Naringenin으로부터 isokaempferide를 생합성 하기 위해 대장균에 포플러에서 분리한 PFLS와 벼에서 분리한 ROMT-9 유전자를 도입하였다. 이 균주를 이용하여 naringenin으로부터 isokaempferide의 생합성 수율(9.8 mg/L)은 낮았다. Isokaempferide의 생합성 수율을 높이기 위해 S-adenosylmethionine (SAM) 생합성 경로의 transcriptional regulator인 MetJ를 제거함으로써 methyl donor로 사용되는 SAM을 증가시켰다. SAM생합성 대사를 조절한 대장균을 이용하여 생물전환 균주의 최적 세포밀도 및 최적의 기질공급 농도를 결정하였다. 최적화된 조건을 이용하여 isokaempferide의 생합성은 87 mg/L까지 증가하였다.

• Journal of Nutrition and Health
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• 제40권1호
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• pp.14-23
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• 2007

Elevated plasma homocysteine (Hcy) is a risk factor for cognitive dysfunction and Alzheimer disease, although the mechanism is still unknown. Both folate and betaine, a choline metabolite, play essential roles in the remethylation of Hcy to methionine. Choline deficiency may be associated with low folate status and high plasma Hcy. Alterations in DNA methylation also have established critical roles for methylation in development of the nervous system. This study was undertaken to assess the effect of choline and folate deficiency on Hcy metabolism and genomic DNA methylation status of the liver and brain. Groups of adult male Sprague Dawley rats were fed on a control, choline-deficient (CD), folate-deficient (FD) or choline/folate-deficient (CFD) diets for 8 weeks. FD resulted in a significantly lower hepatic folate (23%) (p<0.001) and brain folate (69%) (p<0.05) compared to the control group. However, plasma and brain folate remained unaltered by CD and hepatic folate reduced to 85% of the control by CD (p<0.05). Plasma Hcy was significantly increased by FD $(18.34{\pm}1.62{\mu}M)$ and CFD $(19.35{\pm}3.62{\mu}M)$ compared to the control $(6.29{\pm}0.60{\mu}M)$ (p<0.001), but remained unaltered by CD. FD depressed S-adenosylmethionine (SAM) by 59% (p<0.001) and elevated S-adenosylhomocysteine (SAM) by 47% in liver compared to the control group (p<0.001). In contrast, brain SAM levels remained unaltered in CD, FD and CFD rats. Genomic DNA methylation status was reduced by FD in liver (p<0.05) Genomic DNA hypomethylation was also observed in brain by CD, FD and CFD although it was not significantly different from the control group. Genomic DNA methylation status was correlated with folate stores in liver (r=-0.397, p<0.05) and brain (r = -0.390, p<0.05), respectively. In conclusion, our data demonsoated that genomic DNA methylation and SAM level were reduced by folate deficiency in liver, but not in brain, and correlated with folate concentration in the tissue. The fact that folate deficiency had differential effects on SAM, SAH and genomic DNA methylation in liver and brain suggests that the Hcy metabolism and DNA methylation are regulated in tissue-specific ways.

• Nutrition Research and Practice
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• 제9권2호
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• pp.144-149
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• 2015

BACKGROUND/OBJECTIVE: The aim of this study was to examine the effect of high dietary methionine (Met) consumption on plasma and hepatic oxidative stress and dyslipidemia in chronic ethanol fed rats. MATERIALS/METHODS: Male Wistar rats were fed control or ethanol-containing liquid diets supplemented without (E group) or with DL-Met at 0.6% (EM1 group) or 0.8% (EM2 group) for five weeks. Plasma aminothiols, lipids, malondialdehyde (MDA), alanine aminotransferase (ALT), and aspartate aminotransferase were measured. Hepatic folate, S-adenosylmethionine (SAM), and S-adenosylhomocysteine (SAH) were measured. RESULTS: DL-Met supplementation was found to increase plasma levels of homocysteine (Hcy), triglyceride (TG), total cholesterol (TC), and MDA compared to rats fed ethanol alone and decrease plasma ALT. However, DL-Met supplementation did not significantly change plasma levels of HDL-cholesterol, cysteine, cysteinylglycine, and glutathione. In addition, DL-Met supplementation increased hepatic levels of folate, SAM, SAH, and SAM:SAH ratio. Our data showed that DL-Met supplementation can increase plasma oxidative stress and atherogenic effects by elevating plasma Hcy, TG, and TC in ethanol-fed rats. CONCLUSION: The present results demonstrate that Met supplementation increases plasma oxidative stress and atherogenic effects by inducing dyslipidemia and hyperhomocysteinemia in ethanol-fed rats.

• KSBB Journal
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• 제23권6호
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• pp.519-524
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• 2008

Monacolin-K는 Monascus sp.로부터 polyketide pathway를 통해 생합성 되는 이차대사산물로써 강력한 콜레스테롤 저하제로 알려져 있다. 본 연구에서는 monacolin-K의 생합성 경로에 대한 이해에 근거한 지속적인 rational screening을 통해 monacolin-K의 생산성을 향상시킬 수 있었는데 그 중에서 특히 monacolin-K 생합성에 관련된 전구체를 최적화된 생산배지에 첨가함으로써 monacolin-K 생산성이 대조군에 비해 눈에 띠게 증가하는 결과를 확인하였다. 황의 동화작용에서 cysteine이 여러 단계를 거쳐 S-adenosylmethionine (SAM)으로 전환된다는 연구결과와 더불어, SAM은 다양한 세포내에서 주된 methyl donor 역할을 하므로 monacolin-K 구조에 포함되어있는 많은 methyl기 역시 SAM으로부터 유래한다고 알려져 있다. 따라서 첨가한 cysteine이 SAM을 생합성하는데 이용된 것으로 보고 SAM을 생산균주 내에서 고농도로 생산한다면 monacolin-K 생산성이 증가할 것이라 기대하였다. 따라서 여러 균주에서 보고된 SAM synthetase 유전자를 cloning하여 생산균주 내로 도입함으로써 생산균주가 cysteine의 별도첨가 없이도 세포내에서 SAM을 고농도로 생산하도록 하여 monacolin-K의 생산성 향상을 꾀하고자 하였다. 이를 위해 염기서열이 밝혀진 균사형성 곰팡이인 Aspergillus nidulans로부터 SAM synthetase를 암호화하는 metK 유전자를 cloning하고 Monascus 유래의 gpdA promoter에 의해 발현되도록 하는 재조합 발현벡터 pBMmetK를 제작하였고 이를 생산균주 내로 도입하여 형질전환체와 대조군의 monacolin-K 생산성을 확인한 결과, 대조군에 비해 형질전환체에서 Monacolin-K 생산성이 약 3.3배가량 증가한 것을 관찰하였다. 이는 metK 유전자가 생산균주의 DNA 내로 삽입되어 안정적으로 발현됨으로써 세포내에서 많은 methyl 기를 제공함으로써 monacolin-K 생산성이 향상된 것으로 판단되며, 현재는 분자적 수준에서 이러한 형질전환체 내에서 metK 유전자의 발현 정도를 확인하는 중이다.

• Bulletin of the Korean Chemical Society
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• 제26권11호
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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.

• Nutrition Research and Practice
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• 제3권2호
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• pp.122-127
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• 2009

Folate is generally considered as a safe water-soluble vitamin for supplementation. However, we do not have enough information to confirm the potential effects and safety of folate supplementation and the interaction with vitamin $B_{12}$ deficiency. It has been hypothesized that a greater methyl group supply could lead to compensation for vitamin $B_{12}$ deficiency. On this basis, the present study was conducted to examine the effects of high-dose folic acid (FA) supplementation on biomarkers involved in the methionine cycle in vitamin $B_{12}$-deficient rats. Sprague-Dawley rats were fed diets containing either 0 or $100{\mu}g$ (daily dietary requirement) vitamin $B_{12}/kg$ diet with either 2 mg (daily dietary requirement) or 100 mg FA/kg diet for six weeks. Vitamin $B_{12}$-deficiency resulted in increased plasma homocysteine (p<0.01), which was normalized by dietary supplementation of high-dose FA (p<0.01). However, FA supplementation and vitamin $B_{12}$ deficiency did not alter hepatic and brain S-adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH) concentrations and hepatic DNA methylation. These results indicated that supplementation of high-dose FA improved homocysteinemia in vitamin $B_{12}$-deficiency but did not change SAM and SAH, the main biomarkers of methylating reaction.

• 생명과학회지
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• 제21권1호
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• pp.96-101
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• 2011

ATP와 L-methionine으로부터 SAM synthetase (MetK)에 의해 생합성 되는 S-adenosylmethionine (SAM)은 세포내 메틸화에 필요한 메틸기를 제공하는 중심적인 공급체의 역할을 할뿐만 아니라 방선균에서는 일차 및 이차대사산물의 생산 조절에 관여하고 있다는 사실이 밝혀졌다. 이에 논 연구에서는 산업적으로 매우 중요한 항진균성 항생물질인 natamycin을 생산하는 S. natalensis로부터 SAM synthetase 코드하는 metK 유전자를 클로닝하고 동정하였다. S. natalensis에서 클로닝된 metK는 1,209 bp의 염기를 가진 유전자로써 아미노산서열에서 S. pristinaespiralis ATCC 25486과 S. peucetius ATCC 27952의 MetK와 96%, S. violaceusniger Tu 4113과 95% 일치하는 매우 높은 상동성을 보였다. 또 pSET152ET 벡터를 이용해 구축한 metK 고발현용 재조합 플라스미드 pCD1를 S. lividans TK24의 genomic DNA에 도입하여 actinorhodin 생산 유도를 시도해 본 결과 R5 고체배지에서 pCD1이 도입되지 않은 균주에서는 actinorhodin 생산을 전혀 확인할 수 없었지만 pCD1이 도입된 형질전환체에서는 actinorhodin 생산이 강하게 유도되었으며 R4 액체배지에서는 actinorhodin 생산량이 10배 증가되었다. 따라서 본 연구를 통해 클로닝된 S. natalensis 유래 metK 유전자는 방선균에서 이차대사산물의 생산을 유도할 수 있음을 확인할 수 있었다.

• Molecules and Cells
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• 제46권12호
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• pp.736-742
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• 2023

NifB, a radical S-adenosylmethionine (SAM) enzyme, is pivotal in the biosynthesis of the iron-molybdenum cofactor (FeMo-co), commonly referred to as the M-cluster. This cofactor, located within the active site of nitrogenase, is essential for the conversion of dinitrogen (N₂) to NH₃. Recognized as the most intricate metallocluster in nature, FeMo-co biosynthesis involves multiple proteins and a sequence of steps. Of particular significance, NifB directs the fusion of two [Fe₄S₄] clusters to assemble the 8Fe core, while also incorporating an interstitial carbide. Although NifB has been extensively studied, its molecular mechanisms remain elusive. In this review, we explore recent structural analyses of NifB and provide a comprehensive overview of the established catalytic mechanisms. We propose prospective directions for future research, emphasizing the relevance to biochemistry, agriculture, and environmental science. The goal of this review is to lay a solid foundation for future endeavors aimed at elucidating the atomic details of FeMo-co biosynthesis.