• Proceedings of the Korean Society of Applied Pharmacology
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• 1996.04a
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• pp.185-185
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• 1996

Nitric oxide synthase(NO Synthase:E.C.1.14.13.39)는 생체내에서 L-arginine을 기질로 하여 citrulline과 nitric oxide(NO)를 생성하는 효소로서, 최근 연구에 의하면 2/3 부분 간 절제술 후 prereplicative phase동안에 발현되는 것으로 알려져 있다. 한편, 생체내에서 NO Synthase에 상경적 길항제인 methylarginine에 관해서도 수년간 많은 연구가 진행되어 왔다. 이들의 생성 기전은 protein methylation에 의해 생성된 methylated protein이 생체 내에서 분해되어 생성된다고 알려져 있으나, 정확한 기전에 대해서는 아직 논란의 여지가 많다. 따라서, 본 연구에서는 In vivo 실험을 통해 부분 간 절제술 후 시간대별로 간 조직에서의 NO Synthase 활성도와 혈청에서 NO의 최종 대사물인 Nitrite/Nitrate를 측정하였으며, 또한 NO Synthase 조절에 관여하는 세포내 기질인 arginine과 억제 인자인 methylarginine함량을 간 조직 및 혈청에서 측정하고, 세포 신호 전달체계에 관여하는 cyclic GMP 함량을 측정함으로써, 부분 간 절제술 후 간 재생동안에 NO Synthase 활성도와 methylarginine 및 arginine과의 상관 관계를 규명하고, 간 재생동안, 생성된 nitric oxide의 역할을 연구하려한다.

• Korean Journal of Microbiology
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• v.44 no.3
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• pp.193-198
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• 2008

ErmSF is one of the proteins which are produced by Streptomyces fradiae to avoid suicide by its autogenous macrolide antibiotic, tylosin and one of ERM proteins which are responsible for transferring the methyl group to $A_{2058}$ (Escherichia coli coordinate) in 23S rRNA, which reduces the affinity of MLS (macrolide-lincosamide-streptogramin B) antibiotics to 23S rRNA, thereby confers the antibiotic resistance on microorganisms ranging from antibiotic producers to pathogens. ErmSF contains an extra N-terminal end region (NTER), which is unique to ErmSF and 25% of amino acids of which is arginine known well to interact with RNA. Noticeably, arginine is concentrated in $^{58}RARR^{61}$ and functional role of each arginine in this motif was investigated through deletion and site-directed mutagenesis and the activity of mutant proteins in cell R60 and R61 was found to play an important role in enzyme activity through the study with deletion mutant up to R60 and R61. With the site-directed mutagenesis using deletion mutant of 1 to 59 (R60A, R61A, and RR60, 61AA), R60 was found more important than R61 but R61 was necessary for the proper activity of R60 and vice versa. And these amino acids were presumed to assume a secondary structure of $\alpha$-helix.

• Animal cells and systems
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• v.16 no.4
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• pp.289-294
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• 2012

Histone methylation has diverse functions including transcriptional regulation via its lysine or arginine residue methylation. Studies indicate that deregulation of histone methylation is linked to human cancers including leukemia. Histone H3K27 methyltrnasferase response element II binding protein (RE-IIBP), as a transcriptional repressor to target gene IL-5, interacts with HDAC and is over-expressed in leukemia patient samples. In this study, we have identified that hematopoiesis-related genes GATA1 and HOXA9 are down-regulated by RE-IIBP in K562 and 293T cells. Transient reporter analysis revealed that GATA1 transcription was repressed by RE-IIBP. On the other hand, HOXA9 and PBX-related homeobox gene MEIS1 was up-regulated by RE-IIBP. These results suggest that RE-IIBP might have a role in hematopoiesis or leukemogenesis by regulating the transcription of target genes, possibly via its H3K27 methyltransferase activity.

• BMB Reports
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• v.52 no.10
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• pp.601-606
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• 2019

Arginine methylation plays crucial roles in many cellular functions including signal transduction, RNA transcription, and regulation of gene expression. Protein arginine methyltransferase 8 (PRMT8), a unique brain-specific protein, is localized to the plasma membrane. However, the detailed molecular mechanisms underlying PRMT8 plasma membrane targeting remain unclear. Here, we demonstrate that the N-terminal 20 amino acids of PRMT8 are sufficient for plasma membrane localization and that oligomerization enhances membrane localization. The basic amino acids, combined with myristoylation within the N-terminal 20 amino acids of PRMT8, are critical for plasma membrane targeting. We also found that substituting Gly-2 with Ala [PRMT8(G2A)] or Cys-9 with Ser [PRMT8(C9S)] induces the formation of punctate structures in the cytosol or patch-like plasma membrane localization, respectively. Impairment of PRMT8 oligomerization/dimerization by C-terminal deletion induces PRMT8 mis-localization to the mitochondria, prevents the formation of punctate structures by PRMT8(G2A), and inhibits PRMT8(C9S) patch-like plasma membrane localization. Overall, these results suggest that oligomerization/dimerization plays several roles in inducing the efficient and specific plasma membrane localization of PRMT8.

• Korean Journal of Microbiology
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• v.49 no.2
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• pp.105-111
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• 2013

The Erm family of adenine-$N^6$ methyltransferases (MTases) is responsible for the development of resistance to macrolide-lincosamide-streptogramin B antibiotics through the methylation of 23S ribosomal RNA. Recently, it has been proposed that well conserved amino acids in ErnC' located in concave cleft between N-terminal 'catalytic' domain and C-terminal 'RNA-binding' domain interacts with substrate RNA. We carried out the site-directed mutagenesis and studied the function of the ErmSF R237 mutant in vitro and in vivo. R237 amino acid residue is located in the concave cleft between two domains. Furthermore this residue is very highly conserved in almost all the Erm family. Purified mutant protein exhibited only 51% enzyme activity compared to wild-type. Escherichia coli with R237A mutant protein compared to the wild-type protein expressing E. coli did not show any difference in its MIC (minimal inhibitory concentration) suggesting that even with lowered enzyme activity, mutant protein was able to efficiently methylate 23S rRNA to confer the resistance on E. coli expressing this protein. But this observation strongly suggests that R237 of ErmSF probably interacts with substrate RNA affecting enzyme activity significantly.

• 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.

• Korean Journal of Microbiology
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• v.47 no.3
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• pp.200-208
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• 2011

Most problematic antibiotic resistance mechanism for MLS (macrolide-lincosamide-streptogramn B) antibiotics encountered in clinical practice is mono- or dimethylation of specific adenine residue at 2058 (E. coli coordinate) of 23S rRNA which is performed by Erm (erythromycin ribosome resistance) protein through which bacterial ribosomes reduce the affinity to the antibiotics and become resistant to them. ErmSF is one of the four gene products produced by Streptomyces fradiae to be resistant to its own antibiotic, tylosin. Unlike other Erm proteins, ErmSF harbors idiosyncratic long N-terminal end region (NTER) 25% of which is comprised of arginine well known to interact with RNA. Furthermore, NTER was found to be important because when it was truncated, most of the enzyme activity was lost. Based on these facts, capability of NTER peptide to inhibit the enzymatic activity of ErmSF was sought. For this, expression system for two different proteins to be expressed in one cell was developed. In this system, two plasmids, pET23b and pACYC184 have unique replication origins to be compatible with each other in a cell. And expression system harboring promoter, ribosome binding site and transcription termination signal is identical but disparate amount of protein could be expressed according to the copy number of each vector, 15 for pACYC and 40 for pET23b. Expression of NTER peptide in pET23b together with ErmSF in pACYC 184 in E. coli successfully gave more amounts of NTER than ErmSF but no inhibitory effects were observed suggesting that there should be dynamicity in interaction between ErmSF and rRNA rather than simple and fixed binding to each other in methylation of 23S rRNA by ErmSF.