• BMB Reports
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• v.51 no.12
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• pp.609-610
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• 2018

Glycosylation is one form of protein modification and plays a key role in protein stability, function, signaling regulation and even cancer. NleB and SseK are bacterial effector proteins and possess glycosyltransferase activity, even though they have different substrate preferences. NleB/SseKs transfer the GlcNAc sugar to an arginine residue of host proteins, leading to reduced $NF-{\kappa}B-dependent$ responses. By combining X-ray crystallography, NMR, molecular dynamics, enzyme kinetic assays and in vivo experiments, we demonstrated that a conserved HEN (His-Glu-Asn) motif in the active site plays a key role in enzyme catalysis and virulence. The lid-domain regulates the opening and closing of the active site and the HLH domain determines the substrate specificity. Our findings provide evidence for the enzymatic mechanism by which arginine can be glycosylated by SseK/NleB enzymes.

• Fisheries and Aquatic Sciences
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• v.26 no.3
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• pp.204-215
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• 2023

The thermolabile haemolysin (tlh) of Vibrio parahaemolyticus (Vptlh) from V. parahaemolyticus is a multiple-function enzyme, initially describes as a haemolytic factor activated by lecithin and phospholipase A2 enzymatic activity (Shinoda, 1991; Vazquez-Morado, 2021; Yanagase et al., 1970). Until now, the tlh structure has hypothesized including N-terminal and C-terminal domain, but what domain of the Vptlh structure does the haemolytic activity has not been refined yet. In this study, a 450-bp VpTLH nucleotide sequence of the entire Vptlh gene encoded the C-terminal domain cloned firstly to examine its responsibility in the activity of the Vptlh. The C-terminal domain fused with a 6-His-tag named the His-tag-VpC-terminal domain was expressed successfully in soluble form in the BL21 (DE3) PlysS cell. Remarkably, both expression and purification results confirmed a high agreement in the molecular weight of the His-tag-VpC-terminal domain was 47 kDa. This work showed the His-tag-VpC-terminal domain lysed the erythrocyte membranes in the blood agar and the phosphate buffered saline (0.9%) media without adding the lecithin substrate of the phospholipase enzyme. Haemolysis occurred at all tested diluted concentrations of His-tag-VpC-terminal domain (p < 0.05), providing evidence for the independent haemolytic activity of the His-tag-VpC-terminal domain. The content of 100 ㎍ of the His-tag-VpC-terminal domain brought the highest haemolytic activity of 80% compared to that in the three remaining contents. Significantly, the His-tag-VpC-terminal domain demonstrated not to involve the phospholipase activity in Luria-Bertani agar supplemented with 1% (vol/vol) egg yolk emulsion. All results proved the vital responsibility of the His-tag-VpC-terminal domain in causing the haemolytic activity without the required activation by the phospholipase enzyme. Raw extracts of Phellinus igniarus and Phellinus pipi at 10^-1 mg/mL inhibited the haemolytic activity of the His-tag-VpC-terminal domain from 67.7% to 87.42%, respectively. Hence applying the His-tag-VpC-terminal domain as a simple biological material to evaluate quickly potential derivatives against the Vptlh in vivo conditions will accessible and more advantageous than using the whole of the Vptlh.

• Journal of Microbiology and Biotechnology
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• v.8 no.2
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• pp.152-157
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• 1998

To analyze the role of the C and D domains in the cyclization activity of cyclodextrin glucanotransferase (CGTase), two plasmids, pKB1ΔC300 and pKB1ΔD96, were constructed in which DNA regions encoding 100 and 32 amino acids, respectively, from the C and D domains of B. stearothermophilus NO2 CGTase were deleted. The mutated CGTase from the pKBlΔC300 produced much lower amounts of ${\alpha}$-, ${\beta}$-, and $\gamma$-cyclodextrin (CD) than the parental CGTase. However, the mutated CGTase from the pKBlΔD96 showed a similar production pattern of CDs to wild-type CGTase. The production ratios of the ${\alpha}$-, ${\beta}$- and $\gamma$-CDs were not affected by the deletions, when compared to those of parental CGTase. The optimum temperature of the mutated CGTase from the pKBlΔC300 was decreased from $60^{\circ}C$ to $55^{\circ}C$. The optimum pH of the mutated CGTase from the pKB1D96 was shifted from 6.0 to 7.0. The thermostability of the two mutant CGTases were not changed. From these results, it is suggested that the C and D domains are not related to cyclization activity directly because mutant-enzymes deleted C or D domains still possessed their activity. However, they are important for other enzymatic properties such as productivity and pH optimum as a partition of CGTase tertiary structure.

• Toxicological Research
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• v.12 no.2
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• pp.155-161
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• 1996

The enzymatic properties for NADPH-P450 reductase domain of a fusion protein between human cytochrome P450 1A1 and rat NADPH-P450 reductase expressed in Escherichia coli were investigated. The fusion plasmid pCW/1A1OR-expressed E. coli membrane showed high NADPH-cytochrome c reductase activity ($830.1\pm 85.8 nmol\cdot min^{-1}\cdot mg protein^{-1}$), while pCW control vector and P 450 1A1 expression vector pCW/1A1 showed relatively quite low activity ($4.35\pm 0.49, 3.27\pm 0.50 nmol\cdot min^{-1}\cdot mg protein^{-1}$, respectively). The kinetic curves for NADPH-cytochrome c reductase followed typical Michaelis-Menten kinetics. The $K_{max}$ and $V_{max}$ for NADPH-dependent reductase activity were $8.24\pm 2.61\mu $and $817.9\pm 60.8 nmol\cdot min^{-1}\cdot mg protein^{-1}$, respectively, whereas those for cytochrome c-dependent reductase activity were $19.97\pm 2.86\mu M$ and $1303.5\pm 67.1 nmol\cdot min^{-1}\cdot mg protein^{-1}$. The reductase activities were also compared with those of rat, porcine and human liver microsomes. The activity of pCW/ 1A1OR-expressed E. coli membrane was 15.2-fold higher than that of rat liver microsome. Treatment with benzo(a)pyrene, 7-ethoxyresorufin and $\alpha$-naphthofiavone which are known as specific substrates or inhibitor for human P450 1A1 increased NADPH-cytochrome c reductase activity of fusion protein in E. coli membrane dose-dependently. These results demonstrate that the membrane topology of fused enzyme may be important for activity of its NADPH-P450 reductase domain.

• BMB Reports
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• v.50 no.2
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• pp.85-90
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• 2017

Recently, we demonstrated that superoxide dismutase 3 (SOD3) is a strong candidate for biomedicine. Anti-oxidant function of SOD3 was accomplished without cell penetration, and it inhibited the inflammatory responses via non-enzymatic functions. SOD3 has the heparin binding domain associating cell surface. Interestingly, we found that $Zn^{2+}$ promotes transduction effects of recombinant human SOD3 (rhSOD3) by increasing uptake via the heparin binding domain (HBD). We demonstrated an uptake of rhSOD3 from media to cell lysate via HBD, resulting in an accumulation of rhSOD3 in the nucleus, which was promoted by the presence of $Zn^{2+}$. This resulted in increased inhibitory effects of rhSOD3 on NF-{\kappa}B and STAT3 signals in the presence of $Zn^{2+}$, which shows elevated association of rhSOD3 into the cells. These results suggest that an optimized procedure can help to enhance the inflammatory efficacy of rhSOD3, as a novel biomedicine.

• BMB Reports
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• v.38 no.6
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• pp.633-638
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• 2005

Biosynthesis of prostanoids is regulated by three sequential enzymatic steps, namely phospholipase $A_2$ enzymes, cyclooxygenase (COX) enzymes, and various lineage-specific terminal prostanoid synthases. Prostaglandin E synthase (PGES), which isomerizes COX-derived $PGH_2$ specifically to $PGE_2$, occurs in multiple forms with distinct enzymatic properties, expressions, localizations and functions. Two of them are membrane-bound enzymes and have been designated as mPGES-1 and mPGES-2. mPGES-1 is a perinuclear protein that is markedly induced by proinflammatory stimuli, is down-regulated by anti inflammatory glucocorticoids, and is functionally coupled with COX-2 in marked preference to COX-1. Recent gene targeting studies of mPGES-1 have revealed that this enzyme represents a novel target for anti-inflammatory and anti-cancer drugs. mPGES-2 is synthesized as a Golgi membrane-associated protein, and the proteolytic removal of the N-terminal hydrophobic domain leads to the formation of a mature cytosolic enzyme. This enzyme is rather constitutively expressed in various cells and tissues and is functionally coupled with both COX-1 and COX-2. Cytosolic PGES (cPGES) is constitutively expressed in a wide variety of cells and is functionally linked to COX-1 to promote immediate $PGE_2$ production. This review highlights the latest understanding of the expression, regulation and functions of these three PGES enzymes.

• Molecules and Cells
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• v.37 no.7
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• pp.526-531
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• 2014

Human PARP family consists of 17 members of which PARP-1 is a prominent member and plays a key role in DNA repair pathways. It has an N-terminal DNA-binding domain (DBD) encompassing the nuclear localisation signal (NLS), central automodification domain and C-terminal catalytic domain. PARP-1 accounts for majority of poly-(ADP-ribose) polymer synthesis that upon binding to numerous proteins including PARP itself modulates their activity. Reduced PARP-1 activity in ageing human samples and its deficiency leading to telomere shortening has been reported. Hence for cell survival, maintenance of genomic integrity and longevity presence of intact PARP-1 in the nucleus is paramount. Although localisation of full-length and truncated PARP-1 in PARP-1 proficient cells is well documented, subcellular distribution of PARP-1 fragments in the absence of endogenous PARP-1 is not known. Here we report the differential localisation of PARP-1 Nterminal fragment encompassing NLS in PARP-$1^{+/+}$ and PARP-$1^{-/-}$ mouse embryo fibroblasts by live imaging of cells transiently expressing EGFP tagged fragment. In PARP-$1^{+/+}$ cells the fragment localises to the nuclei presenting a granular pattern. Furthermore, it is densely packaged in the midsections of the nucleus. In contrast, the fragment localises exclusively to the cytoplasm in PARP-$1^{-/-}$ cells. Flourescence intensity analysis further confirmed this observation indicating that the N-terminal fragment requires endogenous PARP-1 for its nuclear transport. Our study illustrates the trafficking role of PARP-1 independently of its enzymatic activity and highlights the possibility that full-length PARP-1 may play a key role in the nuclear transport of its siblings and other molecules.

• Biomedical Science Letters
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• v.12 no.4
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• pp.419-425
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• 2006

Phospholipase $C-{\gamma}1\;(PLC-{\gamma}1)$ is an important signaling molecule for cell proliferation and differentiation. $PLC-{\gamma}1$ contains two pleckstrin homology (PH) domains, which are responsible for protein-protein interaction and protein-lipid interaction. $PLC-{\gamma}1$ also has two Src homology (SH)2 domains and a SH3 domain, which are responsible for protein- protein interaction. To identity proteins that specifically binds to PH domain of $PLC-{\gamma}1$, we prepared and incubated the glutathione S-transferase(GST)-fused PH domains of $PLC-{\gamma}1$ with COS7 cell lysate. We found that 90 kDa protein specifically binds to PH domain of $PLC-{\gamma}1$. By matrix-assisted laser desorption ionization time of flight-mass spectrometry, the 90 kDa protein revealed to be heat shock protein (Hsp) $90{\beta}$. Hsp $90{\beta}$ is a molecular chaperone that stabilizes and facilitates the folding of proteins that are involved in cell signaling, including receptors for steroids hormones and a variety of protein kinases. To know whether Hsp $90{\beta}$ affects on $PLC-{\gamma}1$ activity, we performed $PIP_2$ hydrolyzing activity of $PLC-{\gamma}1$ in the presence of purified Hsp $90{\beta}$ in vitro. Our results show that the Hsp $90{\beta}$ dose-dependently inhibits the enzymatic activity of $PLC-{\gamma}1$ and further suggest that Hsp $90{\beta}$ regulates cell growth and differentiation via regulation of $PLC-{\gamma}1$ activity.

• Molecules and Cells
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• v.37 no.4
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• pp.322-329
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• 2014

N-acetylglucosamine kinase (GlcNAc kinase or NAGK; EC 2.7.1.59) is highly expressed and plays a critical role in the development of dendrites in brain neurons. In this study, the authors conducted structure-function analysis to verify the previously proposed 3D model structure of GlcNAc/ATP-bound NAGK. Three point NAGK mutants with different substrate binding capacities and reaction velocities were produced. Wild-type (WT) NAGK showed strong substrate preference for GlcNAc. Conversion of Cys143, which does not make direct hydrogen bonds with GlcNAc, to Ser (i.e., C143S) had the least affect on the enzymatic activity of NAGK. Conversion of Asn36, which plays a role in domain closure by making a hydrogen bond with GlcNAc, to Ala (i.e., N36A) mildly reduced NAGK enzyme activity. Conversion of Asp107, which makes hydrogen bonds with GlcNAc and would act as a proton acceptor during nucleophilic attack on the ${\gamma}$-phosphate of ATP, to Ala (i.e., D107A), caused a total loss in enzyme activity. The overexpression of EGFP-tagged WT or any of the mutant NAGKs in rat hippocampal neurons (DIV 5-9) increased dendritic architectural complexity. Finally, the overexpression of the small, but not of the large, domain of NAGK resulted in dendrite degeneration. Our data show the effect of structure on the functional aspects of NAGK, and in particular, that the small domain of NAGK, and not its NAGK kinase activity, plays a critical role in the upregulation of dendritogenesis.

• Proceedings of the SCSK Conference
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• 2003.09a
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• pp.630-644
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• 2003

A human Cu, Zn-superoxide dismutase (Cu, Zn-SOD) was fused with a Tat PTD of HIV-1 to produce a novel anti-aging ingredient, Tat-SOD for cosmeceuticals. Test of stability and evaluation of transduction efficacy and enzymatic activity suggest Tat-SOD is an effective active ingredient for anti-aging treatment.