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Characterization of a Methyl Jasmonate Specific Esterase in Arabidopsis
Koo, Yeon Jong,Yoon, Eun Sil,Seo, Jun Sung,Kim, Ju-Kon,Choi, Yang Do The Korean Society for Applied Biological Chemistr 2013 Applied Biological Chemistry (Appl Biol Chem) Vol.56 No.1
Methyl jasmonate (MeJA)-specific methyl esterase of Arabidopsis (AtMJE) was identified and characterized. AtMJE has high substrate specificity to MeJA compared to other related substrates, methyl indole-3-acetate (MeIAA) and methyl salicylate (MeSA). Through enzyme kinetics analysis, we found AtMJE has similar level of substrate affinity to JA carboxyl methyltransferase (AtJMT). However, AtMJE has 10 times lower catalytic efficiency than AtJMT at low substrate concentrations. AtMJE gene expression was suppressed for 2 h after MeJA treatment, even though its expression recovered and was induced to maximum level within 8 h after treatment. AtMJE overexpressing plants (AtMJEox) showed enhanced MeJA methyl esterase activity demonstrating esterase activity of AtMJE in vivo. AtMJEox plants responded differentially to JA and MeJA in root growth. MeJA in the media could be a source for more JA production in AtMJEox plants, which resulted in root growth inhibition. In contrast, AtMJEox plants grown on JA containing media showed similar root growth inhibition as wild-type. These results show that AtMJE functions in altering JA/MeJA ratios in Arabidopsis and increased JA, because the conversion of MeJA to JA enhances JA responsive gene expression.
Song, Jong Tae,Koo, Yeon Jong,Park, Jong-Beum,Seo, Yean Joo,Cho, Yeon-Jeong,Seo, Hak Soo,Choi, Yang Do Springer-Verlag 2009 Molecules and cells Vol.28 No.2
<P>We reported previously that overexpression of a salicylic acid (SA) methyltransferase1 gene from rice (OsBSMT1) or a SA glucosyltransferase1 gene from Arabidopsis thaliana (AtSAGT1) leads to increased susceptibility to Pseudomonas syringae due to reduced SA levels. To further examine their roles in the defense responses, we assayed the transcript levels of AtBSMT1 or AtSAGT1 in plants with altered levels of SA and/or other defense components. These data showed that AtSAGT1 expression is regulated partially by SA, or non-expressor of pathogenesis related protein1, whereas AtBSMT1 expression was induced in SA-deficient mutant plants. In addition, we produced the transgenic Arabidopsis plants with RNAi-mediated inhibition of AtSAGT1 and isolated a null mutant of AtBSMT1 and then analyzed their phenotypes. A T-DNA insertion mutation in the AtBSMT1 resulted in reduced methyl salicylate (MeSA) levels upon P. syringae infection. However, accumulation of SA and glucosyl SA was similar in both the atbsmt1 and wild-type plants, indicating the presence of another SA methyltransferase or an alternative pathway for MeSA production. The AtSAGT1-RNAi line exhibited no altered phenotypes upon pathogen infection, compared to wild-type plants, suggesting that (an)other SA glucosyltransferase(s) in Arabidopsis plants may be important for the pathogenesis of P. syringae.</P>
(Yang Do Choi,(Jong Joo Cheong,(Ing Yu Hwang,(Jong Seob Lee,(Sang Ik Song,(Min Kyun Kim,(Song Yion Yeu,(Choon Kyun Jung,(Yeon Jong Koo,(Jong Tae Song,(Hak Soo Seo 한국응용생명화학회 2001 Journal of Applied Biological Chemistry (J. Appl. Vol.44 No.3
NTR1 gene of Brassica campestris L.ssp.perkinensis encodes a floral nectary-specific methyltransferase. In this study, the NTRl cDNA was expressed in E. coli to examine the enzymatic characteristics of the protein product. The GST-NTR1 fusion protein was p
Floral Nectary-specific Gene NTR1 Encodes a Jasmonic Acid Carboxyl Methyltransferase
Seo, Hak Soo,Song, Jong Tae,Koo, Yeon Jong,Jung, Choonkyun,Yeu, Song Yion,Kim, Minkyun,Song, Sang Ik,Lee, Jong Seob,Hwang, Ingyu,Cheong, Jong-Joo,Choi, Yang Do 한국응용생명화학회 2001 Journal of Applied Biological Chemistry (J. Appl. Vol.44 No.3
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.
Effects of Levetiracetam Monotherapy on the Cognitive Function of Epilepsy Patients
Koo, Dae Lim,Hwang, Kyoung Jin,Kim, Daeyoung,Kim, You-Jin,Kim, Ji Young,Shin, Wonchul,Kim, Mi Rim,Joo, Eun Yeon,Lee, Jong-Min,Hong, Seung Bong S. Karger AG 2013 European neurology Vol.70 No.1
<P>Abstract</P><P><B><I>Aims:</I></B> To estimate the effect of levetiracetam (LEV) on cognitive function and mood status in newly diagnosed epilepsy patients. <B><I>Methods:</I></B> Fifty-five drug-naïve epilepsy patients (M:F ratio = 31:24; mean age = 30.9 years) were included. All patients underwent two neuropsychological (NP) tests, one before receiving LEV and then another 12.9 ± 5.0 months after starting LEV monotherapy. We evaluated general cognitive function, verbal/visual attention and memory, linguistic and visuospatial functions, frontal lobe function, and mood status. Repeated-measures regression and generalized estimating equation models were applied to assess the effects of all the confounding variables such as seizure control, average LEV dose, duration of epilepsy, inter-test interval, and subtype of epilepsy syndrome. <B><I>Results:</I></B> LEV monotherapy over 1 year revealed significant improvements in the following domains of NP tests with the correction of possible confounding variables: verbal and visual attention, psychomotor speed, mental flexibility, executive function, verbal fluency and word generation. No NP domains showed any significant decrease. <B><I>Conclusion:</I></B> Our study suggested that LEV monotherapy had no harmful effect on cognitive function in drug-naïve patients with epilepsy.</P><P>Copyright © 2013 S. Karger AG, Basel</P>