Functional characterization of HigBA toxin-antitoxin system in an Arctic bacterium, Bosea sp. PAMC 26642

Eunsil Choi,Ahhyun Huh,Changmin Oh,오정일,강호영,황지환 한국미생물학회 2022 The journal of microbiology Vol.60 No.2

Toxin-antitoxin (TA) systems are growth-controlling genetic elements consisting of an intracellular toxin protein and its cognate antitoxin. TA systems have been spread among microbial genomes through horizontal gene transfer and are now prevalent in most bacterial and archaeal genomes. Under normal growth conditions, antitoxins tightly counteract the activity of the toxins. Upon stresses, antitoxins are inactivated, releasing activated toxins, which induce growth arrest or cell death. In this study, among nine functional TA modules in Bosea sp. PAMC 26642 living in Arctic lichen, we investigated the functionality of BoHigBA2. BohigBA2 is located close to a genomic island and adjacent to flagellar gene clusters. The expression of BohigB2 induced the inhibition of E. coli growth at 37°C, which was more manifest at 18°C, and this growth defect was reversed when BohigA2 was co-expressed, suggesting that this BoHigBA2 module might be an active TA module in Bosea sp. PAMC 26642. Live/dead staining and viable count analyses revealed that the BoHigB2 toxin had a bactericidal effect, causing cell death. Furthermore, we demonstrated that BoHigB2 possessed mRNA-specific ribonuclease activity on various mRNAs and cleaved only mRNAs being translated, which might impede overall translation and consequently lead to cell death. Our study provides the insight to understand the cold adaptation of Bosea sp. PAMC 26642 living in the Arctic.

Statistical methods used in articles published by the Journal of Periodontal and Implant Science

Choi, Eunsil,Lyu, Jiyoung,Park, Jinyoung,Kim, Hae-Young Korean Academy of Periodontology 2014 Journal of Periodontal & Implant Science Vol.44 No.6

Purpose: The purposes of this study were to assess the trend of use of statistical methods including parametric and nonparametric methods and to evaluate the use of complex statistical methodology in recent periodontal studies. Methods: This study analyzed 123 articles published in the Journal of Periodontal & Implant Science (JPIS) between 2010 and 2014. Frequencies and percentages were calculated according to the number of statistical methods used, the type of statistical method applied, and the type of statistical software used. Results: Most of the published articles considered (64.4%) used statistical methods. Since 2011, the percentage of JPIS articles using statistics has increased. On the basis of multiple counting, we found that the percentage of studies in JPIS using parametric methods was 61.1%. Further, complex statistical methods were applied in only 6 of the published studies (5.0%), and nonparametric statistical methods were applied in 77 of the published studies (38.9% of a total of 198 studies considered). Conclusions: We found an increasing trend towards the application of statistical methods and nonparametric methods in recent periodontal studies and thus, concluded that increased use of complex statistical methodology might be preferred by the researchers in the fields of study covered by JPIS.

The GTPase BipA expressed at low temperature in <i>Escherichia coli</i> assists ribosome assembly and has chaperone-like activity

Choi, Eunsil,Hwang, Jihwan American Society for Biochemistry and Molecular Bi 2018 The Journal of biological chemistry Vol.293 No.47

<P>BPI-inducible protein A (BipA) is a conserved ribosome-associated GTPase in bacteria that is structurally similar to other GTPases associated with protein translation, including IF2, EF-Tu, and EF-G. Its binding site on the ribosome appears to overlap those of these translational GTPases. Mutations in the <I>bipA</I> gene cause a variety of phenotypes, including cold and antibiotics sensitivities and decreased pathogenicity, implying that BipA may participate in diverse cellular processes by regulating translation. According to recent studies, a <I>bipA</I>-deletion strain of <I>Escherichia coli</I> displays a ribosome assembly defect at low temperature, suggesting that BipA might be involved in ribosome assembly. To further investigate BipA's role in ribosome biogenesis, here, we compared and analyzed the ribosomal protein compositions of MG1655 WT and <I>bipA</I>-deletion strains at 20 °C. Aberrant 50S ribosomal subunits (<I>i.e.</I> 44S particles) accumulated in the <I>bipA</I>-deletion strain at 20 °C, and the ribosomal protein L6 was absent in these 44S particles. Furthermore, <I>bipA</I> expression was significantly stimulated at 20 °C, suggesting that it encodes a cold shock–inducible GTPase. Moreover, the transcriptional regulator cAMP receptor protein (CRP) positively promoted <I>bipA</I> expression only at 20 °C. Importantly, GFP and α-glucosidase refolding assays revealed that BipA has chaperone activity. Our findings indicate that BipA is a cold shock–inducible GTPase that participates in 50S ribosomal subunit assembly by incorporating the L6 ribosomal protein into the 44S particle during the assembly.</P>

Heterologous Expression of Der Homologs in an <i>Escherichia coli der</i> Mutant and Their Functional Complementation

Choi, Eunsil,Kang, Nalae,Jeon, Young,Pai, Hyun-Sook,Kim, Sung-Gun,Hwang, Jihwan American Society for Microbiology 2016 Journal of Bacteriology Vol.198 No.17

<P>The unique Escherichia coli GTPase Der (double Era-like GTPase), which contains tandemly repeated GTP-binding domains, has been shown to play an essential role in 50S ribosomal subunit biogenesis. The depletion of Der results in the accumulation of precursors of 50S ribosomal subunits that are structurally unstable at low Mg2+ concentrations. Der homologs are ubiquitously found in eubacteria. Conversely, very few are conserved in eukaryotes, and none is conserved in archaea. In the present study, to verify their conserved role in bacterial 50S ribosomal subunit biogenesis, we cloned Der homologs from two gammaproteobacteria, Klebsiella pneumoniae and Salmonella enterica serovar Typhimurium; two pathogenic bacteria, Staphylococcus aureus and Neisseria gonorrhoeae; and the extremophile Deinococcus radiodurans and then evaluated whether they could functionally complement the E. coli der-null phenotype. Only K. pneumoniae and S. Typhimurium Der proteins enabled the E. coli der-null strain to grow under nonpermissive conditions. Sucrose density gradient experiments revealed that the expression of K. pneumoniae and S. Typhimurium Der proteins rescued the structural instability of 50S ribosomal subunits, which was caused by E. coli Der depletion. To determine what allows their complementation, we constructed Der chimeras. We found that only Der chimeras harboring both the linker and long C-terminal regions could reverse the growth defects of the der-null strain. Our findings suggest that ubiquitously conserved essential GTPase Der is involved in 50S ribosomal subunit biosynthesis in various bacteria and that the linker and C-terminal regions may participate in species-specific recognition or interaction with the 50S ribosomal subunit. IMPORTANCE In Escherichia coli, Der (double Era-like GTPase) is an essential GTPase that is important for the production of mature 50S ribosomal subunits. However, to date, its precise role in ribosome biogenesis has not been clarified. In this study, we used five Der homologs from gammaproteobacteria, pathogenic bacteria, and an extremophile to elucidate their conserved function in 50S ribosomal subunit biogenesis. Among them, Klebsiella pneumoniae and Salmonella enterica serovar Typhimurium Der homologs implicated the participation of Der in ribosome assembly in E. coli. Our results show that the linker and C-terminal regions of Der homologs are correlated with its functional complementation in E. coli der mutants, suggesting that they are involved in species-specific recognition or interaction with 50S ribosomal subunits.</P>

Competence for In-house English Editors:

Choi. Eunsil,Kim. Dohun 한국통번역교육학회 2016 통번역교육연구 Vol.14 No.2

With the rise of interpreting and translation training, an increasing number of graduates are entering the job market. Many of them seek English editor positions in the government, the largest employer of interpreters and translators. However, there are few studies that deal with the concrete competences required of English editors. In order to fill the research gap, this study first reviews existing studies that deal with interpreting and translation competence, followed by a thorough corpus-analysis of job postings that seek English editors―qualifications and job descriptions on the job postings are collected, and the most frequently-appearing phrases are listed for analysis. The findings strongly imply that the ecosystem of the job has significantly changed. Today’s English editors need much more than interpreting and translation competence; they are expected to work as international relations personnel whose work involves drafting up documents, organizing international conferences, and so forth. Interpreting and translator training institutions should also recognize the altered landscape and incorporate the competences into their curricula.

부모의 심리적 통제가 청소년의 스트레스 반응에 미치는 영향: 마음챙김과 정서조절곤란의 순차적 매개효과

최은실(Eunsil Choi),이우경(Woo Kyeong Lee) 한국발달지원학회 2022 발달지원연구 Vol.11 No.3

본 연구는 중학생을 대상으로 부모의 심리적 통제와 스트레스 반응 간의 관계를 마음챙김과 정서조절곤란의 순차적 매개효과에 대해 확인하는 것이다. 이를 위해, 중학생 308명(남자: 150명, 여자: 158명)을 대상으로 부모의 심리적 통제 개정판(PCDS), 청소년용 일상적 스트레스 반응 척도, 한국판 정서조절곤란 척도(K-DERS), 한국판 아동 및 청소년 마음챙김 척도(K-CAMM)를 사용하여, 부모의 심리적 통제, 스트레스반응, 정서조절곤란, 마음챙김을 각각 측정하였다. 분석방법으로는 SPSS와 AMOS를 이용한 기술통계분석, 상관분석, 신뢰도분석, 구조방정식 모형검증을 통한 매개효과를 확인하였고, 매개효과의 통계적 유의성 검증을 위해 부트스트래핑 방법을 사용하였다. 결과를 종합하면, 부모의 심리적 통제와 스트레스 반응 간의 관계를 마음챙김과 정서조절곤란이 순차적으로 매개하는 것으로 나타났다. 따라서 부모의 심리적인 통제는 마음챙김을 어렴게 하고 정서조절곤란을 증가시켜 최종적으로 스트레스 반응을 증가시킬 가능성이 시사되었다. 이러한 연구 결과를 바탕으로 본 연구의 의의 및 제한점과 후속연구를 위한 제언을 논의하였다. The purpose of this study was to examine the parental psychological control, mindfulness, and difficulties in emotion regulation on middle school students’ stress response. It also measured the mediating effect of mindfulness and difficulties in emotion regulation on young adolescent’s stress response. The participants were 308 middle school students attending middle schools in South Korea. Self-report questionnaires were developed to measure the students’ stress response, and they were administered along with parental psychological control-disrespect scale(PCDS), daily stress response inventory, the Korean version of child and adolescent mindfulness measure(K-CAMM) and the Korean version of the difficulties in emotion regulation scale(K-DERS). In order to verify the mediating effects, descriptive statistical analysis, correlation analysis, and a structural equations verification model were used through SPSS and AMOS, and the bootstrapping method was used to verify the statistical significant of mediating effects. The results of this study could be summarized as follows. First, parental psychological control, mindfulness, difficulties in emotion regulation and stress response had statistically significant correlations. Second, fromthe relationship between parental psychological control and young adolescents’ stress response, mindfulness and difficulties in emotion regulation were found to have sequential mediating effects. As the participants perceived that they possessed high psychological control, mindfulness decreased, and as mindfulness decreased, difficulties in emotion regulation increased, increasing stress response. Finally, the limitations if this study and future research directions are suggested.

Escherichia coli 에서 리보솜 조립과정에 관여하는 단백질들

최은실(Eunsil Choi),황지환(Jihwan Hwang) 한국생명과학회 2014 생명과학회지 Vol.24 No.8

리보솜은 mRNA상의 유전정보를 단백질로 번역하는 세포에 필수적인 거대복합체이다. 이러한 리보솜은 리보핵산단백질 복합체로, rRNA와 리보솜 단백질로 이루어져있다. 리보솜 조립과정은 리보솜 단백질 이외에도 많은 조립인자들이 각 구성요소의 조립을 도움으로써 이루어진다. 세포 내 리보솜 조립과정에 참여하는 조립인자들로 GTPase, ATPase, 샤페론, RNA helicase, 수식효소 등 다양한 단백질들이 알려졌다. 리보솜 조립과정 중 이러한 조립인자들은 리보솜 단백질 또는 rRNA의 수식에 참여하거나, 리보솜 단백질들과 rRNA의 조립 등을 돕는다. 이러한 리보솜 조립인자들에 관한 유전학적, 구조적, 생화학적 실험결과들이 많이 존재하지만 정확한 리보솜 조립과정과 이러한 조립인자들의 역할에 대해서는 아직 밝혀지지 않았다. 현재까지의 연구결과를 바탕으로 E. coli의 리보솜 조립과정을 돕는 단백질들에 대하여 알아보고자 한다. The ribosome is a protein synthesizing machinery and a ribonucleoprotein complex that consists of three ribosomal RNAs (23S, 16S and 5S) and 54 ribosomal proteins in bacteria. In the course of ribosome assembly, ribosomal proteins (r-protein) and rRNAs are modified, the r-proteins bind to rRNAs to form ribonucleoprotein complexes which are folded into mature ribosomal subunits. In this process, a number of non-ribosomal trans-acting factors organize the assembly process of the components. Those factors include GTP- and ATP-binding proteins, rRNA and r-protein modification enzymes, chaperones, and RNA helicases. During ribosome biogenesis, they participate in the modifications of ribosomal proteins and RNAs, and the assemblies of ribosomal proteins with rRNAs. Ribosomes can be assembled from a discrete set of components in vitro, and it is notable that in vivo ribosome assembly is much faster than in vitro ribosome assembly. This suggests that non-ribosomal ribosome assembly factors help to overcome several kinetic traps in ribosome biogenesis process. In spite of accumulation of genetic, structural, and biochemical data, not only the entire procedure of bacterial ribosome synthesis but also most of roles of ribosome assembly factors remain elusive. Here, we review ribosome assembly factors involved in the ribosome maturation of Escherichia coli, and summarize the contributions of several ribosome assembly factors which associate with 50S and 30S ribosomal subunits, respectively.

통역 훈련용 플랫폼 개발을 위한 기초 연구

최은실(Eunsil Choi) 한국통번역교육학회 2023 통번역교육연구 Vol.21 No.4

직류 전원과 펄스 전원을 이용하여 오염된 토양에서의 중금속과 페놀 처리

최창식 ( Changsik Choi ),홍범의 ( Bumeui Hong ),최희영 ( Hee Young Choi ),이은실 ( Eunsil Lee ),최석순 ( Suk Soon Choi ) 한국공업화학회 2016 공업화학 Vol.27 No.6

본 연구에서는 오염된 토양 속에 함유된 중금속과 페놀의 처리에 대하여 직류 전원과 펄스 전원을 적용하여 고찰하였다. 직류 전원을 사용하여 오염된 토양을 처리하였을 때 구리, 아연, 비소, 납의 제거 효율은 각각 70, 87, 12, 11%를 나타내었고, 페놀은 85% 이상이 제거되었다. 그리고 펄스 전원을 사용하였을 때 구리, 아연, 비소, 납의 제거효율이 각각 87, 91, 37, 38%이었으며, 페놀은 88% 제거되었다. 이러한 결과들은 펄스 전원을 오염된 토양에 적용하였을 때, 전기삼투 현상은 낮아졌지만 중금속들의 전류이동 속도가 증가함을 알 수 있었다. 또한 토양의 점토 성분에 의한 흡착 능력의 향상으로 인하여 비소와 납의 제거효율이 증가되었다. 따라서 이러한 직류 전원과 펄스 전원을 이용하는 동전기 실험 결과들은 여러 가지 중금속들과 페놀을 처리하는 복원 기술로 유용하게 활용될 수 있을 것이다. In this work, the treatment of heavy metals and phenol in the contaminated soil was investigated by applying direct current (DC) and pulse voltage. When the DC was used, the removal efficiencies for Cu, Zn, As, and Pb were 73, 88, 10, and 10%, respectively, and more than 95% for phenol was removed. Furthermore, when a pulse voltage was employed the removal efficiencies for Cu, Zn, As, and Pb were 88, 92, 40, and 40%, respectively, and 87% of phenol was removed. The results indicate that the application of a pulse voltage for the treatment of contaminated soil reduced electro-osmosis, but increased the rate of electric current movement of heavy metals. In addition, the removal efficiencies for As and Pb have been improved due to the enhanced adsorption capacity of clay components in the soil. Therefore, these experimental results could be effect-tively applied in remediation technology for the treatment of various heavy metals and phenol.

Intrahepatic Cholangiocarcinoma in Patients with Cirrhosis: Differentiation from Hepatocellular Carcinoma by Using Gadoxetic Acid—enhanced MR Imaging and Dynamic CT

Choi, Sang Hyun,Lee, Seung Soo,Kim, So Yeon,Park, So Hyun,Park, Seong Ho,Kim, Kang Mo,Hong, Seung-Mo,Yu, Eunsil,Lee, Moon-Gyu RADIOLOGICAL SOCIETY OF NORTH AMERICA 2017 Radiology Vol.282 No.3

<P>Conclusion: The use of PVP washout instead of conventional washout at gadoxetic acid-enhanced MR imaging prevents the mis-classification of IHCC as HCC in a cirrhotic liver but leads to a decreased sensitivity for HCC.</P>