• BMB Reports
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• 제32권3호
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• pp.215-225
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• 1999

Phytochromes (with gene family members phyA, B, C, D, and E) are a wavelength-dependent light sensor or switch for gene regulation that underscore a number of photo responsive developmental and morphogenic processes in plants. Recently, phytochrome-like pigment proteins have also been discovered in prokaryotes, possibly functioning as an auto-phosphorylating/phosphate-relaying two-component signaling system (Yeh et al., 1997). Phytochromes are photochromically convertible between the light sensing Pr and regulatory active Pfr forms. Red light converts Pr to Pfr, the latter having a "switch-on" conformation. The Pfr form triggers signal transduction pathways to the downstream responses including the expression of photosynthetic and other growth-regulating genes. The components involved in and the molecular mechanisms of the light signal transduction pathways are largely unknown, although G-proteins, protein kinases, and secondary messengers such as $Ca^{2+}$ ions and cGMP are implicated. The 124-127 kDa phytochromes form homodimeric structures. The N-terminal half contains the tetrapyrrolic phytochromobilin for red/far-red light absorption. The C-terminal half includes both a dimerization motif and regulatory box where the red light signal perceived by the chromophore-domain is recognized and transduced to initiate the signal transduction cascade. A working model for the inter-domain signal communication within the phytochrome molecule is proposed in this Review.

• 생명과학회지
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• 제24권12호
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• pp.1330-1338
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• 2014

결핵균인 Mycobacterium tuberculosis H37Rv에서는 16개의 adenylyl cyclase (AC) 유전자가, 비병원성인 M. smegmatis에서는 10개의 AC 유전자가 발견되었다. M. smegmatis에서 발견된 10개의 AC 유전자들 중 MSMEG_0228, MSMEG_3243, MSMEG_3780, MSMEG_4279, MSMEG_4477, MSMEG_6154 유전자들의 발현은 저산소 조건에서 유도되었다. 반면에 M. smegmatis가 nitric oxide (NO)에 노출이 되면 MSMEG_3780과 MSMEG_4279 유전자의 발현이 유도되었다. 유산소 조건에서 키운 M. smegmatis와 비교할 때, 저산소 조건에서 성장한 M. smegmatis 세포 내부와 성장 배지 내의 cAMP 양은 각각 450배와 9.8배 증가하였다. M. smegamtis가 NO에 노출이 되면 세포 내의 cAMP 농도는 5.8배 증가하였다. DevSR two-component system은 M. smegmatis가 저산소 조건이나 NO에 노출되었을 때 많은 유전자의 발현을 유도하는 주요 조절계로 알려져 있는데, 저산소 조건에서 발현이 유도된 6개의 AC 유전자의 발현이 M. smegmatis devR mutant에서도 wild type에서와 마찬가지로 저산소 조건에서 유도됨이 관찰되었다. 이 결과는 저산소 조건에서 발현이 유도되는 6개의 AC 유전자들이 DevSR two-component system에 의해 조절되지 않음을 나타내고 있다. 저산소 조건에서 발현이 가장 많이 유도된 MSMEG_3780 유전자의 발현조절에 관련이 있는 조절자를 발굴하기 위해 ligand fishing 분석을 수행하였고, 후보 조절자로서 MSMEG_5136을 발굴하였다.

• Nuclear Engineering and Technology
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• 제41권4호
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• pp.447-454
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• 2009

This paper is a technical review of the research and development results of the Korea Nuclear Instrumentation and Control System (KNICS) project and Nu-Tech 2012 program. In these projects man-machine interface system architecture, two digital platforms, and several control and protection systems were developed. One platform is a Programmable Logic Controller (PLC) for a digital safety system and another platform is a Distributed Control System (DCS) for a non-safety control system. With the safety-grade platform PLC, a reactor protection system, an engineered safety feature-component control system, and reactor core protection system were developed. A power control system was developed based on the DCS. A logic alarm cause tracking system was developed as a man-machine interface for APR1400. Also, Integrated Performance Validation Facility (IPVF) was developed for the evaluation of the function and performance of developed I&C systems. The safety-grade platform PLC and the digital safety system obtained approval for the topical report from the Korean regulatory body in February of 2009. A utility and vendor company will determine the suitability of the KNICS and Nu- Tech 2012 products to apply them to the planned nuclear power plants.

• 생명과학회지
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• 제16권3호
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• pp.485-492
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• 2006

광합성세균인 Rhodobacter sphaeroides의 PrrBA two-component system은 산소분압의 변화에 따라 광합성 유전자의 발현을 조절하는 주요한 조절계 중 하나이다. PrrBA two-component system은 PrrB histidine kinase와 PrrA response regulator로 구성되어 있는데, PrrB의 N-말단 transmembrane 도메인은 신호인지 도메인으로서, 여섯 개의 transmembrane helix가 세 개의 periplasmic loop와 두 개의 cytoplasmic loop을 형성하고 있다. 그 중 세 번째, 네 번째 transmembrane helix와 두 번째 periplasmic loop가 산화/환원 인지 기능에 있어 중요한 역할을 할 것이라고 제안되었다. 본 연구에서는, 두 번째 periplasmic loop와 그 인접 부위에서의 돌연변이 (Asp-90, Gln-93, Leu-94, Leu-98, Asn-106)에 의해 PrrB의 인지 기능에 있어 심각한 결함이 생기는 것을 증명하였고, 이는 이 아미노산들이 PrrB의 산화/환원 인지 기능에 연관되어 있을 수 있다는 것을 보여준다. PrrB의 돌연변이 형태 (D90E, D90N, D90A)가 대장균에서 과발현되어서 affinity chromatography에 의해 정제되었고, 정제된 단백질의 자가인산화 반응이 측정되었다. PrrB D90N 변이형태는 PrrB wild-type보다 높은 자가인산화 활성을 가지는 반면에, PrrB D90E 변이형태는 PrrB wild-type보다 낮은 자가인산화 활성을 나타내었다. 그리고 D90A 변이형태는 PrrB의 자가인산화 활성이 매우 약화되었다.

• Journal of Microbiology and Biotechnology
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• 제33권9호
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• pp.1130-1140
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• 2023

Among the AAA+ proteases in bacteria, FtsH is a membrane-bound ATP-dependent metalloprotease, which is known to degrade many membrane proteins as well as some cytoplasmic proteins. In the intracellular pathogen Salmonella enterica serovar Typhimurium, FtsH is responsible for the proteolysis of several proteins including MgtC virulence factor and MgtA/MgtB Mg²⁺ transporters, the transcription of which is controlled by the PhoP/PhoQ two-component regulatory system. Given that PhoP response regulator itself is a cytoplasmic protein and also degraded by the cytoplasmic ClpAP protease, it seems unlikely that FtsH affects PhoP protein levels. Here we report an unexpected role of the FtsH protease protecting PhoP proteolysis from cytoplasmic ClpAP protease. In FtsH-depleted condition, PhoP protein levels decrease by ClpAP proteolysis, lowering protein levels of PhoP-controlled genes. This suggests that FtsH is required for normal activation of PhoP transcription factor. FtsH does not degrade PhoP protein but directly binds to PhoP, thus sequestering PhoP from ClpAP-mediated proteolysis. FtsH's protective effect on PhoP can be overcome by providing excess ClpP. Because PhoP is required for Salmonella's survival inside macrophages and mouse virulence, these data implicate that FtsH's sequestration of PhoP from ClpAP-mediated proteolysis is a mechanism ensuring the amount of PhoP protein during Salmonella infection.

• Nuclear Engineering and Technology
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• 제37권2호
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• pp.139-150
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• 2005

A robust control design procedure for a nuclear reactor has been developed and experimentally validated on the Penn State TRIGA research reactor. The utilization of the robust controller as a component of an autonomous control system is also demonstrated. Two methods of specifying a low order (fourth-order) nominal-plant model for a robust control design were evaluated: 1) by approximation based on the 'physics' of the process and 2) by an optimal Hankel approximation of a higher order plant model. The uncertainty between the nominal plant models and the higher order plant model is supplied as a specification to the ,u-synthesis robust control design procedure. Two methods of quantifying uncertainty were evaluated: 1) a combination of additive and multiplicative uncertainty and 2) multiplicative uncertainty alone. The conclusions are that the optimal Hankel approximation and a combination of additive and multiplicative uncertainty are the best approach to design robust control for this application. The results from nonlinear simulation testing and the physical experiments are consistent and thus help to confirm the correctness of the robust control design procedures and conclusions.

• Journal of Microbiology and Biotechnology
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• 제25권9호
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• pp.1429-1432
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• 2015

To identify plant-derived cell signaling inhibitors with antifungal properties, a twocomponent screening system using both wild-type Cryptococcus neoformans and a calcineurin mutant was employed owing to their counter-regulatory actions on the Hog1 mitogenactivated protein kinase and calcineurin pathways. Of the 2,000 plant extracts evaluated, a single bioactive compound from M. obovata Thunb. was found to act specifically on the calcineurin pathway of C. neoformans. This compound was identified as magnoloside A, and had potent antifungal activities against various Cryptococcus strains with minimum inhibitory concentration values ranging from 1.0 to 4.0 μg/ml.

• Journal of Microbiology
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• 제45권6호
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• pp.492-498
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• 2007

GacS and GacA proteins form a two component signal transduction system in bacteria. Here, Tn5 transposon gacS and gacA (Gac) mutants of Pseudomonas sp. KL28, an alkylphenol degrader, were isolated by selecting for smooth colonies of strain KL28. The mutants exhibited reduced ability to migrate on a solid surface. This surface motility does not require the action of flagella unlike the well-studied swarming motility of other Pseudomonas sp. The Gac mutants also showed reduced levels of biofilm and pellicle formation in liquid culture. In addition, compared to the wild type KL28 strain, these mutants were more resistant to high concentrations of m-cresol but were more sensitive to $H_2O_2$, which are characteristics that they share with an rpoS mutant. These results indicate that the Gac regulatory cascade in strain KL28 positively controls wrinkling morphology, biofilm formation, surface translocation and $H_2O_2$ resistance, which are important traits for its capacity to survive in particular niches.

• 생명과학회지
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• 제16권4호
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• pp.632-639
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• 2006

본 연구에서는 lacZ transcriptional fusion plasmid를 이용하여 광합성 세균인 Rhodobacter sphaeroides에서의 7가지 광합성유전자 (puf, puc, puhA, bchC, bchE, bchF, bchI) 발현의 경향과 조절을 조사하였다. R. sphaeroides에서 puhA와 bchI를 제외한 모든 광합성유전자들이 호기적 조건과 비교했을 때 혐기적 조건에서 더욱 강하게 발현되었다. puhA 유전자는 bchFNBHLM-RSP0290과 operon을 형성하며, bchI 유전자는 crtA와 operon을 이루는 것으로 나타났다. 광합성 조건에서 자란 R. sphaeroides의 puf, puc, bchCXYZ operon의 발현은 빛의 세기에 비례하는 반면, bchFNBHLM(RSP0290 puhA) operon의 발현은 빛의 세기에 반비례 하였다. bchEJG의 발현은 $10\;W/m^2$의 빛이 조사된 광합성 조건에서 제일 낮았으며, $100\;W/m^2$의 빛의 광합성 조건에서 가장 높았다. R. sphaeroides의 산소인지와 빛 인지에 관련된 세 가지 주요 조절기작에 의한 광합성유전자 조절은 다음과 같다. puf와 bchC는 PpsR repressor와 PrrBA two-component system에 의해 조절된다. 그리고 puc operon은 PpsR, FnrL, PrrBA system에 의해 조절된다. bchE의 발현은 FnrL과 PrrBA system에 의해 조절되는 반면, bchF는 오로지 PpsR에 의해서만 조절된다. PpsR repressor는 강한 세기의 빛 조건에서 bchf 발현억제의 원인이 되며, FnrL은 그 자체가 산소를 인지하는 기능 이외에도 세포질의 산화/환원 상태의 인지에 관련될 것으로 보인다.

• 한국임상약학회지
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• 제33권2호
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• pp.122-127
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• 2023

Background: This study was aimed to identify the safety signals of metoclopramide in Korea Adverse Event Reporting System (KAERS) database by proportionality analysis methods. Methods: The study was conducted using Korea Institute of Drug Safety and Risk Management-Korea Adverse Event Reporting System Database (KIDS-KD) reported from January 2013 to December 2017 through KAERS. Signals of metoclopramide that satisfied the data-mining indices of proportional reporting ratio (PRR), reporting odds ratio (ROR) and information component (IC) were defined. The detected signals were checked whether they included in drug labels in the Ministry of Food and Drug Safety (MFDS), U.S. Food and Drug Administration (FDA) and Micromedex^®. Results: A total number of drug AE reports associated with all drugs of data in this study was 2,665,429. Among them, the number of AE reports associated with metoclopramide was 22,583. Forty-two meaningful signals of metoclopramide were detected that satisfied with the criteria of data-mining indicies. Especially neurological signals including extrapyramidal reactions, represented in the safety letter of regulatory agencies were identified in this study. Conclusion: Neurological signals of metoclopramide including extrapyramidal reactions were detected. It is believed that this search for signals can contribute to ensuring safety in the use of metoclopramide.