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Peptide Transporter CstA Imports Pyruvate in Escherichia coli K-12
Hwang, Soonkyu,Choe, Donghui,Yoo, Minseob,Cho, Sanghyuk,Kim, Sun Chang,Cho, Suhyung,Cho, Byung-Kwan American Society for Microbiology [etc.] 2018 Journal of bacteriology Vol.200 No.7
<P><B>ABSTRACT</B></P><P>Pyruvate is an important intermediate of central carbon metabolism and connects a variety of metabolic pathways in Escherichia coli. Although the intracellular pyruvate concentration is dynamically altered and tightly balanced during cell growth, the pyruvate transport system remains unclear. Here, we identified a pyruvate transporter in E. coli using high-throughput transposon sequencing. The transposon mutant library (a total of 5 × 10<SUP>5</SUP> mutants) was serially grown with a toxic pyruvate analog (3-fluoropyruvate [3FP]) to enrich for transposon mutants lacking pyruvate transport function. A total of 52 candidates were selected on the basis of a stringent enrichment level of transposon insertion frequency in response to 3FP treatment. Subsequently, their pyruvate transporter function was examined by conventional functional assays, such as those measuring growth inhibition by the toxic pyruvate analog and pyruvate uptake activity. The pyruvate transporter system comprises CstA and YbdD, which are known as a peptide transporter and a conserved protein, respectively, whose functions are associated with carbon starvation conditions. In addition to the presence of more than one endogenous pyruvate importer, it has been suggested that the E. coli genome encodes constitutive and inducible pyruvate transporters. Our results demonstrated that CstA and YbdD comprise the constitutive pyruvate transporter system in E. coli, which is consistent with the tentative genomic locus previously suggested and the functional relationship with the extracellular pyruvate sensing system. The identification of this pyruvate transporter system provides valuable genetic information for understanding the complex process of pyruvate metabolism in E. coli.</P><P><B>IMPORTANCE</B> Pyruvate is an important metabolite as a central node in bacterial metabolism, and its intracellular levels are tightly regulated to maintain its functional roles in highly interconnected metabolic pathways. However, an understanding of the mechanism of how bacterial cells excrete and transport pyruvate remains elusive. Using high-throughput transposon sequencing followed by pyruvate uptake activity testing of the selected candidate genes, we found that a pyruvate transporter system comprising CstA and YbdD, currently annotated as a peptide transporter and a conserved protein, respectively, constitutively transports pyruvate. The identification of the physiological role of the pyruvate transporter system provides valuable genetic information for understanding the complex pyruvate metabolism in Escherichia coli.</P>
Soonkyu HWANG,Namil LEE,Donghui CHOE,Yongjae LEE,Woori KIM,Yujin JEONG,Suhyung CHO,Bernhard PALSSON,Byung-Kwan CHO 한국생물공학회 2021 한국생물공학회 학술대회 Vol.2021 No.10
Identification of transcriptional regulatory elements in the GC-rich Streptomyces genome is essential for the production of novel biochemicals from secondary metabolite biosynthetic gene clusters. We identified the transcriptional regulatory elements in β-lactam antibiotic-producing Streptomyces clavuligerus ATCC 27064 by determining transcript 3¢-end positions (TEPs) using term-seq. Termination of transcription was governed by three classes of TEPs, of which each displayed unique sequence features. The data integration with transcriptome data generated transcription units (TUs) and transcription unit clusters (TUCs). TU architecture showed that the transcript abundance in TU isoforms of a TUC was potentially affected by the sequence context of their TEPs. We also identified TU features of XRE family regulator and DUF397 domain-containing protein, showing the abundance of bidirectional TEPs. Finally, we found potential cis- and trans-regulatory elements that played a major role in 5’ and 3’-UTR. These findings highlight the role of the regulatory elements in transcription termination and posttranscriptional processing in Streptomyces sp.
Hwang, Soonkyu,An, Yun-Kyu,Kim, Ji-Min,Sohn, Hoon Elsevier 2019 Optics and lasers in engineering Vol.119 No.-
<P><B>Abstract</B></P> <P>This study proposes an integrated passive and active laser thermography (IPALT) system comprising a continuous wave (CW) laser and an infrared (IR) camera for fully noncontact monitoring and instantaneous evaluation of a fatigue crack in a metallic structure. The IPALT system operates in two phases: (1) passive thermography (PT) mode, and (2) active thermography (AT) mode. The PT mode monitors the fatigue crack initiation by measuring the thermoelastic effects on the fatigue crack tip in real time using the IR camera. Once the crack tip is identified, the AT mode is automatically triggered, and the corresponding fatigue crack is precisely quantified using the CW laser and the IR camera. Through this effective crack monitoring system under operating conditions, time dependent crack propagating behavior analysis, as well as early crack detection, can be achieved. The feasibility of the proposed IPALT system is experimentally validated by monitoring a metallic structure under a 10 Hz cyclic loading. The validation tests indicate that fatigue crack initiation is detected at 10,000 cycles by the PT mode, and the fatigue crack length is quantified as 10.45 mm with an accuracy of 99.43% compared to the microscope observed ground truth of 10.51 mm.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A novel integrated passive and active thermography (IPALT) system is proposed for real-time fatigue crack monitoring of metallic structures under operating conditions. </LI> <LI> The IPALT system retains and combines the advantages of both passive and active thermography techniques, and was experimentally validated through fatigue crack monitoring and quantification on a metallic structure. </LI> <LI> Monitoring and inspection can be performed in a completely noncontact, nondestructive, and nonintrusive manner. </LI> <LI> Automated visualization and quantification of a fatigue crack can be accomplished through the proposed single data acquisition and processing platform without interrupting the operating target structure or expert intervention. </LI> <LI> The fatigue crack monitoring and evaluation can be accomplished by only using current-state thermal images, making it possible to minimize false-alarms caused by environmental or operational variations. </LI> </UL> </P>
Soonkyu Hwang,Yun-Kyu An,Jinyeol Yang,Hoon Sohn 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.7 No.3
This study proposes a continuous line laser scanning thermography (CLLST) system for remote inspection of internal delamination in wind turbine blades. The CLLST system off ers the following advantages: (1) remote delamination inspection can be achieved by mechanically scanning a line laser beam and simultaneously capturing the corresponding thermal waves in nondestructive and noncontact manners; (2) internal delamination and surface damages can be classifi ed by analyzing laser-induced thermal wave propagating patterns; (3) instantaneous delamination detection and quantifi cation can be accomplished without using baseline data which is previously collected from the pristine condition of a target blade. To examine the feasibility of the CLLST system, laboratory and full-scale tests were performed using a carbon fi ber reinforced polymer (CFRP) plate, a 10 kW glass fi ber reinforced polymer (GFRP) wind turbine blade, and a 3 MW GFRP wind turbine blade. The test results demonstrated that the 10 mm diameter internal delamination located 1 mm underneath the blade surface was successfully detected even 10 m far from the target blade with a laser scanning speed of 2 mm/s.
Soonkyu Hwang,Ikgeun Jeon,Gayoung Han,Hoon Sohn,Wonjun Yun 국제구조공학회 2019 Smart Structures and Systems, An International Jou Vol.24 No.6
Triplex composite is an epoxy-bonded joint structure, which constitutes the secondary barrier in a liquefied natural gas (LNG) carrier. Defects in the triplex composite weaken its shear strength and may cause leakage of the LNG, thus compromising the structural integrity of the LNG carrier. This paper proposes an autonomous triplex composite inspection (ATCI) system for visualizing and classifying hidden defects in the triplex composite installed inside an LNG carrier. First, heat energy is generated on the surface of the triplex composite using halogen lamps, and the corresponding heat response is measured by an infrared (IR) camera. Next, the region of interest (ROI) is traced and noise components are removed to minimize false indications of defects. After a defect is identified, it is classified as internal void or uncured adhesive and its size and shape are quantified and visualized, respectively. The proposed ATCI system allows the fully automated and contactless detection, classification, and quantification of hidden defects inside the triplex composite. The effectiveness of the proposed ATCI system is validated using the data obtained from actual triplex composite installed in an LNG carrier membrane system.
Active Infrared Thermography for Visualizing Subsurface Micro Voids in an Epoxy Molding Compound
Yang, Jinyeol,Hwang, Soonkyu,Choi, Jaemook,Sohn, Hoon The Korean Society for Nondestructive Testing 2017 한국비파괴검사학회지 Vol.37 No.2
This paper presents an automated subsurface micro void detection technique based on pulsed infrared thermography for inspecting epoxy molding compounds (EMC) used in electronic device packaging. Subsurface micro voids are first detected and visualized by extracting a lock-in amplitude image from raw thermal images. Binary imaging follows to achieve better visualization of subsurface micro voids. A median filter is then applied for removing sparse noise components. The performance of the proposed technique is tested using 36 EMC samples, which have subsurface (below $150{\mu}m{\sim}300{\mu}m$ from the inspection surface) micro voids ($150{\mu}m{\sim}300{\mu}m$ in diameter). The experimental results show that the subsurface micro voids can be successfully detected without causing any damage to the EMC samples, making it suitable for automated online inspection.