Publications by authors named "So-Hee Son"

7 Publications

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Pairing of orthogonal chaperones with a cytochrome P450 enhances terpene synthesis in Saccharomyces cerevisiae.

Biotechnol J 2021 Jul 16:e2000452. Epub 2021 Jul 16.

Research Center for Bio-based Chemistry, Korea Research Institute of Chemical Technology (KRICT), Ulsan, Republic of Korea.

The supply of terpenes is often limited by their low extraction yield from natural resources, such as plants. Thus, microbial biosynthesis has emerged as an attractive platform for the production of terpenes. Many strategies have been applied to engineer microbes to improve terpene production capabilities; however, functional expression of heterologous proteins such as cytochrome P450 enzymes (P450s) in microbes is a major obstacle. This study reports the successful pairing of cognate chaperones and P450s for functional heterologous expression in Saccharomyces cerevisiae. This chaperone pairing was exploited to facilitate the functional assembly of the protopanaxadiol (PPD) biosynthesis pathway, which consists of a P450 oxygenase and a P450 reductase redox partner originating from Panax ginseng and Arabidopsis thaliana, respectively. We identified several chaperones required for protein folding in P. ginseng and A. thaliana and evaluated the impact of the coexpression of the corresponding chaperones on the synthesis and activity of PPD biosynthesis enzymes. Expression of a chaperone from P. ginseng (PgCPR5), a cognate of PPD biosynthesis enzymes, significantly increased PPD production by more than 2.5-fold compared with that in the corresponding control strain. Thus, pairing of chaperones with heterologous enzymes provides an effective strategy for the construction of challenging biosynthesis pathways in yeast.
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http://dx.doi.org/10.1002/biot.202000452DOI Listing
July 2021

Engineering Cell Wall Integrity Enables Enhanced Squalene Production in Yeast.

J Agric Food Chem 2020 Apr 17;68(17):4922-4929. Epub 2020 Apr 17.

Research Center for Bio-based Chemistry, Korea Research Institute of Chemical Technology (KRICT), 406-30, Jongga-ro, Jung-gu, Ulsan 44429, Republic of Korea.

Microbial production of many lipophilic compounds is often limited by product toxicity to host cells. Engineering cell walls can help mitigate the damage caused by lipophilic compounds by increasing tolerance to those compounds. To determine if the cell wall engineering would be effective in enhancing lipophilic compound production, we used a previously constructed squalene-overproducing yeast strain (SQ) that produces over 600 mg/L of squalene, a model membrane-damaging lipophilic compound. This SQ strain had significantly decreased membrane rigidity, leading to increased cell lysis during fermentation. The SQ strain was engineered to restore membrane rigidity by activating the cell wall integrity (CWI) pathway, thereby further enhancing its squalene production efficiency. Maintenance of CWI was associated with improved squalene production, as shown by cell wall remodeling through regulation of Ecm33, a key regulator of the CWI pathway. Deletion of in the SQ strain helped restore membrane rigidity and improve stress tolerance. Moreover, deletion suppressed cell lysis and increased squalene production by approximately 12% compared to that by the parent SQ strain. Thus, this study shows that engineering of the yeast cell wall is a promising strategy for enhancing the physiological functions of industrial strains for production of lipophilic compounds.
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http://dx.doi.org/10.1021/acs.jafc.0c00967DOI Listing
April 2020

Circulating Tumor Cell Number Is Associated with Primary Tumor Volume in Patients with Lung Adenocarcinoma.

Tuberc Respir Dis (Seoul) 2020 Jan;83(1):61-70

Liquid Biopsy and Precision Medicine Division, Clinomics Inc., Ulsan, Korea.

Background: Circulating tumor cells (CTCs) are frequently detected in patients with advanced-stage malignant tumors and could act as a predictor of poor prognosis. However, there is a paucity of data on the relationship between CTC number and primary tumor volume in patients with lung cancer. Therefore, our study aimed to evaluate the relationship between CTC number and primary tumor volume in patients with lung adenocarcinoma.

Methods: We collected blood samples from 21 patients with treatment-naive lung adenocarcinoma and 73 healthy individuals. To count CTCs, we used a CTC enrichment method based on fluid-assisted separation technology. We compared CTC numbers between lung adenocarcinoma patients and healthy individuals using propensity score matching, and performed linear regression analysis to analyze the relationship between CTC number and primary tumor volume in lung adenocarcinoma patients.

Results: CTC positivity was significantly more common in lung adenocarcinoma patients than in healthy individuals (p<0.001). The median primary tumor volume in CTC-negative and CTC-positive patients was 10.0 cm³ and 64.8 cm³, respectively. Multiple linear regression analysis showed that the number of CTCs correlated with primary tumor volume in lung adenocarcinoma patients (β=0.903, p=0.002). Further subgroup analysis showed a correlation between CTC number and primary tumor volume in patients with distant (p=0.024) and extra-thoracic (p=0.033) metastasis (not in patients with distant metastasis).

Conclusion: Our study showed that CTC numbers may be associated with primary tumor volume in lung adenocarcinomas patients, especially in those with distant metastasis.
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http://dx.doi.org/10.4046/trd.2019.0048DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6953495PMC
January 2020

Tailoring the Saccharomyces cerevisiae endoplasmic reticulum for functional assembly of terpene synthesis pathway.

Metab Eng 2019 12 21;56:50-59. Epub 2019 Aug 21.

Research Center for Bio-based Chemistry, Korea Research Institute of Chemical Technology (KRICT), 406-30, Jongga-ro, Jung-gu, Ulsan, 44429, Republic of Korea. Electronic address:

The endoplasmic reticulum (ER) is a dynamic organelle that synthesizes and folds proteins. An imbalance between the ER protein synthesis load and its folding capacity triggers the unfolded protein response, thereby restoring normal ER functions via size adjustment. Inspired by such inherent genetic programming events, we engineered Saccharomyces cerevisiae to expand the ER by overexpressing a key ER size regulatory factor, INO2. ER space expansion enhanced ER protein synthesis and folding capacity, and relieved metabolic constraints imposed by the limited enzyme abundance. Harnessing the yeast ER for metabolic engineering, we ultimately increased the production of squalene and cytochrome P450-mediated protopanaxadiol by 71-fold and 8-fold, compared to their respective control strains without overexpression of INO2. Furthermore, genome-wide transcriptome analysis of the ER-expanded strain revealed that the significant improvement in terpene production was associated with global rewiring of the metabolic network. Therefore, the yeast ER can be engineered as a specialized compartment for enhancing terpene production, representing new possibilities for the high-level production of other value-added chemicals.
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http://dx.doi.org/10.1016/j.ymben.2019.08.013DOI Listing
December 2019

Development of Dissociation-Enhanced Lanthanide Fluoroimmunoassay for Measuring Leptin.

J Fluoresc 2016 Sep 24;26(5):1715-21. Epub 2016 Jun 24.

Research Group of Bioprocess Engineering, Korea Food Research Institute, Seongnam, 13539, Republic of Korea.

Development of a dissociation-enhanced lanthanide fluoroimmunoassay (DELFIA) for measuring leptin, a satiety hormone of appetite control, was conducted in sandwich assay format exploiting a microplate immobilized with an anti-leptin antibody and another antibody raised against leptin and tagged with an europium chelate. In the leptin DELFIA of this study, amounts of antibody coated to the microplate and of the bioconjugate for the second immune reaction were optimized as 0.5 μg and 200 ng per well, respectively. When plotted in double-logarithmic scale, a linear relationship of y (log10 response signal) = 0.6023× (log10 leptin concentration) + 3.4084 (r(2) = 0.9646) was obtained at the leptin concentrations of 0.01─50 ng/mL with the limit of detection of 0.01 ng/mL. Individual leptin concentrations in various samples were well convergent to the calibration curve of the current assay. When applied to the measurement of leptin in a rat serum, the present assay was found quite effective and was competitive to a commercial sandwich-type ELISA.
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http://dx.doi.org/10.1007/s10895-016-1862-8DOI Listing
September 2016

Development of Antigen-Immobilized Metallothionein Sensor that Exploits Gold Nanoparticle-Based Enhancement of Signal.

J Nanosci Nanotechnol 2015 Aug;15(8):6188-92

An antigen-immobilized indirect-competitive immunosensor that detects metallothionein (MT), a potent biomarker of contamination with heavy metals, was developed exploiting enhancement of signal based on an additional binding of gold nanoparticles to an anti-MT antibody through the biotin-avidin interaction. The sensor was constructed by the immobilization of MT at 1 mg/mL on a 9-MHz quartz crystal microbalance and the concentration of the antibody for competitive reaction was optimized as 10 µg/mL based on the degree of sensor response. At this moment, the control response of the sensor obtained with enhancement of signal was 343.8 Hz and was larger than that without enhancement of signal 2.47 fold. The sensor responses decreased gradually with increasing analyte concentrations, and a linear relationship between analyte concentration and sensor response was acquired in the range of 0.005-1 ng/mL MT in double-logarithmic scales with a correlation coefficient (r) of 0.9858. The limit of detection of the present sensor was presumed to be present below 5 pg/mL MT.
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http://dx.doi.org/10.1166/jnn.2015.10297DOI Listing
August 2015

Enzymatic hydrolysis of anchovy fine powder at high and ambient pressure, and characterization of the hydrolyzates.

J Sci Food Agric 2016 Feb 9;96(3):970-8. Epub 2015 Apr 9.

Research Group of Bioprocess Engineering, Korea Food Research Institute, Seongnam, Gyonggi 463-746, Republic of Korea.

Background: At specific conditions of high pressure, the stability and activity of some enzymes are reportedly known to increase. The aim of this study was to apply pressure-tolerant proteases to hydrolyzing anchovy fine powder (AFP) and to determine product characteristics of the resultant hydrolyzates.

Results: Anchovy fine powder enzyme hydrolyzates (AFPEHs) were produced at 300 MPa and ambient pressure using combinations of Flavourzyme 500MG, Alcalase 2.4L, Marugoto E and Protamex. When the same protease combination was used for hydrolysis, the contents of total soluble solids, total water-soluble nitrogen and trichloroacetic acid-soluble nitrogen in the AFPEHs produced at 300 MPa were conspicuously higher than those in the AFPEHs produced at ambient pressure. This result and electrophoretic characteristics indicated that the high-pressure process of this study accelerates protein hydrolysis compared with the ambient-pressure counterpart. Most peptides in the hydrolyzates obtained at 300 MPa had molecular masses less than 5 kDa. Functionality, sensory characteristics and the content of total free amino acids of selected hydrolyzates were also determined.

Conclusion: The high-pressure hydrolytic process utilizing pressure-tolerant proteases was found to be an efficient method for producing protein hydrolyzates with good product characteristics.
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http://dx.doi.org/10.1002/jsfa.7173DOI Listing
February 2016
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