Lim S

References (10)

Title : Thermostability enhancement of polyethylene terephthalate degrading PETase using self- and nonself-ligating protein scaffolding approaches - Sana_2023_Biotechnol.Bioeng__
Author(s) : Sana B , Ding K , Siau JW , Pasula RR , Chee S , Kharel S , Lena JH , Goh E , Rajamani L , Lam YM , Lim S , Ghadessy JF
Ref : Biotechnol Bioeng , : , 2023
Abstract : Polyethylene terephthalate (PET) hydrolase enzymes show promise for enzymatic PET degradation and green recycling of single-use PET vessels representing a major source of global pollution. Their full potential can be unlocked with enzyme engineering to render activities on recalcitrant PET substrates commensurate with cost-effective recycling at scale. Thermostability is a highly desirable property in industrial enzymes, often imparting increased robustness and significantly reducing quantities required. To date, most engineered PET hydrolases show improved thermostability over their parental enzymes. Here, we report engineered thermostable variants of Ideonella sakaiensis PET hydrolase enzyme (IsPETase) developed using two scaffolding strategies. The first employed SpyCatcher-SpyTag technology to covalently cyclize IsPETase, resulting in increased thermostability that was concomitant with reduced turnover of PET substrates compared to native IsPETase. The second approach using a GFP-nanobody fusion protein (vGFP) as a scaffold yielded a construct with a melting temperature of 80 degreesC. This was further increased to 85 degreesC when a thermostable PETase variant (FAST PETase) was scaffolded into vGFP, the highest reported so far for an engineered PET hydrolase derived from IsPETase. Thermostability enhancement using the vGFP scaffold did not compromise activity on PET compared to IsPETase. These contrasting results highlight potential topological and dynamic constraints imposed by scaffold choice as determinants of enzyme activity.
ESTHER : Sana_2023_Biotechnol.Bioeng__
PubMedSearch : Sana_2023_Biotechnol.Bioeng__
PubMedID: 37555384

Title : The influences of substrates' physical properties on enzymatic PET hydrolysis: Implications for PET hydrolase engineering - Pasula_2022_Eng.Biol_6_17
Author(s) : Pasula RR , Lim S , Ghadessy FJ , Sana B
Ref : Eng Biol , 6 :17 , 2022
Abstract : Plastic pollution in diverse terrestrial and marine environments is a widely recognised and growing problem. Bio-recycling and upcycling of plastic waste is a potential solution to plastic pollution, as these processes convert plastic waste into useful materials. Polyethylene terephthalate (PET) is the most abundant plastic waste, and this material can be degraded by a class of recently discovered bacterial esterase enzymes known as PET hydrolases (PETase). Investigations of the enzymatic hydrolysis of diverse PET molecules have clearly revealed that the biodegradability of various PET substrates depends on both their chemical structure and physical properties, including polymer length, crystallinity, glass transition temperature, surface area, and surface charge. This review summarises the known impacts of crystallinity and other physical properties on enzymatic PET hydrolysis.
ESTHER : Pasula_2022_Eng.Biol_6_17
PubMedSearch : Pasula_2022_Eng.Biol_6_17
PubMedID: 36968557

Title : Chemo-Biological Upcycling of Poly(ethylene terephthalate) to Multifunctional Coating Materials - Kim_2021_ChemSusChem_14_4251
Author(s) : Kim HT , Ryu MH , Jung YJ , Lim S , Song HM , Park J , Hwang SY , Lee HS , Yeon YJ , Sung BH , Bornscheuer UT , Park SJ , Joo JC , Oh DX
Ref : ChemSusChem , 14 :4251 , 2021
Abstract : Chemo-biological upcycling of poly(ethylene terephthalate) (PET) developed in this study includes the following key steps: chemo-enzymatic PET depolymerization, biotransformation of terephthalic acid (TPA) into catechol, and its application as a coating agent. Monomeric units were first produced through PET glycolysis into bis(2-hydroxyethyl) terephthalate (BHET), mono(2-hydroxyethyl) terephthalate (MHET), and PET oligomers and enzymatic hydrolysis of these glycolyzed products using Bacillus subtilis esterase (Bs2Est). Bs2Est efficiently hydrolyzed glycolyzed products into TPA as a key enzyme for chemo-enzymatic depolymerization. Furthermore, catechol solution produced from TPA via a whole-cell biotransformation (Escherichia coli) could be directly used for functional coating on various substrates just after simple cell removal from the culture medium without further purification and water-evaporation. This work demonstrates a proof-of-concept of a PET upcycling strategy via a combination of chemo-biological conversion of PET waste into multifunctional coating materials.
ESTHER : Kim_2021_ChemSusChem_14_4251
PubMedSearch : Kim_2021_ChemSusChem_14_4251
PubMedID: 34339110
Gene_locus related to this paper: bacsu-pnbae

Title : Application of the RBBP9 Serine Hydrolase Inhibitor, ML114, Decouples Human Pluripotent Stem Cell Proliferation and Differentiation - Lim_2020_Int.J.Mol.Sci_21_8983
Author(s) : Lim S , Shparberg RA , Coorssen JR , O'Connor MD
Ref : Int J Mol Sci , 21 : , 2020
Abstract : Retinoblastoma binding protein 9 (RBBP9) is required for maintaining the expression of both pluripotency and cell cycle genes in human pluripotent stem cells (hPSCs). An siRNA-based study from our group showed it does so by influencing cell cycle progression through the RB/E2F pathway. In non-pluripotent cells, RBBP9 is also known to have serine hydrolase (SH) activity, acting on currently undefined target proteins. The role of RBBP9 SH activity in hPSCs, and during normal development, is currently unknown. To begin assessing whether RBBP9 SH activity might contribute to hPSC maintenance, hPSCs were treated with ML114-a selective chemical inhibitor of RBBP9 SH activity. Stem cells treated with ML114 showed significantly reduced population growth rate, colony size and progression through the cell cycle, with no observable change in cell morphology or decrease in pluripotency antigen expression-suggesting no initiation of hPSC differentiation. Consistent with this, hPSCs treated with ML114 retained the capacity for tri-lineage differentiation, as seen through teratoma formation. Subsequent microarray and Western blot analyses of ML114-treated hPSCs suggest the nuclear transcription factor Y subunit A (NFYA) may be a candidate effector of RBBP9 SH activity in hPSCs. These data support a role for RBBP9 in regulating hPSC proliferation independent of differentiation, whereby inhibition of RBBP9 SH activity de-couples decreased hPSC proliferation from initiation of differentiation.
ESTHER : Lim_2020_Int.J.Mol.Sci_21_8983
PubMedSearch : Lim_2020_Int.J.Mol.Sci_21_8983
PubMedID: 33256189
Gene_locus related to this paper: human-RBBP9

Title : Flavisolibacter tropicus sp. nov., isolated from tropical soil - Lee_2016_Int.J.Syst.Evol.Microbiol_66_3413
Author(s) : Lee JJ , Kang MS , Kim GS , Lee CS , Lim S , Lee J , Roh SH , Kang H , Ha JM , Bae S , Jung HY , Kim MK
Ref : Int J Syst Evol Microbiol , 66 :3413 , 2016
Abstract : A Gram-stain-negative, non-motile, deep yellow, rod-shaped bacterium, designated strain LCS9T, was isolated from a soil sample at the tropical zone within the Ecorium of the National Institute of Ecology in Seocheon, central-western Korea. 16S rRNA gene sequence analysis showed that strain LCS9T clustered with members of the genus Flavisolibacter of the family Chitinophagaceae, phylum Bacteroidetes. Sequence similarities between strain LCS9T and the type strains of the genus Flavisolibacter ranged from 94.6 to 94.9 %. Strain LCS9T grew at 10-37 degrees C (optimum, 25 degrees C) and at pH 6.0-10.0 (optimum, pH 7); was positive for catalase and oxidase; and negative for nitrate reduction and production of indole. Cells showed pigment absorbance peaks at 451 and 479 nm, and had 0.03 % survival following exposure to 3 kGy gamma radiation. Strain LCS9T had the following chemotaxonomic characteristics: the major quinone was menaquinone-7 (MK-7); the major fatty acids were iso-C15 : 0 and iso-C17 : 0 3-OH; polar lipids included phosphoatidylethanolamine, an unidentified aminophospholipid, unidentified aminolipidsand unidentified lipids. The DNA G+C content was 39.4 mol%. Based on polyphasic analysis, the type strain LCS9T (=KCTC 42070T=JCM 19972T) represents a novel species for which the name Flavisolibacter tropicus sp. nov. is proposed. Radiation resistance in the genus Flavisolibacter has not been reported to date, and so this is the first report of low-level radiation resistance of a member of the genus.
ESTHER : Lee_2016_Int.J.Syst.Evol.Microbiol_66_3413
PubMedSearch : Lee_2016_Int.J.Syst.Evol.Microbiol_66_3413
PubMedID: 27259556
Gene_locus related to this paper: 9bact-a0a172try1

Title : Spirosoma radiotolerans sp. nov., a gamma-radiation-resistant bacterium isolated from gamma ray-irradiated soil - Lee_2014_Curr.Microbiol_69_286
Author(s) : Lee JJ , Srinivasan S , Lim S , Joe M , Im S , Bae SI , Park KR , Han JH , Park SH , Joo BM , Park SJ , Kim MK
Ref : Curr Microbiol , 69 :286 , 2014
Abstract : A Gram-negative, short-rod-shaped bacterial strain with gliding motility, designated as DG5A(T), was isolated from a rice field soil in South Korea. Phylogenic analysis using 16S rRNA gene sequence of the new isolate showed that strain DG5A(T) belong to the genus Spirosoma in the family Spirosomaceae, and the highest sequence similarities were 95.5 % with Spirosoma linguale DSM 74(T), 93.4 % with Spirosoma rigui WPCB118(T), 92.8 % with Spirosoma luteum SPM-10(T), 92.7 % with Spirosoma spitsbergense SPM-9(T), and 91.9 % with Spirosoma panaciterrae Gsoil 1519(T). Strain DG5A(T) revealed resistance to gamma and UV radiation. Chemotaxonomic data showed that the most abundant fatty acids were summed feature C(16:1) omega7c/C(16:1) omega6c (36.90 %), C(16:1) omega5c (29.55 %), and iso-C(15:0) (14.78 %), and the major polar lipid was phosphatidylethanolamine (PE). The DNA G+C content of strain DG5A(T) was 49.1 mol%. Together, the phenotypic, phylogenetic, and chemotaxonomic data supported that strain DG5A(T) presents a novel species of the genus Spirosoma, for which the name Spirosoma radiotolerans sp. nov., is proposed. The type strain is DG5A(T) (=KCTC 32455(T) = JCM19447(T)).
ESTHER : Lee_2014_Curr.Microbiol_69_286
PubMedSearch : Lee_2014_Curr.Microbiol_69_286
PubMedID: 24748440
Gene_locus related to this paper: 9bact-a0a0e3v606 , 9bact-a0a0e3zrk0 , 9bact-a0a0e3zva1 , 9bact-a0a0e3zvi6 , 9bact-a0a0e3zsw1 , 9bact-a0a0e3vah2 , 9bact-a0a0e4a055

Title : Low-dose theophylline does not exert its anti-inflammatory effects in mild asthma through upregulation of interleukin-10 in alveolar macrophages - Oliver_2001_Allergy_56_1087
Author(s) : Oliver B , Tomita K , Keller A , Caramori G , Adcock I , Chung KF , Barnes PJ , Lim S
Ref : Allergy , 56 :1087 , 2001
Abstract : BACKGROUND: There is accumulating evidence that theophylline has anti-inflammatory or immunomodulatory effects. This may be, in part, mediated via an upregulation in the production of the anti-inflammatory cytokine interleukin (IL)-10. We determined whether low-dose theophylline (LDT) would increase the production of IL-10, and attenuate the production of proinflammatory cytokines by alveolar macrophages.
METHODS: In a double-blind, placebo-controlled, crossover study involving 15 steroid-free patients with mild asthma, fiberoptic bronchoscopy and bronchoalveolar lavage (BAL) were performed at the end of the treatment and placebo periods. Alveolar macrophages were cultured in vitro, and we measured their release of IL-10, GM-CSF, and TNF-alpha. We also measured IL-10 production in whole blood together with the number of monocytes and T cells expressing intracellular IL-10 by flow cytometry.
RESULTS: LDT did not increase the production of IL-10, or attenuate the production of GM-CSF or TNF-alpha by alveolar macrophages. However, after theophylline treatment, there was a significant reduction in mean (SD) (95% CI) BAL eosinophil number from 3.4 (1.7)% (95% CI 2.4-4.4) to 1.7 (1.0)% (95% CI 1.1-2.3) compared with placebo (P<0.05). Similarly, there was no increase in whole-blood IL-10 release or in the number of monocytes and T cells expressing intracellular IL-10 after treatment.
CONCLUSIONS: LDT has an anti-inflammatory effect in asthma; however, this effect is not mediated via the production of IL-10 or the attenuation of GM-CSF or TNF-alpha. The mechanisms of theophylline activity remain to be determined.
ESTHER : Oliver_2001_Allergy_56_1087
PubMedSearch : Oliver_2001_Allergy_56_1087
PubMedID: 11703224

Title : Effect of inhaled budesonide on lung function and airway inflammation. Assessment by various inflammatory markers in mild asthma - Lim_1999_Am.J.Respir.Crit.Care.Med_159_22
Author(s) : Lim S , Jatakanon A , John M , Gilbey T , O'Connor B J , Chung KF , Barnes PJ
Ref : American Journal of Respiratory & Critical Care Medicine , 159 :22 , 1999
Abstract : In a double-blind, cross-over study, we examined the effect of inhaled budesonide (800 microgram twice daily via Turbohaler) on lung function and various markers of airway inflammation including airway responsiveness to methacholine (PC20), exhaled nitric oxide (NO), eosinophils in induced sputum, bronchoalveolar lavage (BAL), and airway biopsies from 14 patients with mild asthma needing beta2- agonist therapy only. After inhaled steroids, there was a significant increase in FEV1 and PC20, and reduction in exhaled NO. Eosinophils in induced sputum and airway biopsy sections were also significantly decreased, although BAL eosinophil counts remained unchanged. At baseline, significant correlations were observed between exhaled NO and PC20 methacholine (r = 0.64, p < 0.05), exhaled NO and peak expiratory flow rate (PEFR) variability (r = 0. 65, p < 0.05), sputum eosinophils and FEV1 (r = -0.63, p = 0.05), and sputum eosinophils and log PC20 methacholine (r = -0.67, p < 0. 05). After treatment with inhaled steroids, there was a significant correlation between eosinophils in biopsy sections, and BAL, with log PC20 methacholine. It is likely that these parameters represent different aspects of the inflammatory process, which are all inhibited by inhaled steroids.
ESTHER : Lim_1999_Am.J.Respir.Crit.Care.Med_159_22
PubMedSearch : Lim_1999_Am.J.Respir.Crit.Care.Med_159_22
PubMedID: 9872813

Title : Combined use of exhaled hydrogen peroxide and nitric oxide in monitoring asthma - Horvath_1998_Am.J.Respir.Crit.Care.Med_158_1042
Author(s) : Horvath I , Donnelly LE , Kiss A , Kharitonov SA , Lim S , Chung KF , Barnes PJ
Ref : American Journal of Respiratory & Critical Care Medicine , 158 :1042 , 1998
Abstract : Oxidative stress contributes to airway inflammation and exhaled hydrogen peroxide (H2O2) and nitric oxide (NO) are elevated in asthmatic patients. We determined the concentrations of expired H2O2 and NO in 116 asthmatic (72 stable steroid-naive, 30 stable steroid-treated, and 14 severe steroid-treated unstable patients) and in 35 healthy subjects, and studied the relation between exhaled H2O2, NO, FEV1, airway responsiveness, and eosinophils in induced sputum. Both exhaled H2O2 and NO levels were elevated in steroid-naive asthmatic patients compared with normal subjects (0.72 +/- 0.06 versus 0.27 +/- 0.04 microM and 29 +/- 1.9 versus 6.5 +/- 0. 32 ppb, respectively; p < 0.001) and were reduced in stable steroid-treated patients (0.43 +/- 0.08 microM, p < 0.05, and 9.9 +/- 0.97 ppb, p < 0.001). In unstable steroid-treated asthmatics, however, H2O2 levels were increased, but exhaled NO levels were low (0.78 +/- 0.16 microM and 6.7 +/- 1.0 ppb, respectively). There was a correlation between expired H2O2, sputum eosinophils and airway hyperresponsiveness (methacholine PC20). Exhaled NO also correlated with sputum eosinophils, but not with airway hyperresponsiveness. Our findings indicate that measurement of expired H2O2 and NO in asthmatic patients provides complementary data for monitoring of disease activity.
ESTHER : Horvath_1998_Am.J.Respir.Crit.Care.Med_158_1042
PubMedSearch : Horvath_1998_Am.J.Respir.Crit.Care.Med_158_1042
PubMedID: 9769258

Title : Correlation between exhaled nitric oxide, sputum eosinophils, and methacholine responsiveness in patients with mild asthma - Jatakanon_1998_Thorax_53_91
Author(s) : Jatakanon A , Lim S , Kharitonov SA , Chung KF , Barnes PJ
Ref : Thorax , 53 :91 , 1998
Abstract : BACKGROUND: Eosinophils in induced sputum and exhaled nitric oxide (NO) are currently used as non-invasive markers in the assessment of airway inflammation in asthma. As both sputum eosinophils (%) and exhaled NO are raised in asthmatic subjects not receiving inhaled steroids and decreased following corticosteroid therapy, a relationship between them is plausible.
METHODS: Exhaled NO was measured by chemiluminescence analyser, sputum induction by 3.5% saline inhalation, and bronchial responsiveness was measured as PC20FEV1 methacholine in 35 stable asthmatic patients using beta 2 agonist alone and the correlation between these non-invasive markers of airway inflammation was studied.
RESULTS: There were significant correlations between exhaled NO and PC20 (r = -0.64), exhaled NO and sputum eosinophils (%) (r = 0.48), and also between sputum eosinophils (%) and PC20 (r = -0.40). CONCLUSION: The correlation between exhaled NO and PC20 suggests that exhaled NO or the mechanisms leading to its increase may contribute to airway hyperresponsiveness in asthma. Furthermore, the relationship between sputum eosinophils (%), exhaled NO, and PC20 highlight the potential use of eosinophils (%) in induced sputum and exhaled NO to monitor the severity of asthma.
ESTHER : Jatakanon_1998_Thorax_53_91
PubMedSearch : Jatakanon_1998_Thorax_53_91
PubMedID: 9624291