Johnson CW

References (5)

Title : Concentration-dependent inhibition of mesophilic PETases on poly(ethylene terephthalate) can be eliminated by enzyme engineering - Avilan_2023_ChemSusChem__e202202277
Author(s) : Avilan L , Lichtenstein BR , Koenig G , Zahn M , Allen MD , Oliveira L , Clark M , Bemmer V , Graham R , Austin HP , Dominick G , Johnson CW , Beckham GT , McGeehan J , Pickford AR
Ref : ChemSusChem , :e202202277 , 2023
Abstract : Enzyme-based depolymerization is a viable approach for recycling of poly(ethylene terephthalate) (PET). PETase from Ideonella sakaiensis (IsPETase) is capable of PET hydrolysis under mild conditions but suffers from concentration-dependent inhibition. Here, we report that this inhibition is dependent on incubation time, the solution conditions and PET surface area. Furthermore, this inhibition is evident in other mesophilic PET-degrading enzymes to varying degrees, independent of the level of PET depolymerization activity. The inhibition has no clear structural basis, but moderately thermostable IsPETase variants exhibit reduced inhibition, and the property is completely absent in the highly thermostable HotPETase, previously engineered by directed evolution, which our simulations suggest results from reduced flexibility around the active site. This work highlights a limitation in applying natural mesophilic hydrolases for PET hydrolysis, and reveals an unexpected positive outcome of engineering these enzymes for enhanced thermostability.
ESTHER : Avilan_2023_ChemSusChem__e202202277
PubMedSearch : Avilan_2023_ChemSusChem__e202202277
PubMedID: 36811288
Gene_locus related to this paper: psea4-u2z2l5 , 9gamm-a0a031mkr8 , 9burk-a0a1w6l438 , 9psed-a0a078mgg8 , pseol-e9kjl1 , 9burk-a0a0g3bi90 , 9burk-a0a1w6l588 , idesa-peth , acide-PBSA

Title : Tandem chemical deconstruction and biological upcycling of poly(ethylene terephthalate) to beta-ketoadipic acid by Pseudomonas putida KT2440 - Werner_2021_Metab.Eng_67_250
Author(s) : Werner AZ , Clare R , Mand TD , Pardo I , Ramirez KJ , Haugen SJ , Bratti F , Dexter GN , Elmore JR , Huenemann JD , Peabody GLt , Johnson CW , Rorrer NA , Salvachua D , Guss AM , Beckham GT
Ref : Metab Eng , 67 :250 , 2021
Abstract : Poly(ethylene terephthalate) (PET) is the most abundantly consumed synthetic polyester and accordingly a major source of plastic waste. The development of chemocatalytic approaches for PET depolymerization to monomers offers new options for open-loop upcycling of PET, which can leverage biological transformations to higher-value products. To that end, here we perform four sequential metabolic engineering efforts in Pseudomonas putida KT2440 to enable the conversion of PET glycolysis products via: (i) ethylene glycol utilization by constitutive expression of native genes, (ii) terephthalate (TPA) catabolism by expression of tphA2(II)A3(II)B(II)A1(II) from Comamonas and tpaK from Rhodococcus jostii, (iii) bis(2-hydroxyethyl) terephthalate (BHET) hydrolysis to TPA by expression of PETase and MHETase from Ideonella sakaiensis, and (iv) BHET conversion to a performance-advantaged bioproduct, beta-ketoadipic acid (betaKA) by deletion of pcaIJ. Using this strain, we demonstrate production of 15.1 g/L betaKA from BHET at 76% molar yield in bioreactors and conversion of catalytically depolymerized PET to betaKA. Overall, this work highlights the potential of tandem catalytic deconstruction and biological conversion as a means to upcycle waste PET.
ESTHER : Werner_2021_Metab.Eng_67_250
PubMedSearch : Werner_2021_Metab.Eng_67_250
PubMedID: 34265401
Gene_locus related to this paper: idesa-mheth , idesa-peth

Title : Characterization and engineering of a two-enzyme system for plastics depolymerization - Knott_2020_Proc.Natl.Acad.Sci.U.S.A_117_25476
Author(s) : Knott BC , Erickson E , Allen MD , Gado JE , Graham R , Kearns FL , Pardo I , Topuzlu E , Anderson JJ , Austin HP , Dominick G , Johnson CW , Rorrer NA , Szostkiewicz CJ , Copie V , Payne CM , Woodcock HL , Donohoe BS , Beckham GT , McGeehan JE
Ref : Proc Natl Acad Sci U S A , 117 :25476 , 2020
Abstract : Plastics pollution represents a global environmental crisis. In response, microbes are evolving the capacity to utilize synthetic polymers as carbon and energy sources. Recently, Ideonella sakaiensis was reported to secrete a two-enzyme system to deconstruct polyethylene terephthalate (PET) to its constituent monomers. Specifically, the I. sakaiensis PETase depolymerizes PET, liberating soluble products, including mono(2-hydroxyethyl) terephthalate (MHET), which is cleaved to terephthalic acid and ethylene glycol by MHETase. Here, we report a 1.6 A resolution MHETase structure, illustrating that the MHETase core domain is similar to PETase, capped by a lid domain. Simulations of the catalytic itinerary predict that MHETase follows the canonical two-step serine hydrolase mechanism. Bioinformatics analysis suggests that MHETase evolved from ferulic acid esterases, and two homologous enzymes are shown to exhibit MHET turnover. Analysis of the two homologous enzymes and the MHETase S131G mutant demonstrates the importance of this residue for accommodation of MHET in the active site. We also demonstrate that the MHETase lid is crucial for hydrolysis of MHET and, furthermore, that MHETase does not turnover mono(2-hydroxyethyl)-furanoate or mono(2-hydroxyethyl)-isophthalate. A highly synergistic relationship between PETase and MHETase was observed for the conversion of amorphous PET film to monomers across all nonzero MHETase concentrations tested. Finally, we compare the performance of MHETase:PETase chimeric proteins of varying linker lengths, which all exhibit improved PET and MHET turnover relative to the free enzymes. Together, these results offer insights into the two-enzyme PET depolymerization system and will inform future efforts in the biological deconstruction and upcycling of mixed plastics.
ESTHER : Knott_2020_Proc.Natl.Acad.Sci.U.S.A_117_25476
PubMedSearch : Knott_2020_Proc.Natl.Acad.Sci.U.S.A_117_25476
PubMedID: 32989159
Gene_locus related to this paper: idesa-mheth

Title : Characterization and engineering of a plastic-degrading aromatic polyesterase - Austin_2018_Proc.Natl.Acad.Sci.U.S.A_115_E4350
Author(s) : Austin HP , Allen MD , Donohoe BS , Rorrer NA , Kearns FL , Silveira RL , Pollard BC , Dominick G , Duman R , El Omari K , Mykhaylyk V , Wagner A , Michener WE , Amore A , Skaf MS , Crowley MF , Thorne AW , Johnson CW , Woodcock HL , McGeehan JE , Beckham GT
Ref : Proc Natl Acad Sci U S A , 115 :E4350 , 2018
Abstract : Poly(ethylene terephthalate) (PET) is one of the most abundantly produced synthetic polymers and is accumulating in the environment at a staggering rate as discarded packaging and textiles. The properties that make PET so useful also endow it with an alarming resistance to biodegradation, likely lasting centuries in the environment. Our collective reliance on PET and other plastics means that this buildup will continue unless solutions are found. Recently, a newly discovered bacterium, Ideonella sakaiensis 201-F6, was shown to exhibit the rare ability to grow on PET as a major carbon and energy source. Central to its PET biodegradation capability is a secreted PETase (PET-digesting enzyme). Here, we present a 0.92 A resolution X-ray crystal structure of PETase, which reveals features common to both cutinases and lipases. PETase retains the ancestral alpha/beta-hydrolase fold but exhibits a more open active-site cleft than homologous cutinases. By narrowing the binding cleft via mutation of two active-site residues to conserved amino acids in cutinases, we surprisingly observe improved PET degradation, suggesting that PETase is not fully optimized for crystalline PET degradation, despite presumably evolving in a PET-rich environment. Additionally, we show that PETase degrades another semiaromatic polyester, polyethylene-2,5-furandicarboxylate (PEF), which is an emerging, bioderived PET replacement with improved barrier properties. In contrast, PETase does not degrade aliphatic polyesters, suggesting that it is generally an aromatic polyesterase. These findings suggest that additional protein engineering to increase PETase performance is realistic and highlight the need for further developments of structure/activity relationships for biodegradation of synthetic polyesters.
ESTHER : Austin_2018_Proc.Natl.Acad.Sci.U.S.A_115_E4350
PubMedSearch : Austin_2018_Proc.Natl.Acad.Sci.U.S.A_115_E4350
PubMedID: 29666242
Gene_locus related to this paper: idesa-peth

Title : Bioluminescence-based high-throughput screen identifies pharmacological agents that target neurotransmitter signaling in small cell lung carcinoma - Improgo_2011_PLoS.One_6_e24132
Author(s) : Improgo MR , Johnson CW , Tapper AR , Gardner PD
Ref : PLoS ONE , 6 :e24132 , 2011
Abstract : BACKGROUND: Frontline treatment of small cell lung carcinoma (SCLC) relies heavily on chemotherapeutic agents and radiation therapy. Though SCLC patients respond well to initial cycles of chemotherapy, they eventually develop resistance. Identification of novel therapies against SCLC is therefore imperative. METHODS AND FINDINGS: We have designed a bioluminescence-based cell viability assay for high-throughput screening of anti-SCLC agents. The assay was first validated via standard pharmacological agents and RNA interference using two human SCLC cell lines. We then utilized the assay in a high-throughput screen using the LOPAC(1280) compound library. The screening identified several drugs that target classic cancer signaling pathways as well as neuroendocrine markers in SCLC. In particular, perturbation of dopaminergic and serotonergic signaling inhibits SCLC cell viability.
CONCLUSIONS: The convergence of our pharmacological data with key SCLC pathway components reiterates the importance of neurotransmitter signaling in SCLC etiology and points to possible leads for drug development.
ESTHER : Improgo_2011_PLoS.One_6_e24132
PubMedSearch : Improgo_2011_PLoS.One_6_e24132
PubMedID: 21931655