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Samaniego LVB, Higasi PMR, de Mello Capetti CC, Cortez AA, Pratavieira S, de Oliveira Arnoldi Pellegrini V, Dabul ANG, Segato F, Polikarpov I. Staphylococcus aureus microbial biofilms degradation using cellobiose dehydrogenase from Thermothelomyces thermophilus M77. Int J Biol Macromol 2023; 247:125822. [PMID: 37451383 DOI: 10.1016/j.ijbiomac.2023.125822] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 07/09/2023] [Accepted: 07/11/2023] [Indexed: 07/18/2023]
Abstract
This work reports biochemical characterization of Thermothelomyces thermophilus cellobiose dehydrogenase (TthCDHIIa) and its application as an antimicrobial and antibiofilm agent. We demonstrate that TthCDHIIa is thermostable in different ionic solutions and is capable of oxidizing multiple mono and oligosaccharide substrates and to continuously produce H2O2. Kinetics measurements depict the enzyme catalytic characteristics consistent with an Ascomycota class II CDH. Our structural analyses show that TthCDHIIa substrate binding pocket is spacious enough to accommodate larger cello and xylooligosaccharides. We also reveal that TthCDHIIa supplemented with cellobiose reduces the viability of S. aureus ATCC 25923 up to 32 % in a planktonic growth model and also inhibits its biofilm growth on 62.5 %. Furthermore, TthCDHIIa eradicates preformed S. aureus biofilms via H2O2 oxidative degradation of the biofilm matrix, making these bacteria considerably more susceptible to gentamicin and tetracycline.
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Affiliation(s)
| | - Paula Miwa Rabelo Higasi
- Sao Carlos Institute of Physics, University of Sao Paulo, 1100 João Dagnone Avenue, 13563-120 São Carlos, SP, Brazil
| | - Caio Cesar de Mello Capetti
- Sao Carlos Institute of Physics, University of Sao Paulo, 1100 João Dagnone Avenue, 13563-120 São Carlos, SP, Brazil
| | - Anelyse Abreu Cortez
- Sao Carlos Institute of Physics, University of Sao Paulo, 1100 João Dagnone Avenue, 13563-120 São Carlos, SP, Brazil
| | - Sebastião Pratavieira
- Sao Carlos Institute of Physics, University of Sao Paulo, 1100 João Dagnone Avenue, 13563-120 São Carlos, SP, Brazil
| | | | - Andrei Nicoli Gebieluca Dabul
- Sao Carlos Institute of Physics, University of Sao Paulo, 1100 João Dagnone Avenue, 13563-120 São Carlos, SP, Brazil
| | - Fernando Segato
- Lorena School of Engineering, University of Sao Paulo, Estrada Municipal do Campinho, 12602-810 Lorena, SP, Brazil
| | - Igor Polikarpov
- Sao Carlos Institute of Physics, University of Sao Paulo, 1100 João Dagnone Avenue, 13563-120 São Carlos, SP, Brazil.
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Puertas-Bartolomé M, Włodarczyk-Biegun MK, Del Campo A, Vázquez-Lasa B, San Román J. Development of bioactive catechol functionalized nanoparticles applicable for 3D bioprinting. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2021; 131:112515. [PMID: 34857294 DOI: 10.1016/j.msec.2021.112515] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 10/19/2021] [Accepted: 10/22/2021] [Indexed: 12/11/2022]
Abstract
Efficient wound treatments to target specific events in the healing process of chronic wounds constitute a significant aim in regenerative medicine. In this sense, nanomedicine can offer new opportunities to improve the effectiveness of existing wound therapies. The aim of this study was to develop catechol bearing polymeric nanoparticles (NPs) and to evaluate their potential in the field of wound healing. Thus, NPs wound healing promoting activities, potential for drug encapsulation and controlled release, and further incorporation in a hydrogel bioink formulation to fabricate cell-laden 3D scaffolds are studied. NPs with 2 and 29 M % catechol contents (named NP2 and NP29) were obtained by nanoprecipitation and presented hydrodynamic diameters of 100 and 75 nm respectively. These nanocarriers encapsulated the hydrophobic compound coumarin-6 with 70% encapsulation efficiency values. In cell culture studies, the NPs had a protective effect in RAW 264.7 macrophages against oxidative stress damage induced by radical oxygen species (ROS). They also presented a regulatory effect on the inflammatory response of stimulated macrophages and promoted upregulation of the vascular endothelial growth factor (VEGF) in fibroblasts and endothelial cells. In particular, NP29 were used in a hydrogel bioink formulation using carboxymethyl chitosan and hyaluronic acid as polymeric matrices. Using a reactive mixing bioprinting approach, NP-loaded hydrogel scaffolds with good structural integrity, shape fidelity and homogeneous NPs dispersion, were obtained. The in vitro catechol NPs release profile of the printed scaffolds revealed a sustained delivery. The bioprinted scaffolds supported viability and proliferation of encapsulated L929 fibroblasts over 14 days. We envision that the catechol functionalized NPs and resulting bioactive bioink presented in this work offer promising advantages for wound healing applications, as they: 1) support controlled release of bioactive catechol NPs to the wound site; 2) can incorporate additional therapeutic functions by co-encapsulating drugs; 3) can be printed into 3D scaffolds with tailored geometries based on patient requirements.
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Affiliation(s)
- María Puertas-Bartolomé
- Institute of Polymer Science and Technology, ICTP-CSIC, Juan de la Cierva 3, 28006 Madrid, Spain; CIBER's Bioengineering, Biomaterials and Nanomedicine, CIBER-BBN, Health Institute Carlos III, Monforte de Lemos 3-5, 28029 Madrid, Spain; INM - Leibniz Institute for New Materials, Campus D2 2, 66123 Saarbrücken, Germany
| | | | - Aránzazu Del Campo
- INM - Leibniz Institute for New Materials, Campus D2 2, 66123 Saarbrücken, Germany; Chemistry Department, Saarland University, 66123 Saarbrücken, Germany
| | - Blanca Vázquez-Lasa
- Institute of Polymer Science and Technology, ICTP-CSIC, Juan de la Cierva 3, 28006 Madrid, Spain; CIBER's Bioengineering, Biomaterials and Nanomedicine, CIBER-BBN, Health Institute Carlos III, Monforte de Lemos 3-5, 28029 Madrid, Spain.
| | - Julio San Román
- Institute of Polymer Science and Technology, ICTP-CSIC, Juan de la Cierva 3, 28006 Madrid, Spain; CIBER's Bioengineering, Biomaterials and Nanomedicine, CIBER-BBN, Health Institute Carlos III, Monforte de Lemos 3-5, 28029 Madrid, Spain
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3
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Priddy-Arrington TR, Ward MS, Edwards RE, Caldorera-Moore ME. Proactive biomaterials for chronic wound management and treatment. CURRENT OPINION IN BIOMEDICAL ENGINEERING 2021. [DOI: 10.1016/j.cobme.2021.100327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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4
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Johnson JB, Broszczak DA, Mani JS, Anesi J, Naiker M. A cut above the rest: oxidative stress in chronic wounds and the potential role of polyphenols as therapeutics. J Pharm Pharmacol 2021; 74:485-502. [PMID: 33822141 DOI: 10.1093/jpp/rgab038] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 02/11/2021] [Indexed: 12/15/2022]
Abstract
OBJECTIVES The pathophysiology of chronic wounds typically involves redox imbalance and inflammation pathway dysregulation, often with concomitant microbial infection. Endogenous antioxidants such as glutathione and tocopherols are notably reduced or absent, indicative of significant oxidative imbalance. However, emerging evidence suggests that polyphenols could be effective agents for the amelioration of this condition. This review aims to summarise the current state of knowledge surrounding redox imbalance in the chronic wound environment and the potential use of polyphenols for the treatment of chronic wounds. KEY FINDINGS Polyphenols provide a multi-faceted approach towards the treatment of chronic wounds. Firstly, their antioxidant activity allows direct neutralisation of harmful free radicals and reactive oxygen species, assisting in restoring redox balance. Upregulation of pro-healing and anti-inflammatory gene pathways and enzymes by specific polyphenols further acts to reduce redox imbalance and promote wound healing actions, such as proliferation, extracellular matrix deposition and tissue remodelling. Finally, many polyphenols possess antimicrobial activity, which can be beneficial for preventing or resolving infection of the wound site. SUMMARY Exploration of this diverse group of natural compounds may yield effective and economical options for the prevention or treatment of chronic wounds.
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Affiliation(s)
- Joel B Johnson
- School of Health, Medical and Applied Science, CQUniversity, Bruce Hwy, North Rockhampton, Queensland, Australia.,Centre for Indigenous Health Equity Research, CQUniversity, Bruce Hwy, North Rockhampton, Queensland, Australia
| | - Daniel A Broszczak
- School of Biomedical Sciences, Faculty of Health, Queensland University of Technology, Brisbane, Queensland, Australia.,Tissue Repair and Translational Physiology Program, Institute of Health and Biomedical Innovation, Queensland University of Technology, Kelvin Grove, Queensland, Australia
| | - Janice S Mani
- School of Health, Medical and Applied Science, CQUniversity, Bruce Hwy, North Rockhampton, Queensland, Australia.,Centre for Indigenous Health Equity Research, CQUniversity, Bruce Hwy, North Rockhampton, Queensland, Australia
| | - Jack Anesi
- School of Science, Psychology and Sport, Federation University Australia, Ballarat, Victoria, Australia
| | - Mani Naiker
- School of Health, Medical and Applied Science, CQUniversity, Bruce Hwy, North Rockhampton, Queensland, Australia.,Centre for Indigenous Health Equity Research, CQUniversity, Bruce Hwy, North Rockhampton, Queensland, Australia
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Cellobiose dehydrogenase. FLAVIN-DEPENDENT ENZYMES: MECHANISMS, STRUCTURES AND APPLICATIONS 2020; 47:457-489. [DOI: 10.1016/bs.enz.2020.06.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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Sulej J, Osińska-Jaroszuk M, Jaszek M, Grąz M, Kutkowska J, Pawlik A, Chudzik A, Bancerz R. Antimicrobial and antioxidative potential of free and immobilised cellobiose dehydrogenase isolated from wood degrading fungi. Fungal Biol 2019; 123:875-886. [DOI: 10.1016/j.funbio.2019.09.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Revised: 09/06/2019] [Accepted: 09/17/2019] [Indexed: 11/24/2022]
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Puertas-Bartolomé M, Benito-Garzón L, Fung S, Kohn J, Vázquez-Lasa B, San Román J. Bioadhesive functional hydrogels: Controlled release of catechol species with antioxidant and antiinflammatory behavior. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2019; 105:110040. [PMID: 31546368 DOI: 10.1016/j.msec.2019.110040] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Revised: 07/22/2019] [Accepted: 07/30/2019] [Indexed: 12/13/2022]
Abstract
Chronic wounds are particularly difficult to heal and constitute an important global health care problem. Some key factors that make chronic wounds challenging to heal are attributed to the incessant release of free radicals, which activate the inflammatory system and impair the repair of the wound. Intrinsic characteristics of hydrogels are beneficial for wound healing, but the effective control of free radical levels in the wound and subsequent inflammation is still a challenge. Catechol, the key molecule responsible for the mechanism of adhesion of mussels, has been proven to be an excellent radical scavenger and anti-inflammatory agent. Our approach in this work lies in the preparation of a hybrid system combining the beneficial properties of hydrogels and catechol for its application as a bioactive wound dressing to assist in the treatment of chronic wounds. The hydrogel backbone is obtained through a self-covalent crosslinking between chitosan (Ch) and oxidized hyaluronic acid (HAox) in the presence of a synthetic catechol terpolymer, which is subsequently coordinated to Fe to obtain an interpenetrated polymer network (IPN). The structural analysis, catechol release profiles, in vitro biological behavior and in vivo performance of the IPN are analyzed and compared with the semi-IPN (without Fe) and the Ch/HAox crosslinked hydrogels as controls. Catechol-containing hydrogels present high tissue adhesion strength under wet conditions, support growth, migration and proliferation of hBMSCs, protect cells against oxidative stress damage induce by ROS, and promote down-regulation of the pro-inflammatory cytokine IL-1β. Furthermore, in vivo experiments reveal their biocompatibility and stability, and histological studies indicate normal inflammatory responses and faster vascularization, highlighting the performance of the IPN system. The novel IPN design also allows for the in situ controlled and sustained delivery of catechol. Therefore, the developed IPN is a suitable ECM-mimic platform with high cell affinity and bioactive functionalities that, together with the controlled catechol release, will enhance the tissue regeneration process and has a great potential for its application as wound dressing.
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Affiliation(s)
- María Puertas-Bartolomé
- Institute of Polymer Science and Technology, ICTP-CSIC, Juan de la Cierva 3, 28006 Madrid, Spain; CIBER-BBN, Institute of Health Carlos III, Monforte de Lemos 3-5 (11), 28029 Madrid, Spain
| | | | - Stephanie Fung
- Rutgers University, New Jersey Center for Biomaterials, 08854 Piscataway, NJ, USA
| | - Joachim Kohn
- Rutgers University, New Jersey Center for Biomaterials, 08854 Piscataway, NJ, USA
| | - Blanca Vázquez-Lasa
- Institute of Polymer Science and Technology, ICTP-CSIC, Juan de la Cierva 3, 28006 Madrid, Spain; CIBER-BBN, Institute of Health Carlos III, Monforte de Lemos 3-5 (11), 28029 Madrid, Spain.
| | - Julio San Román
- Institute of Polymer Science and Technology, ICTP-CSIC, Juan de la Cierva 3, 28006 Madrid, Spain; CIBER-BBN, Institute of Health Carlos III, Monforte de Lemos 3-5 (11), 28029 Madrid, Spain
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8
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Guebitz GM, Nyanhongo GS. Enzymes as Green Catalysts and Interactive Biomolecules in Wound Dressing Hydrogels. Trends Biotechnol 2018; 36:1040-1053. [DOI: 10.1016/j.tibtech.2018.05.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 05/16/2018] [Accepted: 05/21/2018] [Indexed: 02/08/2023]
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9
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Puertas-Bartolomé M, Vázquez-Lasa B, San Román J. Bioactive and Bioadhesive Catechol Conjugated Polymers for Tissue Regeneration. Polymers (Basel) 2018; 10:polym10070768. [PMID: 30960693 PMCID: PMC6403640 DOI: 10.3390/polym10070768] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Revised: 07/03/2018] [Accepted: 07/11/2018] [Indexed: 01/12/2023] Open
Abstract
The effective treatment of chronic wounds constitutes one of the most common worldwide healthcare problem due to the presence of high levels of proteases, free radicals and exudates in the wound, which constantly activate the inflammatory system, avoiding tissue regeneration. In this study, we describe a multifunctional bioactive and resorbable membrane with in-built antioxidant agent catechol for the continuous quenching of free radicals as well as to control inflammatory response, helping to promote the wound-healing process. This natural polyphenol (catechol) is the key molecule responsible for the mechanism of adhesion of mussels providing also the functionalized polymer with bioadhesion in the moist environment of the human body. To reach that goal, synthesized statistical copolymers of N-vinylcaprolactam (V) and 2-hydroxyethyl methacrylate (H) have been conjugated with catechol bearing hydrocaffeic acid (HCA) molecules with high yields. The system has demonstrated good biocompatibility, a sustained antioxidant response, an anti-inflammatory effect, an ultraviolet (UV) screen, and bioadhesion to porcine skin, all of these been key features in the wound-healing process. Therefore, these novel mussel-inspired materials have an enormous potential for application and can act very positively, favoring and promoting the healing effect in chronic wounds.
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Affiliation(s)
- María Puertas-Bartolomé
- Institute of Polymer Science and Technology, ICTP-CSIC, Juan de la Cierva 3, 28006 Madrid, Spain.
- CIBER's Bioengineering, Biomaterials and Nanomedicine, CIBER-BBN, Health Institute Carlos III, C/Monforte de Lemos 3-5, Pabellón 11, 28029 Madrid, Spain.
| | - Blanca Vázquez-Lasa
- Institute of Polymer Science and Technology, ICTP-CSIC, Juan de la Cierva 3, 28006 Madrid, Spain.
- CIBER's Bioengineering, Biomaterials and Nanomedicine, CIBER-BBN, Health Institute Carlos III, C/Monforte de Lemos 3-5, Pabellón 11, 28029 Madrid, Spain.
| | - Julio San Román
- Institute of Polymer Science and Technology, ICTP-CSIC, Juan de la Cierva 3, 28006 Madrid, Spain.
- CIBER's Bioengineering, Biomaterials and Nanomedicine, CIBER-BBN, Health Institute Carlos III, C/Monforte de Lemos 3-5, Pabellón 11, 28029 Madrid, Spain.
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10
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Huber D, Grzelak A, Baumann M, Borth N, Schleining G, Nyanhongo GS, Guebitz GM. Anti-inflammatory and anti-oxidant properties of laccase-synthesized phenolic-O-carboxymethyl chitosan hydrogels. N Biotechnol 2018; 40:236-244. [DOI: 10.1016/j.nbt.2017.09.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 09/12/2017] [Accepted: 09/15/2017] [Indexed: 10/18/2022]
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12
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Characterization of Cellobiose Dehydrogenase from a Biotechnologically Important Cerrena unicolor Strain. Appl Biochem Biotechnol 2015; 176:1638-58. [PMID: 26003328 PMCID: PMC4515248 DOI: 10.1007/s12010-015-1667-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Accepted: 05/12/2015] [Indexed: 11/30/2022]
Abstract
Cellobiose dehydrogenase (CDH), a secreted flavocytochrome produced by a number of wood-degrading fungi, was detected in the culture supernatant of a biotechnologically important strain of Cerrena unicolor grown in a modified cellulose-based liquid medium. The enzyme was purified as two active fractions: CuCDH-FAD (flavin domain) (1.51-fold) with recovery of 8.35 % and CuCDH (flavo-heme enzyme) (21.21-fold) with recovery of 73.41 %. As CDH from other wood-rotting fungi, the intact form of cellobiose dehydrogenase of C. unicolor is a monomeric protein containing one flavin and one heme b with molecular mass 97 kDa and pI = 4.55. The enzyme is glycosylated (8.2 %) mainly with mannose and glucosamine residues. Moreover, the cellobiose dehydrogenase gene cdh1 and its corresponding cDNA from the fungus C. unicolor were isolated, cloned, and characterized. The 2316-bp full-length cDNA of cdh1 encoded a mature CDH protein containing 771 amino acids preceded by a signal peptide consisting of 18 amino acids. Moreover, both active fractions were characterized in terms of kinetics, temperature and pH optima, and antioxidant properties.
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Pascual A, Tan JPK, Yuen A, Chan JMW, Coady DJ, Mecerreyes D, Hedrick JL, Yang YY, Sardon H. Broad-Spectrum Antimicrobial Polycarbonate Hydrogels with Fast Degradability. Biomacromolecules 2015; 16:1169-78. [DOI: 10.1021/bm501836z] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- Ana Pascual
- POLYMAT, University of the Basque Country UPV/EHU Joxe Mari Korta Center, Avda. Tolosa
72, 20018 Donostia-San
Sebastián, Spain
| | - Jeremy P. K. Tan
- Institute of Bioengineering
and Nanotechnology, 31 Biopolis Way, Singapore 138669, Singapore
| | - Alex Yuen
- POLYMAT, University of the Basque Country UPV/EHU Joxe Mari Korta Center, Avda. Tolosa
72, 20018 Donostia-San
Sebastián, Spain
| | - Julian M. W. Chan
- IBM Almaden Research
Center, 650 Harry Road, San Jose, California 95120, United States
| | - Daniel J. Coady
- IBM Almaden Research
Center, 650 Harry Road, San Jose, California 95120, United States
| | - David Mecerreyes
- Ikerbasque, Basque
Foundation for Science, E-48011 Bilbao, Spain
| | - James L. Hedrick
- IBM Almaden Research
Center, 650 Harry Road, San Jose, California 95120, United States
| | - Yi Yan Yang
- Institute of Bioengineering
and Nanotechnology, 31 Biopolis Way, Singapore 138669, Singapore
| | - Haritz Sardon
- POLYMAT, University of the Basque Country UPV/EHU Joxe Mari Korta Center, Avda. Tolosa
72, 20018 Donostia-San
Sebastián, Spain
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Phenolic antioxidants and their role in quenching of reactive molecular species in the human skin injury. ACTA ACUST UNITED AC 2015. [DOI: 10.1002/lite.201400078] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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Sygmund C, Santner P, Krondorfer I, Peterbauer CK, Alcalde M, Nyanhongo GS, Guebitz GM, Ludwig R. Semi-rational engineering of cellobiose dehydrogenase for improved hydrogen peroxide production. Microb Cell Fact 2013; 12:38. [PMID: 23617537 PMCID: PMC3654988 DOI: 10.1186/1475-2859-12-38] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Accepted: 04/14/2013] [Indexed: 11/10/2022] Open
Abstract
Background The ability of fungal cellobiose dehydrogenase (CDH) to generate H2O2in-situ is highly interesting for biotechnological applications like cotton bleaching, laundry detergents or antimicrobial functionalization of medical devices. CDH’s ability to directly use polysaccharide derived mono- and oligosaccharides as substrates is a considerable advantage compared to other oxidases such as glucose oxidase which are limited to monosaccharides. However CDH’s low activity with oxygen as electron acceptor hampers its industrial use for H2O2 production. A CDH variant with increased oxygen reactivity is therefore of high importance for biotechnological application. Uniform expression levels and an easy to use screening assay is a necessity to facilitate screening for CDH variants with increased oxygen turnover. Results A uniform production and secretion of active Myriococcum thermophilum CDH was obtained by using Saccharomyces cerevisiae as expression host. It was found that the native secretory leader sequence of the cdh gene gives a 3 times higher expression than the prepro leader of the yeast α-mating factor. The homogeneity of the expression in 96-well deep-well plates was good (variation coefficient <15%). A high-throughput screening assay was developed to explore saturation mutagenesis libraries of cdh for improved H2O2 production. A 4.5-fold increase for variant N700S over the parent enzyme was found. For production, N700S was expressed in P. pastoris and purified to homogeneity. Characterization revealed that not only the kcat for oxygen turnover was increased in N700S (4.5-fold), but also substrate turnover. A 3-fold increase of the kcat for cellobiose with alternative electron acceptors indicates that mutation N700S influences the oxidative- and reductive FAD half-reaction. Conclusions Site-directed mutagenesis and directed evolution of CDH is simplified by the use of S. cerevisiae instead of the high-yield-host P. pastoris due to easier handling and higher transformation efficiencies with autonomous plasmids. Twelve clones which exhibited an increased H2O2 production in the subsequent screening were all found to carry the same amino acid exchange in the cdh gene (N700S). The sensitive location of the five targeted amino acid positions in the active site of CDH explains the high rate of variants with decreased or entirely abolished activity. The discovery of only one beneficial exchange indicates that a dehydrogenase’s oxygen turnover is a complex phenomenon and the increase therefore not an easy target for protein engineering.
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Affiliation(s)
- Christoph Sygmund
- Vienna Institute of Biotechnology, Department of Food Sciences and Technology, BOKU-University of Natural Resources and Life Sciences, Vienna, Austria
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