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Makkar S, Béguin M, Dissertori G, Flock J, Fuentes C, Gajewski J, Hrbacek J, McNamara K, Ritzer C, Rucinski A, Weber D, Lomax A, Winterhalter C. PO-1602 Image reconstruction using the PETITION PET scanner aimed at biologically guided proton therapy. Radiother Oncol 2022. [DOI: 10.1016/s0167-8140(22)03566-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Winterhalter C, Togno M, Nesteruk KP, Emert F, Psoroulas S, Vidal M, Meer D, Weber DC, Lomax A, Safai S. Faraday cup for commissioning and quality assurance for proton pencil beam scanning beams at conventional and ultra-high dose rates. Phys Med Biol 2021; 66. [PMID: 33906166 DOI: 10.1088/1361-6560/abfbf2] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 04/27/2021] [Indexed: 11/11/2022]
Abstract
Recently, proton therapy treatments delivered with ultra-high dose rates have been of high scientific interest, and the Faraday cup (FC) is a promising dosimetry tool for such experiments. Different institutes use different FC designs, and either a high voltage guard ring, or the combination of an electric and a magnetic field is employed to minimize the effect of secondary electrons. The authors first investigate these different approaches for beam energies of 70, 150, 230 and 250 MeV, magnetic fields between 0 and 24 mT and voltages between -1000 and 1000 V. When applying a magnetic field, the measured signal is independent of the guard ring voltage, indicating that this setting minimizes the effect of secondary electrons on the reading of the FC. Without magnetic field, applying the negative voltage however decreases the signal by an energy dependent factor up to 1.3% for the lowest energy tested and 0.4% for the highest energy, showing an energy dependent response. Next, the study demonstrates the application of the FC up to ultra-high dose rates. FC measurements with cyclotron currents up to 800 nA (dose rates of up to approximately 1000 Gy s-1) show that the FC is indeed dose rate independent. Then, the FC is applied to commission the primary gantry monitor for high dose rates. Finally, short-term reproducibility of the monitor calibration is quantified within single days, showing a standard deviation of 0.1% (one sigma). In conclusion, the FC is a promising, dose rate independent tool for dosimetry up to ultra-high dose rates. Caution is however necessary when using a FC without magnetic field, as a guard ring with high voltage alone can introduce an energy dependent signal offset.
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Affiliation(s)
- C Winterhalter
- Centre for Proton Therapy, Paul Scherrer Institute, Switzerland.,Physics Department, ETH Zurich, Switzerland
| | - M Togno
- Centre for Proton Therapy, Paul Scherrer Institute, Switzerland
| | - K P Nesteruk
- Centre for Proton Therapy, Paul Scherrer Institute, Switzerland
| | - F Emert
- Centre for Proton Therapy, Paul Scherrer Institute, Switzerland
| | - S Psoroulas
- Centre for Proton Therapy, Paul Scherrer Institute, Switzerland
| | - M Vidal
- Institut Mediterraneen de Protontherapie, Centre Antoine Lacassagne, Nice, France
| | - D Meer
- Centre for Proton Therapy, Paul Scherrer Institute, Switzerland
| | - D C Weber
- Centre for Proton Therapy, Paul Scherrer Institute, Switzerland.,Radiation Oncology Department of the University Hospital of Bern, Switzerland.,Radiation Oncology Department of the University Hospital of Zürich, Switzerland
| | - A Lomax
- Centre for Proton Therapy, Paul Scherrer Institute, Switzerland.,Physics Department, ETH Zurich, Switzerland
| | - S Safai
- Centre for Proton Therapy, Paul Scherrer Institute, Switzerland
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Würfel FM, Wirtz RM, Winterhalter C, De laco P, Rosati M, Veltrup E, Martoni AA, Würfel W, Zamagni C. HLA-J as a new predictive marker in breast cancer for neoadjuvant chemotherapy. Geburtshilfe Frauenheilkd 2020. [DOI: 10.1055/s-0040-1717881] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Affiliation(s)
| | - RM Wirtz
- Stratifyer Molecular Pathology GmbH
| | | | - P De laco
- Obstetrics & Gynaecology Unit, S.Orsola-Malpighi Hospital
| | - M Rosati
- Obstetrics & Gynaecology Unit, S.Orsola-Malpighi Hospital
| | | | - AA Martoni
- Obstetrics & Gynaecology Unit, S.Orsola-Malpighi Hospital
| | | | - C Zamagni
- Obstetrics & Gynaecology Unit, S.Orsola-Malpighi Hospital
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Würfel FM, Wirtz R, Winterhalter C, De laco P, Rosati M, Veltrup E, Martoni AA, Würfel W, Zamagni C. Dynamic changes of HLA-J expression during neoadjuvant treatment in ovarian cancer. Geburtshilfe Frauenheilkd 2020. [DOI: 10.1055/s-0040-1718199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Affiliation(s)
| | | | | | - P De laco
- Obstetrics & Gynaecology Unit, S.Orsola-Malpighi Hospital
| | - M Rosati
- Obstetrics & Gynaecology Unit, S.Orsola-Malpighi Hospital
| | | | - AA Martoni
- Obstetrics & Gynaecology Unit, S.Orsola-Malpighi Hospital
| | | | - C Zamagni
- Obstetrics & Gynaecology Unit, S.Orsola-Malpighi Hospital
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Grevillot L, Boersma DJ, Fuchs H, Aitkenhead A, Elia A, Bolsa M, Winterhalter C, Vidal M, Jan S, Pietrzyk U, Maigne L, Sarrut D. Technical Note: GATE‐RTion: a GATE/Geant4 release for clinical applications in scanned ion beam therapy. Med Phys 2020; 47:3675-3681. [DOI: 10.1002/mp.14242] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 04/15/2020] [Accepted: 05/03/2020] [Indexed: 11/09/2022] Open
Affiliation(s)
- L. Grevillot
- MedAustron Ion Therapy Center Marie Curie‐Straße 5A‐2700Wiener Neustadt Austria
| | - D. J. Boersma
- MedAustron Ion Therapy Center Marie Curie‐Straße 5A‐2700Wiener Neustadt Austria
- ACMIT Gmbh Viktor‐Kaplan‐Straße 2/1A‐2700Wiener Neustadt Austria
| | - H Fuchs
- MedAustron Ion Therapy Center Marie Curie‐Straße 5A‐2700Wiener Neustadt Austria
- Medical University of Vienna Vienna Austria
- Department of Radiation Therapy Medical University of Vienna/AKH Vienna Vienna Austria
| | - A. Aitkenhead
- Division of Cancer Sciences University of ManchesterManchester Cancer Research CentreThe Christie NHS Foundation Trust Manchester UK
| | - A. Elia
- MedAustron Ion Therapy Center Marie Curie‐Straße 5A‐2700Wiener Neustadt Austria
| | - M. Bolsa
- MedAustron Ion Therapy Center Marie Curie‐Straße 5A‐2700Wiener Neustadt Austria
| | - C. Winterhalter
- Division of Cancer Sciences University of ManchesterThe Christie NHS Foundation Trust Manchester UK
| | - M. Vidal
- Centre Antoine LACASSAGNE Université Côte d’Azur – Fédération Claude Lalanne Nice France
| | - S. Jan
- UMR BioMaps CEACNRSInsermUniversité Paris‐Saclay 4 place du Général Leclerc91401Orsay France
| | | | - L. Maigne
- Université Clermont AuvergneCNRS/IN2P3Laboratoire de Physique de Clermont, UMR6533 4 avenue Blaise Pascal TSA 60026 CS60026 63178Aubière cedex France
| | - D. Sarrut
- Université de LyonCREATISCNRS UMR5220Inserm U1044INSA‐LyonUniversité Lyon 1 Lyon France
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Winterhalter C, Meier G, Oxley D, Weber D, Lomax A, Safai S. PO-0931 Application of a thin, energy-layer specific multi-leaf collimator for proton pencil beam scanning. Radiother Oncol 2019. [DOI: 10.1016/s0167-8140(19)31351-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Winterhalter C, Fura E, Tian Y, Aitkenhead A, Bolsi A, Dieterle M, Fredh A, Meier G, Oxley D, Siewert D, Weber DC, Lomax A, Safai S. Validating a Monte Carlo approach to absolute dose quality assurance for proton pencil beam scanning. ACTA ACUST UNITED AC 2018; 63:175001. [DOI: 10.1088/1361-6560/aad3ae] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Fredh A, Winterhalter C, Fura E, Bolsi A, Safai S, Weber D, Lomax A. EP-1815: Comparison of independent Monte Carlo calculations with measurements of spot scanned proton fields. Radiother Oncol 2018. [DOI: 10.1016/s0167-8140(18)32124-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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Winterhalter C, Lomax A, Oxley D, Weber DC, Safai S. A study of lateral fall-off (penumbra) optimisation for pencil beam scanning (PBS) proton therapy. Phys Med Biol 2018; 63:025022. [PMID: 29324441 DOI: 10.1088/1361-6560/aaa2ad] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The lateral fall-off is crucial for sparing organs at risk in proton therapy. It is therefore of high importance to minimize the penumbra for pencil beam scanning (PBS). Three optimisation approaches are investigated: edge-collimated uniformly weighted spots (collimation), pencil beam optimisation of uncollimated pencil beams (edge-enhancement) and the optimisation of edge collimated pencil beams (collimated edge-enhancement). To deliver energies below 70 MeV, these strategies are evaluated in combination with the following pre-absorber methods: field specific fixed thickness pre-absorption (fixed), range specific, fixed thickness pre-absorption (automatic) and range specific, variable thickness pre-absorption (variable). All techniques are evaluated by Monte Carlo simulated square fields in a water tank. For a typical air gap of 10 cm, without pre-absorber collimation reduces the penumbra only for water equivalent ranges between 4-11 cm by up to 2.2 mm. The sharpest lateral fall-off is achieved through collimated edge-enhancement, which lowers the penumbra down to 2.8 mm. When using a pre-absorber, the sharpest fall-offs are obtained when combining collimated edge-enhancement with a variable pre-absorber. For edge-enhancement and large air gaps, it is crucial to minimize the amount of material in the beam. For small air gaps however, the superior phase space of higher energetic beams can be employed when more material is used. In conclusion, collimated edge-enhancement combined with the variable pre-absorber is the recommended setting to minimize the lateral penumbra for PBS. Without collimator, it would be favourable to use a variable pre-absorber for large air gaps and an automatic pre-absorber for small air gaps.
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Affiliation(s)
- C Winterhalter
- Centre for Proton Therapy, Paul Scherrer Institute, 5232 Villigen, Switzerland
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Winterhalter C, Nicolle R, Louis A, To C, Radvanyi F, Elati M. Pepper: cytoscape app for protein complex expansion using protein-protein interaction networks. ACTA ACUST UNITED AC 2014; 30:3419-20. [PMID: 25138169 PMCID: PMC4816032 DOI: 10.1093/bioinformatics/btu517] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
We introduce Pepper (Protein complex Expansion using Protein–Protein intERactions), a Cytoscape app designed to identify protein complexes as densely connected subnetworks from seed lists of proteins derived from proteomic studies. Pepper identifies connected subgraph by using multi-objective optimization involving two functions: (i) the coverage, a solution must contain as many proteins from the seed as possible, (ii) the density, the proteins of a solution must be as connected as possible, using only interactions from a proteome-wide interaction network. Comparisons based on gold standard yeast and human datasets showed Pepper’s integrative approach as superior to standard protein complex discovery methods. The visualization and interpretation of the results are facilitated by an automated post-processing pipeline based on topological analysis and data integration about the predicted complex proteins. Pepper is a user-friendly tool that can be used to analyse any list of proteins. Availability: Pepper is available from the Cytoscape plug-in manager or online (http://apps.cytoscape.org/apps/pepper) and released under GNU General Public License version 3. Contact: mohamed.elati@issb.genopole.fr Supplementary information:Supplementary data are available at Bioinformatics online.
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Affiliation(s)
- C Winterhalter
- iSSB, CNRS, University of Evry, Genopole, 5 rue H. Desbruères, 91030 Evry Cedex, France, School of Computing Science, Newcastle University, Newcastle NE1 7RU, UK and UMR 144 CNRS/Institut Curie, 26 rue d'Ulm, Paris, 75248 cedex 05, France iSSB, CNRS, University of Evry, Genopole, 5 rue H. Desbruères, 91030 Evry Cedex, France, School of Computing Science, Newcastle University, Newcastle NE1 7RU, UK and UMR 144 CNRS/Institut Curie, 26 rue d'Ulm, Paris, 75248 cedex 05, France
| | - R Nicolle
- iSSB, CNRS, University of Evry, Genopole, 5 rue H. Desbruères, 91030 Evry Cedex, France, School of Computing Science, Newcastle University, Newcastle NE1 7RU, UK and UMR 144 CNRS/Institut Curie, 26 rue d'Ulm, Paris, 75248 cedex 05, France iSSB, CNRS, University of Evry, Genopole, 5 rue H. Desbruères, 91030 Evry Cedex, France, School of Computing Science, Newcastle University, Newcastle NE1 7RU, UK and UMR 144 CNRS/Institut Curie, 26 rue d'Ulm, Paris, 75248 cedex 05, France
| | - A Louis
- iSSB, CNRS, University of Evry, Genopole, 5 rue H. Desbruères, 91030 Evry Cedex, France, School of Computing Science, Newcastle University, Newcastle NE1 7RU, UK and UMR 144 CNRS/Institut Curie, 26 rue d'Ulm, Paris, 75248 cedex 05, France
| | - C To
- iSSB, CNRS, University of Evry, Genopole, 5 rue H. Desbruères, 91030 Evry Cedex, France, School of Computing Science, Newcastle University, Newcastle NE1 7RU, UK and UMR 144 CNRS/Institut Curie, 26 rue d'Ulm, Paris, 75248 cedex 05, France
| | - F Radvanyi
- iSSB, CNRS, University of Evry, Genopole, 5 rue H. Desbruères, 91030 Evry Cedex, France, School of Computing Science, Newcastle University, Newcastle NE1 7RU, UK and UMR 144 CNRS/Institut Curie, 26 rue d'Ulm, Paris, 75248 cedex 05, France
| | - M Elati
- iSSB, CNRS, University of Evry, Genopole, 5 rue H. Desbruères, 91030 Evry Cedex, France, School of Computing Science, Newcastle University, Newcastle NE1 7RU, UK and UMR 144 CNRS/Institut Curie, 26 rue d'Ulm, Paris, 75248 cedex 05, France
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Wong GK, Goldacker S, Winterhalter C, Grimbacher B, Chapel H, Lucas M, Alecsandru D, McEwen D, Quinti I, Martini H, Milito C, Schmidt RE, Ernst D, Espanol T, Vidaller A, Carbone J, Fernandez-Cruz E, Lougaris V, Plebani A, Kutukculer N, Gonzalez-Granado LI, Contreras R, Kiani-Alikhan S, Ibrahim MAA, Litzman J, Jones A, Gaspar HB, Hammarstrom L, Baumann U, Warnatz K, Huissoon AP. Outcomes of splenectomy in patients with common variable immunodeficiency (CVID): a survey of 45 patients. Clin Exp Immunol 2013; 172:63-72. [PMID: 23480186 DOI: 10.1111/cei.12039] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/16/2012] [Indexed: 01/29/2023] Open
Abstract
Splenectomy has been used in patients with common variable immunodeficiency disorders (CVID), mainly in the context of refractory autoimmune cytopenia and suspected lymphoma, but there are understandable concerns about the potential of compounding an existing immunodeficiency. With increasing use of rituximab as an alternative treatment for refractory autoimmune cytopenia, the role of splenectomy in CVID needs to be re-examined. This retrospective study provides the largest cohesive data set to date describing the outcome of splenectomy in 45 CVID patients in the past 40 years. Splenectomy proved to be an effective long-term treatment in 75% of CVID patients with autoimmune cytopenia, even in some cases when rituximab had failed. Splenectomy does not worsen mortality in CVID and adequate immunoglobulin replacement therapy appears to play a protective role in overwhelming post-splenectomy infections. Future trials comparing the effectiveness and safety of rituximab and splenectomy are needed to provide clearer guidance on the second-line management of autoimmune cytopenia in CVID.
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Affiliation(s)
- G K Wong
- West Midlands Primary Immunodeficiency centre, Birmingham Heartlands Hospital, UK
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Winterhalter C, Liebl W. Two Extremely Thermostable Xylanases of the Hyperthermophilic Bacterium Thermotoga maritima MSB8. Appl Environ Microbiol 2010; 61:1810-5. [PMID: 16535021 PMCID: PMC1388439 DOI: 10.1128/aem.61.5.1810-1815.1995] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
During growth with xylose or xylan as the source of carbon, xylanase production by Thermotoga maritima MSB8 was enhanced about 10-fold compared with growth with glucose or starch. Two extremely thermostable endoxylanases (1,4-(beta)-d-xylan-xylanohydrolase, EC 3.2.1.8), designated XynA and XynB, were identified and purified from cells of this organism. XynA and XynB occurred as proteins with apparent molecular masses of about 120 and 40 kDa, respectively, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Maximum activity at the optimal pH (pH 6.2 and pH 5.4 for XynA and XynB, respectively) was measured at about 92(deg)C for XynA (10-min assay) and at about 105(deg)C for XynB (5-min assay). XynB activity was stimulated twofold by the addition of 500 mM NaCl, while XynA displayed maximum activity without the addition of salt. Both xylanases were tolerant of relatively high salt concentrations. At 2 M (about 12% wt/vol) NaCl, XynA and XynB retained 49 and 65%, respectively, of their maximum activities. In contrast to XynB, XynA was able to adsorb to microcrystalline cellulose. Antibodies raised against a recombinant truncated XynA protein cross-reacted with XynB, indicating that the enzymes may have sequence or structural similarities. Part of the xylanase activity appeared to be associated with the outer membrane of T. maritima cells, since more than 40% of the total xylanase activity present in the crude cellular extract was found in the membrane fraction after high-speed centrifugation. Most of the membrane-bound activity appeared to be due to the 120-kDa xylanase XynA.
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Dassler T, Maier T, Winterhalter C, Böck A. Identification of a major facilitator protein from Escherichia coli involved in efflux of metabolites of the cysteine pathway. Mol Microbiol 2000; 36:1101-12. [PMID: 10844694 DOI: 10.1046/j.1365-2958.2000.01924.x] [Citation(s) in RCA: 115] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A chromosomal fragment has been identified in a gene bank from Escherichia coli, which augmented the yield of cysteine in an industrial production strain. Subcloning and genetic analysis showed that an open reading frame coding for a product of 299 amino acids (Orf299) was responsible. Orf299 was synthesized in the T7 polymerase/promoter system and exhibited the properties of an integral membrane protein. Mutational interruption of orf299 did not cause a distinct phenotype; however, transformants overexpressing orf299 had lost the ability to grow in minimal medium unless it was supplemented with a source of reduced sulphur compounds, and they excreted considerable amounts of cysteine and O-acetyl-L-serine, especially in the presence of thiosulphate. Most of the cysteine was found to be masked in 2-methyl-2,4-thiazolidinedicarboxylic acid. N-acetyl-L-serine was also present in the medium, but it is open to question whether it represents a primary excretion product. Measurement of the induction status of the cysteine regulon by means of a cysK'-'lacZ gene fusion demonstrated that the regulon is not induced upon growth in the presence of a poor sulphur source and that the introduction of a constitutive cysB allele alleviates this deficiency. The results indicate that orf299 codes for an export pump for different metabolites of the cysteine pathway. Its relation to other efflux systems and the physiological role are discussed.
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Affiliation(s)
- T Dassler
- Lehrstuhl für Mikrobiologie der Universität München, Maria-Ward-Strasse 1a, D-80638 München, Germany
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Ruile P, Winterhalter C, Liebl W. Isolation and analysis of a gene encoding alpha-glucuronidase, an enzyme with a novel primary structure involved in the breakdown of xylan. Mol Microbiol 1997; 23:267-79. [PMID: 9044261 DOI: 10.1046/j.1365-2958.1997.2011568.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
This is the first report describing the analysis of a gene encoding an alpha-glucuronidase, an enzyme essential for the complete breakdown of substituted xylans. A DNA fragment that carries the gene for alpha-glucuronidase was isolated from chromosomal DNA of the hyperthermophilic bacterium Thermotoga maritima MSB8. The alpha-glucuronidase gene (aguA) was identified and characterized with the aid of nucleotide sequence analysis, deletion experiments and expression studies in Escherichia coli, and the start of the coding region was defined by amino-terminal sequencing of the purified recombinant enzyme. The aguA gene encodes a 674-amino-acid, largely hydrophilic polypeptide with a calculated molecular mass of 78593 Da. The alpha-glucuronidase of T. maritima has a novel primary structure with no significant similarity to any other known amino acid sequence. The recombinant enzyme was purified to homogeneity as judged by SDS-PAGE. Gel filtration analysis at low salt concentrations revealed a high apparent molecular mass (> 630 kDa) for the recombinant enzyme, but the oligomeric structure changed upon variation of the ionic strength or the pH, yielding hexameric and/or dimeric forms which were also enzymatically active. The enzyme hydrolysed 2-O-(4-O-methyl-alpha-D-glucopyranosyluronic acid)-D-xylobiose (MeGlcAX2) to xylobiose and 4-O-methylglucuronic acid. The K(m) for MeGlcAX2 was 0.95 mM. The pH optimum was 6.3. Maximum activity was measured at 85 degrees C, about 25 degrees C or more above the values reported for all other alpha-glucuronidases known to date. When incubated at 55-75 degrees C, the enzyme suffered partial inactivation, but thereafter the residual activity remained nearly constant for several days.
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Affiliation(s)
- P Ruile
- Lehrstuhl für Mikrobiologie, Technische Universität München, Germany
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Winterhalter C, Heinrich P, Candussio A, Wich G, Liebl W. Identification of a novel cellulose-binding domain within the multidomain 120 kDa xylanase XynA of the hyperthermophilic bacterium Thermotoga maritima. Mol Microbiol 1995; 15:431-44. [PMID: 7783614 DOI: 10.1111/j.1365-2958.1995.tb02257.x] [Citation(s) in RCA: 109] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
A segment of Thermotoga maritima strain MSB8 chromosomal DNA was isolated which encodes an endo-1,4-beta-D-xylanase, and the nucleotide sequence of the xylanase gene, designated xynA, was determined. With a half-life of about 40 min at 90 degrees C at the optimal pH of 6.2, purified recombinant XynA is one of the most thermostable xylanases known. XynA is a 1059-amino-acid (approximately 120 kDa) modular enzyme composed of an N-terminal signal peptide and five domains, in the order A1-A2-B-C1-C2. By comparison with other xylanases of family 10 of glycosyl hydrolases, the central approximately 340-amino-acid part (domain B) of XynA represents the catalytic domain. The N-terminal approximately 150-amino-acid repeated domains (A1-A2) have no significant similarity to the C-terminal approximately 170-amino-acid repeated domains (C1-C2). Cellulose-binding studies with truncated XynA derivatives and hybrid proteins indicated that the C-terminal repeated domains mediate the binding of XynA to microcrystalline cellulose and that C2 alone can also promote cellulose binding. C1 and C2 did not share amino acid sequence similarity with any other known cellulose-binding domain (CBD) and thus are CBDs of a novel type. Structurally related protein segments which are probably also CBDs were found in other multidomain xylanolytic enzymes. Deletion of the N-terminal repeated domains or of all the non-catalytic domains resulted in substantially reduced thermostability while a truncated xylanase derivative lacking the C-terminal tandem repeat was as thermostable as the full-length enzyme.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- C Winterhalter
- Lehrstuhl für Mikrobiologie, Technische Universität, München, Germany
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