| 1. |
- Andreasson, Erik, et al.
(författare)
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The MAP kinase substrate MKS1 is a regulator of plant defence responces
- 2005
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Ingår i: EMBO Journal. - : Wiley. - 1460-2075 .- 0261-4189. ; 24:14, s. 2579-2589
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Tidskriftsartikel (refereegranskat)abstract
- Arabidopsis MAP kinase 4 (MPK4) functions as a regulator of pathogen defense responses, because it is required for both repression of salicylic acid (SA)-dependent resistance and for activation of jasmonate (JA)-dependent defense gene expression. To understand MPK4 signaling mechanisms, we used yeast two-hybrid screening to identify the MPK4 substrate MKS1. Analyses of transgenic plants and genome-wide transcript profiling indicated that MKS1 is required for full SA-dependent resistance in mpk4 mutants, and that overexpression of MKS1 in wild-type plants is sufficient to activate SA-dependent resistance, but does not interfere with induction of a defense gene by JA. Further yeast two-hybrid screening revealed that MKS1 interacts with the WRKY transcription factors WRKY25 and WRKY33. WRKY25 and WRKY33 were shown to be in vitro substrates of MPK4, and a wrky33 knockout mutant was found to exhibit increased expression of the SA-related defense gene PR1. MKS1 may therefore contribute to MPK4-regulated defense activation by coupling the kinase to specific WRKY transcription factors.
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| 2. |
- Ortiz, Roberto, et al.
(författare)
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Engineering of Cellobiose Dehydrogenases for Improved Glucose Sensitivity and Reduced Maltose Affinityydrogenases for Improved Glucose Sensitivity and Reduced Maltose Affinity
- 2017
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Ingår i: ChemElectroChem. - : Wiley. - 2196-0216. ; 4:4, s. 846-855
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Tidskriftsartikel (refereegranskat)abstract
- Cellobiose dehydrogenase (CDH) is a fungal extracellular flavocytochrome capable of direct electron transfer (DET). Unlike other CDHs, the pH optimum for CDHs from Corynascus thermophilus (CtCDH) and Humicola insolens (HiCDH) is close to the human physiological pH in blood (7.4). These are, therefore, interesting candidates for glucose measurements in human blood and the application in enzymatic fuel cells is, however, limited by their relatively low activity with this substrate. In this work, the substrate specificities of CtCDH and HiCDH have been altered by a single cysteine to tyrosine substitution in the active sites of CtCDH (position 291) and HiCDH (position 285), which resulted in improved kinetic constants with glucose while decreasing the activity with several disaccharides, including maltose. The DET properties of the generated CDH variants were tested in the absence and in the presence of substrates, on graphite electrodes and thiolic self-assembled monolayer (SAM)-modified Au electrodes. Seven different thiols with different spacer lengths were used, containing -COOH, -OH, and -NH2 end groups. The length and head functionality of the thiol govern the efficiency of the DET reaction and indicate different DET properties of CtCDH and HiCDH
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| 3. |
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| 4. |
- Schulz, Christopher, et al.
(författare)
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Enhancement of enzymatic activity and catalytic current of cellobiose dehydrogenase by calcium ions
- 2012
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Ingår i: Electrochemistry Communications. - : Elsevier BV. - 1388-2481. ; 17, s. 71-74
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Tidskriftsartikel (refereegranskat)abstract
- Cellobiose dehydrogenase (CDH) has recently become a redox enzyme at focus in bioelectrochemistry especially for the construction of sugar biosensors and biofuel cell anodes. The present study shows that an increase in the CaCl2 concentration to up to 100 mM led to an increase in the maximal catalytic current generated by two different Ascomycete and one Basidiomycete CDH immobilised on a spectroscopic graphite electrode. For the Ascomycete Myriococcum therrnophilum CDH the catalytic current was increased 5.1 fold, whereas Ascomycete Humicola insolens CDH showed a four-fold increase and Basidiomycete Phanerochaete chrysosporium CDH showed an increase by a factor of 2.4. On the other hand, the addition of a monovalent cation salt, KCl (up to 100 mM), to the buffers increased the catalytic currents only up to 2-fold for Myriococcum thermophilum CDH. Activity assays in solution with cyt c accepting solely the electrons from the CYTCDH domain also revealed an increased activity in the presence of CaCl2. Experiments with the isolated DHCDH domain from Humicola insolens have shown that the catalytic turnover is totally independent on the addition of KCl or CaCl2 to the solution. The results indicate a positive effect of metal cations, particularly Ca2+, on the electron transfer between the DHCDH and the CYTCDH domains or between the CYTCDH domain and the final electron acceptor, whereas the first hypothesis is favoured. These findings are of interest both for the construction of 3 rd generation biosensors and biofuel cell anodes, and also for a deeper understanding of the electron transfer mechanism in CDH. (C) 2012 Elsevier B.V. All rights reserved.
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