| Structural highlights
Function
[KATG2_MAGO7] Bifunctional enzyme with both catalase and broad-spectrum peroxidase activity. Confers resistance to H(2)O(2) in hyphae. May play an antioxidative role in fungal defense against the host-produced H(2)O(2) (oxidative burst) at the early stage of plant infection.[1] [2]
Publication Abstract from PubMed
CatalaseAperoxidases (KatGs) are bifunctional heme enzymes widely spread in archaea, bacteria and lower eukaryotes. Here we present the first crystal structure (1.55 A resolution) of an eukaryotic KatG, the extracellular or secreted enzyme from the phytopathogenic fungus Magnaporthe grisea. The heme cavity of the homodimeric enzyme is similar to prokaryotic KatGs including the unique distal (+)MetATyrATrp adduct (where the Trp is further modified by a peroxidation) and its associated mobile arginine. The structure also revealed several conspicuous peculiarities that are fully conserved in all secreted eukaryotic KatGs. Peculiarities include the wrapping at the dimer interface of the N-terminal elongations from the two subunits and cysteine residues that crosslink the two subunits. Differential scanning calorimetry, temperature- and urea-mediated unfolding followed by UVAVis, circular dichroism and fluorescence spectroscopy combined with site-directed mutagenesis demonstrated that secreted eukaryotic KatGs have a significantly higher conformational stability as well as a different unfolding pattern compared to intracellular eukaryotic and prokaryotic catalase-peroxidases. We discuss these properties with respect to the structure as well as the postulated roles of this metalloenzyme in host-pathogen interactions.
High conformational stability of secreted eukaryotic catalase-peroxidases -answers from first crystal structure and unfolding studies.,Zamocky M, Garcia-Fernandez Q, Gasselhuber B, Jakopitsch C, Furtmuller PG, Loewen PC, Fita I, Obinger C, Carpena X J Biol Chem. 2012 Jul 27. PMID:22822072[3]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Tanabe S, Ishii-Minami N, Saitoh K, Otake Y, Kaku H, Shibuya N, Nishizawa Y, Minami E. The role of catalase-peroxidase secreted by Magnaporthe oryzae during early infection of rice cells. Mol Plant Microbe Interact. 2011 Feb;24(2):163-71. doi: 10.1094/MPMI-07-10-0175. PMID:21043575 doi:10.1094/MPMI-07-10-0175
- ↑ Zamocky M, Droghetti E, Bellei M, Gasselhuber B, Pabst M, Furtmuller PG, Battistuzzi G, Smulevich G, Obinger C. Eukaryotic extracellular catalase-peroxidase from Magnaporthe grisea - Biophysical/chemical characterization of the first representative from a novel phytopathogenic KatG group. Biochimie. 2012 Mar;94(3):673-83. doi: 10.1016/j.biochi.2011.09.020. Epub 2011, Sep 29. PMID:21971530 doi:10.1016/j.biochi.2011.09.020
- ↑ Zamocky M, Garcia-Fernandez Q, Gasselhuber B, Jakopitsch C, Furtmuller PG, Loewen PC, Fita I, Obinger C, Carpena X. High conformational stability of secreted eukaryotic catalase-peroxidases -answers from first crystal structure and unfolding studies. J Biol Chem. 2012 Jul 27. PMID:22822072 doi:http://dx.doi.org/10.1074/jbc.M112.384271
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