English   español  
Por favor, use este identificador para citar o enlazar a este item: http://hdl.handle.net/10261/111163
logo share SHARE logo core CORE   Add this article to your Mendeley library MendeleyBASE

Visualizar otros formatos: MARC | Dublin Core | RDF | ORE | MODS | METS | DIDL
Exportar a otros formatos:

Two alternative substrate paths for compound I formation and reduction in catalase-peroxidase KatG from Burkholderia pseudomallei

AutorDeemagarn, Taweewat; Wiseman, Ben; Carpena, Xavi ; Ivancich, Anabella; Fita, Ignacio ; Loewen, Peter C.
Palabras claveKatG
Electron paramagnetic resonance
Crystal structure
Fecha de publicación1-ene-2007
CitaciónProteins: Structure, Function and Genetics 66(1): 219-228 (2007)
ResumenFive residues in the multifunctional catalase-peroxidase KatG of Burkholderia, pesudomallei are essential for catalase, but not peroxidase, activity. Asp141 is the only one of these catalase-specific residues not related with the covalent adduct found in KatGs that when replaced with a nonacidic residue reduces catalase activity to 5% of native levels. Replacing the nearby catalytic residue Arg108 causes a reduction in catalase activity to 35% of native levels, whereas a variant with both Asp141 and Arg108 replaced exhibits near normal catalase activity (82% of native), suggesting a synergism in the roles of the two residues in support of catalase activity in the enzyme. Among the Asp141 variants, D141E is unique in retaining normal catalase activity but with modified kinetics, suggesting more favorable compound I formation and less favorable compound I reduction. The crystal structure of the D141E variant has been determined at 1.8-Å resolution, revealing that the carboxylate of Glu141 is moved only slightly compared with Asp141, but retains its hydrogen bond interaction with the main chain nitrogen of Ile237. In contrast, the low temperature ferric Electron Paramagnetic Resonance spectra of the D141A, R108A, and R108A/D141A variants are consistent with modifications of the water matrix and/or the relative positioning of the distal residue side chains. Such changes explain the reduction in catalase activity in all but the double variant R108A/ D141A. Two pathways of hydrogen bonded solvent lead from the entrance channel into the heme active site, one running between Asp141 and Arg108 and the second between Asp141 and the main chain atoms of residues 237-239. It is proposed that binding of substrate H2O2 to Asp141 and Arg108 controls H2O2 access to the heme active site, thereby modulating the catalase reaction. © 2006 Wiley-Liss, Inc.
Versión del editorhttp://dx.doi.org/10.1002/prot.21209
Identificadoresdoi: 10.1002/prot.21209
issn: 0887-3585
Aparece en las colecciones: (IBMB) Artículos
Ficheros en este ítem:
Fichero Descripción Tamaño Formato  
accesoRestringido.pdf15,38 kBAdobe PDFVista previa
Mostrar el registro completo

Artículos relacionados:

NOTA: Los ítems de Digital.CSIC están protegidos por copyright, con todos los derechos reservados, a menos que se indique lo contrario.