4mih
From Proteopedia
Pyranose 2-oxidase from Phanerochaete chrysosporium, recombinant H158A mutant
Structural highlights
Function[P2OX_PHACH] Catalyzes the oxidation of various aldopyranoses and disaccharides on carbon-2 to the corresponding 2-keto sugars concomitant with the reduction of O(2) to H(2)O(2). Plays an important role in lignin degradation of wood rot fungi by supplying the essential cosubstrate H(2)O(2) for the ligninolytic peroxidases, lignin peroxidase and manganese-dependent peroxidase. The preferred substrate is D-glucose which is converted to 2-dehydro-D-glucose, an intermediate of a secondary metabolic pathway leading to the antibiotic cortalcerone. Acts also on D-xylose, together with D-glucose the major sugars derived from wood, on L-sorbose, D-galactose and 1,5-anhydroglucitol, a diagnostic marker of diabetes mellitus.[1] [2] Publication Abstract from PubMedThe flavin-dependent homotetrameric enzyme pyranose 2-oxidase (P2O) is found mostly, but not exclusively, in lignocellulose-degrading fungi where it catalyzes the oxidation of beta-d-glucose to the corresponding 2-keto sugar concomitantly with hydrogen peroxide formation during lignin solubilization. Here, we present crystal structures of P2O from the efficient lignocellulolytic basidiomycete Phanerochaete chrysosporium. Structures were determined of wild-type PcP2O from the natural fungal source, and two variants of recombinant full-length PcP2O, both in complex with the slow substrate 3-deoxy-3-fluoro-beta-d-glucose. The active sites in PcP2O and P2O from Trametes multicolor (TmP2O) are highly conserved with identical substrate binding. Our structural analysis suggests that the 17 degrees C higher melting temperature of PcP2O compared to TmP2O is due to an increased number of intersubunit salt bridges. The structure of recombinant PcP2O expressed with its natural N-terminal sequence, including a proposed propeptide segment, reveals that the first five residues of the propeptide intercalate at the interface between A and B subunits to form stabilizing, mainly hydrophobic, interactions. In the structure of mature PcP2O purified from the natural source, the propeptide segment in subunit A has been replaced by a nearby loop in the B subunit. We propose that the propeptide in subunit A stabilizes the A/B interface of essential dimers in the homotetramer and that, upon maturation, it is replaced by the loop in the B subunit to form the mature subunit interface. This would imply that the propeptide segment of PcP2O acts as an intramolecular chaperone for oligomerization at the A/B interface of the essential dimer. Crystal structures of pyranose 2-oxidase suggest that the N-terminus acts as a propeptide that assists in homotetramer assembly.,Hassan N, Tan TC, Spadiut O, Pisanelli I, Fusco L, Haltrich D, Peterbauer CK, Divne C FEBS Open Bio. 2013 Nov 5;3:496-504. PMID:24282677[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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