BIOCHEMICAL ANALYSIS OF THE PLEUROTUS OSTREATUS LIGNIN-MODIFYING ENZYME VERSATILE PEROXIDASE (VP1); THE MOST RUBUST ENZYME IN OXIDATION OF AROMATIC COMPOUNDS

Doriv Knop Dana Levinson Oded Yarden Yitzhak Hadar
Department of Plant Pathology and Microbiology, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel

Versatile peroxidases from white rot fungi (WRF) such as Pleurotus ostreatus have received much attention in recent years due to their flexible ability to oxidize both low and high redox potential compounds including lignin in both Mn2+- mediated and Mn2+- independent mode of actions (1). The VPs contain unique active sites which are responsible of direct oxidation of various aromatic compounds in addition to the well-known Mn2+ binding active site. In Mn2+ -amended glucose-peptone (GP) medium the expression level of the vp1 gene was extremely repressed. This seems to be a "biological contradiction", as Mn2+ is considered to be the best substrate of VPs. The aim of this study was to explore the oxidation mechanisms of aromatic compounds by VP1 and its function under Mn2+-deficiency. We show that in Mn2+-deficient GP medium VP1 (encoded by vp1) has a key and non-redundant function (2). To better understand the degradation mechanisms, we purified and characterized VP1. While the pH optimum for Mn2+ oxidation is 5, the optimum pH of direct oxidation was found to be 3-3.5. Indeed, effective -independent in vivo decoloriszation occurred only under acidic conditions. In addition, competitive inhibition was found to occur between Mn2+ and direct oxidations, thus shedding light on the aforementioned "biological contradiction". Moreover, LC-MS determined that the mechanisms of oxidation are affected by the presence of Mn2+ and pH level.

  1. Knop D, Yarden O, Hadar Y. 2015. The ligninolytic peroxidases in the genus Pleurotus: divergence in activities, expression, and potential applications. Applied Microbiology and Biotechnology 99:1025-1038.
  2. Knop D, Ben-Ari J, Salame TM, Levinson D, Yarden O, Hadar Y. 2014. Mn2+-deficiency reveals a key role for the Pleurotus ostreatus versatile peroxidase (VP4) in oxidation of aromatic compounds. Applied Microbiology and Biotechnology 98:6795-6804.








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