TITLE:
Factors Affecting the Induction of Lignin Peroxidase in Manganese-Deficient Cultures of the White Rot Fungus Phanerochaete chrysosporium
AUTHORS:
Avi Matityahu, Aya Sitruk, Yitzhak Hadar, Paula A. Belinky
KEYWORDS:
ROS, GLOX, MnSOD, PKC, lip-H2 Induction
JOURNAL NAME:
Advances in Microbiology,
Vol.5 No.2,
February
10,
2015
ABSTRACT: The lignin peroxidase (LIP) production and regulation, in manganese ions (Mn2+) deficient cultures of the white rot fungus Phanerochaete chrysosporium, is still not clearly understood. Mn2+ deficiency is correlated to low levels of manganese containing superoxide dismutase (MnSOD). In this work, we show that despite the low activity level of MnSOD in Mn2+-deficient cultures, the presence of H2O2 is essential for the expression of the lip-H2 gene, which encodes for the major LIP isoenzyme produced (LIP-H2). Thus, the H2O2 present in Mn2+-deficient cultures is probably produced by other mechanisms rather than dismutation of superoxide ions by MnSOD. Glyoxal oxidase gene (glox) expression was significantly higher than MnSOD (MnSOD1) and cellobiose dehydrogenase (cdh1) expression in Mn2+-deficient cultures, indicating its clear involvement in H2O2 production in those cultures. Glyoxal oxidase may compensate the absence of MnSOD activity in Mn2+-deficient cultures. The high levels of reactive oxygen species (ROS) needed for the enhancement of LIP expression in Mn2+-deficient cultures were not directly correlated to the protein kinase C (PKC) activity involved in signal transduction pathway. High level of oxidative stress was observed in MnSOD silenced mutants, grown in the presence of Mn2+, indicating that oxidative stress in Mn2+-deficient cultures was caused by low levels of MnSOD rather than the deficiency in Mn2+. The results of this work can further contribute to the understanding of LIP regulation in Mn2+-deficient cultures.