Improvement of ligninolytic properties in the hyper lignin-degrading fungus Phanerochaete sordida YK-624 using a novel gene promoter

Abstract

We identified a highly expressed protein (BUNA2) by two-dimensional gel electrophoresis from the hyper lignin-degrading fungus Phanerochaete sordida YK-624 under wood-rotting conditions. Partial amino acid sequences of BUNA2 were determined by LC-MS/MS analysis, and BUNA2 gene (bee2) and promoter region were PCR-cloned and sequenced. The bee2 promoter was used to drive the expression of the manganese peroxidase gene (mnp4) in P. sordida YK-624. Eighteen mnp4-expressing clones were obtained, with most showing higher ligninolytic activity and selectivity than wild-type YK-624. Examination of the ligninolytic properties of the most effective lignin-degrading transformant, BM-65, cultured on wood meal revealed that this strain exhibited higher lignin degradation and MnP activities than those of wild type. Transcriptional analysis confirmed the increased expression of recombinant mnp4 in the transformant. These results indicate that use of the bee2 promoter to drive the expression of ligninolytic enzymes may be an effective approach for improving the lignin-degrading properties of white-rot fungi.