Repression of the expression of genes encoding xylanolytic enzymes in Aspergillus oryzae by introduction of multiple copies of the xynF1 promoter

A xylanase gene, xynF1, was cloned and characterized from a shoyu koji moul d Aspergillus oryzae KBN616. The xynF1 gene was found to be comprised of 14 84 bp with ten introns. The deduced amino acid sequence encodes a protein c onsisting of 327 amino acids (35,402 Da) which is very similar to the funga l family F xylanases such as Aspergillus nidulans XlnC, Aspergillus kawachi i XynA and Penicillium chrysogenum Xy1P. The intron/exon organization of xy nF1 is very similar to that of the fungal family F xylanase genes. Plasmid pXPR64, which contains 64 copies of the xynF1 promoter region (PxynF1) in t he same direction, was constructed and introduced into A. oryzae. This led to reduced expression of both xylanase and beta-xylosidase genes in the tra nsformants.