Mori Toshio, Koyama Genki, Kawagishi Hirokazu, Hirai Hirofumi
Faculty of Agriculture, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka, 422-8529, Japan.
Research Institute of Green Science and Technology, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka, 422-8529, Japan.
Curr Microbiol. 2016 Oct;73(4):512-8. doi: 10.1007/s00284-016-1089-6. Epub 2016 Jun 30.
We investigated the function of 1,4-benzoquinone reductase (BQR)- and homogentisate 1,2-dioxygenase (HGD)-like genes in wood degradation by Phanerochaete sordida YK-624, which exhibits high ligninolytic activity and selectivity. We determined homologous expression in the genomic and cDNA sequences of BQR- and HGD-like genes in P. sordida YK-624 (PsBQR and PsHGD). Both genes shared high homology (≥90 % amino acid sequence similarity) with the corresponding genes in Phanerochaete chrysosporium. These genes were co-transformed with a reporter gene into an uracil auxotrophic mutant of P. sordida YK-624. The PsBQR and PsHGD co-transformants exhibited lower holocellulolytic activity and higher ligninolytic selectivity than the control transformants. In liquid culture with vanillin, both co-transformants significantly accelerated vanillin degradation. Thus, we suggest that the rapid metabolism of low-molecular weight lignin fragments, due to the homologous expression of BQR- and HGD-like genes, affects quinone redox cycling to produce hydroxyl radicals, thereby decreasing holocellulose degradation and increasing ligninolytic selectivity.
我们研究了1,4 - 苯醌还原酶（BQR）和尿黑酸1,2 - 双加氧酶（HGD）样基因在具有高木质素分解活性和选择性的黄孢原毛平革菌YK - 624木材降解中的作用。我们确定了黄孢原毛平革菌YK - 624（PsBQR和PsHGD）中BQR和HGD样基因在基因组和cDNA序列中的同源表达。这两个基因与黄孢原毛平革菌中的相应基因具有高度同源性（氨基酸序列相似性≥90%）。这些基因与一个报告基因共转化到黄孢原毛平革菌YK - 624的尿嘧啶营养缺陷型突变体中。与对照转化体相比，PsBQR和PsHGD共转化体表现出较低的全纤维素分解活性和较高的木质素分解选择性。在含有香草醛的液体培养中，两个共转化体均显著加速了香草醛的降解。因此，我们认为，由于BQR和HGD样基因的同源表达，低分子量木质素片段的快速代谢影响醌氧化还原循环以产生羟基自由基，从而减少全纤维素降解并提高木质素分解选择性。
