Dipeptidyl peptidase IV is involved in the cellulose-responsive induction of cellulose biomass-degrading enzyme genes in <i>Aspergillus aculeatus</i>

<p>We screened for factors involved in the cellulose-responsive induction of cellulose biomass-degrading enzyme genes from approximately 12,000 <i>Aspergillus aculeatus</i> T-DNA insertion mutants harboring a transcriptional fusion between the FIII-avicelase gene (<i>cbhI</i>) promoter and the orotidine 5′-monophosphate decarboxylase gene. Analysis of 5-fluoroorodic acid (5-FOA) sensitivity, cellulose utilization, and <i>cbhI</i> expression of the mutants revealed that a mutant harboring T-DNA at the dipeptidyl peptidase IV (<i>dppIV</i>) locus had acquired 5-FOA resistance and was deficient in cellulose utilization and <i>cbhI</i> expression. The deletion of <i>dppIV</i> resulted in a significant reduction in the cellulose-responsive expression of both <i>cbhI</i> as well as genes controlled by XlnR-independent and XlnR-dependent signaling pathways at an early phase in <i>A. aculeatus</i>. In contrast, the <i>dppIV</i> deletion did not affect the xylose-responsive expression of genes under the control of XlnR. These results demonstrate that DppIV participates in cellulose-responsive induction in <i>A. aculeatus</i>.</p> <p>Dashed lines with arrows indicate putative signaling pathways.</p