The cellobiose- and cellulose-responsive induction of the FIII-avicelase (cbhI), FII-carboxymethyl cellulase (cmc2), and FIa-xylanase (xynIa) genes is not regulated by XlnR in Aspergillus aculeatus, which suggests that this fungus possesses an unknown cellulase gene-activating pathway. To identify the regulatory factors involved in this pathway, we constructed a random insertional mutagenesis library using Agrobacterium tumefaciens-mediated transformation of A. aculeatus NCP2, which harbors a transcriptional fusion between the cbhI promoter (P ( CBHI )) and the orotidine 5'-phosphate decarboxylase gene (pyrG). Of the ~6,000 transformants screened, one 5-FOA-resistant transformant, S4-22, grew poorly on cellulose-containing media and exhibited reduced cellobiose-induced expression of cbhI. Southern blot analysis and nucleotide sequencing of the flanking regions of the T-DNA inserted in S4-22 indicated that the T-DNA was inserted within the coding region of a previously unreported Zn(II)(2)Cys(6)-transcription factor, which we designated the cellobiose response regulator (ClbR). The disruption of the clbR gene resulted in a significant reduction in the expression of cbhI and cmc2 in response to cellobiose and cellulose. Interestingly, the cellulose-responsive induction of FI-carboxymethyl cellulase (cmc1) and FIb-xylanase (xynIb) genes that are under the control of XlnR, was also reduced in the clbR-deficient mutant, but there was no effect on the induction of these genes in response to D-xylose or L-arabinose. These data demonstrate that ClbR participates in both XlnR-dependent and XlnR-independent cellobiose- and cellulose-responsive induction signaling pathways in A. aculeatus.

Two manganese peroxidases (MnPs), MnP1 and MnP2, and a laccase, Lac1, were purified from Trametes polyzona KU-RNW027. Both MnPs showed high stability in organic solvents which triggered their activities. Metal ions activated both MnPs at certain concentrations. The two MnPs and Lac1, played important roles in dye degradation and pharmaceutical products deactivation in a redox mediator-free system. They completely degraded Remazol brilliant blue (25 mg/L) in 10-30 min and showed high degradation activities to Remazol navy blue and Remazol brilliant yellow, while Lac1 could remove 75% of Remazol red. These three purified enzymes effectively deactivated tetracycline, doxycycline, amoxicillin, and ciprofloxacin. Optimal reaction conditions were 50 C and pH 4.5. The two MnPs were activated by organic solvents and metal ions, indicating the efficacy of using T. polyzona KU-RNW027 for bioremediation of aromatic compounds in environments polluted with organic solvents and metal ions with no need for redox mediator supplements.

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In the past decade, various transcriptional activators of cellulolytic enzyme genes have been identified in Ascomycete fungi. The regulatory system of cellulolytic enzymes is not only partially conserved, but also significantly diverse. For example, Trichoderma reesei has a system distinct from those of Aspergillus and Neurospora crassa-the former utilizes Xyr1 (the Aspergillus XlnR ortholog) as the major regulator of cellulolytic enzyme genes, while the latter uses CLR-2/ClrB/ManR orthologs. XlnR/Xyr1 and CLR-2/ClrB/ManR are evolutionarily distant from each other. Regulatory mechanisms that are controlled by CLR-2, ClrB, and ManR are also significantly different, although they are orthologous factors. Expression of clr-2 requires the activation of another transcription factor, CLR-1, by cellobiose, while CLR-2 is constitutively active for transactivation. By contrast, ClrB activation requires cellobiose. While ClrB mainly regulates cellulolytic genes, ManR is essential for the activation of not only cellulolytic but also mannanolytic enzyme genes. In this review, we summarize XlnR/Xyr1- and CLR-2/ClrB/ManR-dependent regulation in N. crassa, A. nidulans, A. oryzae, and T. reesei and emphasize the conservation and diversity of the regulatory systems for cellulolytic enzyme genes in these Ascomycete fungi. In addition, we discuss the role of McmA, another transcription factor that plays an important role in recruiting ClrB to the promoters in A. nidulans.