||Conservation and diversity of the regulators of cellulolytic enzyme genes in ascomycete fungi
Kunitake, EmiKobayashi, Tetsuo
958 , 2017-12 , Springer
In the past decade, various transcriptional activatorsof cellulolytic enzyme genes have been identifedin Ascomycete fungi. The regulatory system of cellulolyticenzymes is not only partially conserved, but also signifcantlydiverse. For example, Trichoderma reesei has asystem distinct from those of Aspergillus and Neurosporacrassa—the former utilizes Xyr1 (the Aspergillus XlnRortholog) as the major regulator of cellulolytic enzymegenes, while the latter uses CLR-2/ClrB/ManR orthologs.XlnR/Xyr1 and CLR-2/ClrB/ManR are evolutionarily distantfrom each other. Regulatory mechanisms that are controlledby CLR-2, ClrB, and ManR are also signifcantlydifferent, although they are orthologous factors. Expressionof clr-2 requires the activation of another transcription factor,CLR-1, by cellobiose, while CLR-2 is constitutivelyactive for transactivation. By contrast, ClrB activationrequires cellobiose. While ClrB mainly regulates cellulolyticgenes, ManR is essential for the activation of notonly cellulolytic but also mannanolytic enzyme genes. Inthis 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 anddiversity of the regulatory systems for cellulolytic enzyme genes in these Ascomycete fungi. In addition, we discussthe role of McmA, another transcription factor that playsan important role in recruiting ClrB to the promoters in A.nidulans.