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M cm A ‐dependent and ‐independent regulatory systems governing expression of C lr B ‐regulated cellulase and hemicellulase genes in A spergillus nidulans
Author(s) -
Li Nuo,
Kunitake Emi,
Aoyama Miki,
Ogawa Masahiro,
Kanamaru Kyoko,
Kimura Makoto,
Koyama Yasuji,
Kobayashi Tetsuo
Publication year - 2016
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.13493
Subject(s) - cellulase , biology , gene , gene expression , mutant , cellulose , biochemistry
Summary Fungal cellulolytic and hemicellulolytic enzymes are promising tools for industrial hydrolysis of cellulosic biomass; however, the regulatory network underlying their production is not well understood. The recent discovery of the transcriptional activators ClrB and McmA in Aspergillus nidulans implied a novel regulatory mechanism driven by their interaction, experimental evidence for which was obtained from transcriptional and DNA‐binding analyses in this study. It was found that ClrB was essential for induced expression of all the genes examined in this study, while McmA dependency of their expression was gene‐dependent. DNA‐binding studies revealed McmA assisted in the recruitment of ClrB to the cellulose‐responsive element (CeRE) in the promoters of eglA and eglB , expression of which was significantly reduced in the mcmA mutant. The CCG triplet within the CeRE served as the recognition sequence for the ClrB monomer. In contrast, ClrB did not require McmA for binding as a homodimer to the CGGN 8 CCG sequences in the promoter of mndB , expression of which was affected less in the mcmA mutant than in all other examined genes. Thus, there are two types of ClrB‐mediated regulation: McmA‐assisted and McmA‐independent. This novel McmA–ClrB synergistic system provides new insights into the complex regulatory network involved in cellulase and hemicellulase production.