Article

The putative protein methyltransferase LAE1 controls cellulase gene expression in Trichoderma reesei. Mol Microbiol

Institute of Chemical Engineering, University of Technology of Vienna, Gumpendorferstrasse 1a, A-1060 Vienna, Austria.
Molecular Microbiology (Impact Factor: 4.42). 05/2012; 84(6):1150-64. DOI: 10.1111/j.1365-2958.2012.08083.x
Source: PubMed

ABSTRACT

Trichoderma reesei is an industrial producer of enzymes that degrade lignocellulosic polysaccharides to soluble monomers, which can be fermented to biofuels. Here we show that the expression of genes for lignocellulose degradation are controlled by the orthologous T. reesei protein methyltransferase LAE1. In a lae1 deletion mutant we observed a complete loss of expression of all seven cellulases, auxiliary factors for cellulose degradation, β-glucosidases and xylanases were no longer expressed. Conversely, enhanced expression of lae1 resulted in significantly increased cellulase gene transcription. Lae1-modulated cellulase gene expression was dependent on the function of the general cellulase regulator XYR1, but also xyr1 expression was LAE1-dependent. LAE1 was also essential for conidiation of T. reesei. Chromatin immunoprecipitation followed by high-throughput sequencing ('ChIP-seq') showed that lae1 expression was not obviously correlated with H3K4 di- or trimethylation (indicative of active transcription) or H3K9 trimethylation (typical for heterochromatin regions) in CAZyme coding regions, suggesting that LAE1 does not affect CAZyme gene expression by directly modulating H3K4 or H3K9 methylation. Our data demonstrate that the putative protein methyltransferase LAE1 is essential for cellulase gene expression in T. reesei through mechanisms that remain to be identified.

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    • "In industry, the fungus Trichoderma reesei produces enzymes such as cellulases that are used to catabolize polysaccharides into products that are used in biofuel production (Seiboth et al. 2012 ). Importantly , lae1 is necessary for normal expression of cellulase as well as xylanase genes and concomitant enzymatic activity in T. reesei (Seiboth et al. 2012). "

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    • "In these cases we either employ bead-beating (T. reesei, Karimi-Aghcheh et al., 2013; Seiboth et al., 2012) or grinding under liquid nitrogen followed by native ChIP (L. maculans, Soyer et al., 2014). "
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    • "The deletion of lae1 results in the complete loss of induction in multiple cellulase, b-glucosidases and xylanases, while the overexpression of lae1 results in increased expression. Furthermore, expression of xyr1, encoding the main inducer of lignocellulolytic enzyme-encoding genes, was shown to be LAE1 dependent (Seiboth et al., 2012). Comparative studies of the influence of LaeA on lignocellulolytic enzyme production in Aspergilli and N. crassa have not been undertaken due to the absence of CAZyme gene clusters in the respective genomes. "
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