Dehydrogenase GRD1 Represents a Novel Component of the Cellulase Regulon in Trichoderma reesei (Hypocrea jecorina)

Abstract

Trichoderma reesei (Hypocrea jecorina) is nowadays the most important industrial producer of cellulase and hemicellulase enzymes, which are used for pretreatment of cellulosic biomass for biofuel production. In this study, we introduce a novel component, GRD1 (glucose-ribitol dehydrogenase 1), which shows enzymatic activity on cellobiose and positively influences cellulase gene transcription, expression, and extracellular endo-1,4-␤-D-glucanase activity. grd1 is differentially transcribed upon growth on cellulose and the induction of cellulase gene expression by sophorose. The transcription of grd1 is coregulated with that of cel7a (cbh1) under inducing conditions. GRD1 is further involved in carbon source utilization on several carbon sources, such as those involved in lactose and D-galactose catabolism, in several cases in a light-dependent manner. We conclude that GRD1 represents a novel enhancer of cellulase gene expression, which by coregulation with the major cellulase may act via optimization of inducing mechanisms.

Roles of Protein Kinase A and Adenylate Cyclase in Light-Modulated Cellulase Regulation in Trichoderma reesei

“…Interestingly, we also found light-modulated cellulase gene expression on lactose, but we were surprised that the effect of light is reversed compared to that with cellulose, since on lactose darkness is beneficial for high levels of cellulase gene transcripts. A similar phenomenon was seen for induction of cellulase gene transcription by sophorose (56). Consequently the assessment of the significance of a given nutrient signal with respect to its relevance in light and darkness can also be observed on lactose.…”

Regulation of Glycoside Hydrolase Expression in Trichoderma

“…Studies on transcription and secreted cellulase activity under different conditions were the basis for the conclusion that regulation of cellulase gene expression occurs at the level of transcription (El-Gogary et al, 1989;Messner et al, 1991;Morawetz et al, 1992). However, until recently, an influence of light or the light response machinery was not considered and a study on the short chain dehydrogenase GRD1, which is co-regulated with cbh1, revealed differences in transcript levels, protein abundance and activity (Schuster et al, 2011). Discrepancies were further observed for regulation of cellulase transcripts by the photoreceptors BLR1, BLR1 and ENV1, which act positively on cellulase transcription (Castellanos et al, 2010;Schmoll et al, 2005), while in a fermentor cultivation it was observed that cellulase activity of some of the respective deletion strains even increases (Gyalai-Korpos et al, 2010).…”

“…Light can have both positive and negative effect on growth depending on the carbon source (Schuster et al, 2007). Cellulase gene expression was found to be modulated by light on different carbon sources (Schmoll et al, 2005;Schuster et al, 2011Schuster et al, , 2012 including cellulose, lactose and sophorose.…”

10 Genomics Analysis of Biocontrol Species and Industrial Enzyme Producers from the Genus Trichoderma

“…A study on the function of a novel dehydrogenase revealed discrepancies between regulation of cellulase transcription, abundance of CBH1 in the culture medium, and activity (Schuster et al 2011). Studies investigating the effect of photoreceptors on cellulase gene expression in T. reesei (Gyalai-Korpos et al 2010) and N. crassa indicated that at least with respect to light response, posttranslational regulation of cellulase gene expression is a conserved phenomenon.…”

“…Alternatively, prior to the availability of fully sequenced genomes, methods for genome-wide cDNA subtraction and analysis were applied. Although these analyses only yielded a small number of regulated genes compared to microarrays, they nevertheless revealed involvement of novel genes (Mukherjee et al 2007;Schmoll et al 2004;Schuster et al 2011). A medium-scale approach for transcript analysis in multiple samples was provided by the TRAC (transcript analysis with the aid of affinity capture) system, which allows for simultaneous analysis of 96 samples for around 30 genes (Kataja et al 2006;Rautio et al 2006Rautio et al , 2007.…”