Analysis of Light- and Carbon-Specific Transcriptomes Implicates a Class of G-Protein-Coupled Receptors in Cellulose Sensing

Abstract

In fungi, most metabolic processes are subject to regulation by light. For Trichoderma reesei, light-dependent regulation of cellulase gene expression is specifically shown. Therefore, we intended to unravel the relationship between regulation of enzymes by the carbon source and regulation of enzymes by light. Our two-dimensional analysis included inducing and repressing carbon sources which we used to compare light-specific regulation to dark-specific regulation and to rule out effects specific for a single carbon source. We found close connections with respect to gene regulation as well as significant differences in dealing with carbon in the environment in light and darkness. Moreover, our analyses showed an intricate regulation mechanism for substrate degradation potentially involving surface sensing and provide a basis for knowledge-based screening for strain improvement.

A CRE1- regulated cluster is responsible for light dependent production of dihydrotrichotetronin in Trichoderma reesei

“…We found that the photoreceptors BLR1 and BLR2 negatively regulate the genes of this cluster, while ENV1 exerts positive regulation (Figure A in S3 File ; [ 10 ]), hence suggesting that this cluster is important for photoadaptation [ 49 – 51 ]. Evaluation of transcriptome data from growth of the wild-type on different carbon sources revealed that the cluster is upregulated upon growth on cellulose and on glucose, but only very low transcript levels are present on glycerol, lactose and sophorose (GSE81365) [ 9 ], which is in agreement with detection of a product of the cluster upon growth on glucose as reported previously [ 41 ]. The regulation of the SOR cluster genes by components of the heterotrimeric G-protein pathway as found upon re-analysis of transcriptome data from strains lacking the G-protein beta and gamma subunits or a phosducin (GSE27581) [ 8 ] supports a connection to nutrient sensing.…”

“…Our previous data showed that this cluster 1 ( S2 File ) overlaps with a light dependently regulated cluster on cellulose [ 9 ]. Accordingly, (direct or indirect) regulation of the cluster by CRE1 was negative in light and positive in darkness ( Fig 1B ).…”

Broad substrate-specific phosphorylation events are associated with the initial stage of plant cell wall recognition inNeurospora crassa

“…Even though Neurospora was grown under constant light conditions for the present study, the data reveal abundant phosphorylations present in clock components. Crosstalk between gene regulation in response to different nutritional conditions and the light response pathway is extensive (Schmoll, 2018; Stappler et al, 2017) and was also shown in N. crassa (Sancar et al, 2012; Schmoll et al, 2012). FREQUENCY (FRQ; NCU02265) is a key component of the Neurospora circadian clock, allowing precise daily control of several processes, including metabolism (Hurley et al, 2016; Montenegro-Montero et al, 2015).…”

SUB1 has photoreceptor dependent and independent functions in sexual development and secondary metabolism in Trichoderma reesei

“…Transcript abundance of sub1 is more than twofold decreased on lack of blr1 and blr2 in light on growth on cellulose, while unaltered in darkness. The strong upregulation of transcript levels of bcltf1 (Schumacher et al ., ), the B. cinerea homologue of sub1 , was not seen in T. reesei , where only a moderate elevation of less than twofold was observed on growth on cellulose or glucose (Tisch and Schmoll, ; Stappler et al ., ). Phylogenetic analysis of SUB1 confirmed that it is a homologue of N. crassa SUB‐1 and A. nidulans NsdD (Supporting Information Fig.…”