Role of Trichoderma reesei mitogen-activated protein kinases (MAPKs) in cellulase formation

Abstract

BackgroundDespite being the most important cellulase producer, the cellulase-regulating carbon source signal transduction processes in Trichoderma reesei are largely unknown. Elucidating these processes is the key for unveiling how external carbon sources regulate cellulase formation, and ultimately for the improvement of cellulase production and biofuel production from lignocellulose.ResultsIn this work, the role of the mitogen-activated protein kinase (MAPK) signal transduction pathways on cellulase formation was investigated. The deletion of yeast FUS3-like tmk1 in T. reesei leads to improved growth and significantly improved cellulase formation. However, tmk1 deletion has no effect on the transcription of cellulase-coding genes. The involvement of the cell wall integrity maintenance governing yeast Slt2-like Tmk2 in cellulase formation was investigated by overexpressing tmk3 in T. reesei Δtmk2 to restore cell wall integrity. Transcriptional analysis found little changes in cellulase-coding genes between T. reesei parent, Δtmk2, and Δtmk2::OEtmk3 strains. Cell wall integrity decreased in T. reesei Δtmk2 over the parent strain and restored in Δtmk2::OEtmk3. Meanwhile, cellulase formation is increased in T. reesei Δtmk2 and then decreased in T. reesei Δtmk2::OEtmk3. ConclusionsThese investigations elucidate the role of Tmk1 and Tmk2 on cellulase formation: they repress cellulase formation, respectively, by repressing growth and maintaining cell wall integrity, while neither MAPK regulates the transcription of cellulase-coding genes. This work, together with the previous investigations, suggests that all MAPKs are involved in cellulase formation, while Tmk3 is the only MAPK involved in signal transduction for the regulation of cellulase expression on the transcriptional level.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-017-0789-x) contains supplementary material, which is available to authorized users.

The Duality of the MAPK Signaling Pathway in the Control of Metabolic Processes and Cellulase Production in Trichoderma reesei

“…In the T. reesei database ( http://genome.jgi-psf.org/Trire2/Trire2.home.html ), three genes are annotated to encode MAPK pathway members ( tmk1, tmk2, and tmk3) . Recent reports have shown that tmk2, tmk1 , and tmk3 signaling pathways may control different processes in this fungus, including cell wall integrity, cellulase production, biomass accumulation, sporulation, and resistance to high osmolarity 24 , 28 – 30 , however, these studies only examined the expression of a small number of genes. In the current study, we conducted a RNA sequencing-based global gene expression analysis to reveal the functions of TMK1 and TMK2 in T. reesei .…”

New Genomic Approaches to Enhance Biomass Degradation by the Industrial FungusTrichoderma reesei

“…In T. reesei , different signaling pathways have been described to be involved with fungal development and environment sensing. Among these, the signaling pathways dependent on G protein, cAMP, Ras-GTPases, protein kinases, phosphatases, calcium, and MAPK are the mostly characterized intracellular pathways although some aspects remain unclear [ 95 – 104 ]. Several studies showed the involvement of G α proteins in the regulation of cellulase gene transcription by light [ 105 , 106 ].…”

Precision engineering of the transcription factor Cre1 inHypocrea jecorina (Trichoderma reesei)for efficient cellulase production in the presence of glucose

“…Moreover, it was shown that the disruption of cre1 in T. reesei, or its replacement with a cre1 mutant, inhibits biomass accumulation and leads to a decrease in cellulase production (Nakari-Setä lä et al, 2009;Wang et al, 2019). Furthermore, it was reported that CCR is achieved with the phosphotransferase system (Wang et al, 2017;Liu et al, 2020). Post-translational modifications, especially phosphorylation, of the proteins involved, including Cre1, play an essential role in signal transduction to achieve CCR (Jiang et al, 2018;Horta et al, 2019).…”