Reformulating the Hydrolytic Enzyme Cocktail of <i>Trichoderma reesei</i> by Combining XYR1 Overexpression and Elimination of Four Major Cellulases to Improve Saccharification of Corn Fiber

Zhang, Weixin; Guo, Junqi; Wu, Xiaoxiao; Ren, Yuxin; Li, Chunyan; Meng, Xiangfeng; Liu, Weifeng

doi:10.1021/acs.jafc.1c05946

Cited by 12 publications

(11 citation statements)

References 49 publications

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“…In a recent study, the overexpression of Xyr1 in a T. reesei strain lacking four major cellulase genes resulted in a completely different secretome profile in the presence of glucose or lactose, as compared to the wild type T. reesei strain. Increased expression of endoglucanases, betaglucosidases, arabinofuranosidases and other non-hydrolytic proteins as well was observed, all of which contributed to a greater hydrolytic potential of the crude enzyme even with untreated corn fiber [ 49 ].…”

Section: Transcriptional Regulators Involved In the Regulation Of Cel...mentioning

confidence: 99%

Factors regulating cellulolytic gene expression in filamentous fungi: an overview

2022

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The growing demand for biofuels such as bioethanol has led to the need for identifying alternative feedstock instead of conventional substrates like molasses, etc. Lignocellulosic biomass is a relatively inexpensive feedstock that is available in abundance, however, its conversion to bioethanol involves a multistep process with different unit operations such as size reduction, pretreatment, saccharification, fermentation, distillation, etc. The saccharification or enzymatic hydrolysis of cellulose to glucose involves a complex family of enzymes called cellulases that are usually fungal in origin. Cellulose hydrolysis requires the synergistic action of several classes of enzymes, and achieving the optimum secretion of these simultaneously remains a challenge. The expression of fungal cellulases is controlled by an intricate network of transcription factors and sugar transporters. Several genetic engineering efforts have been undertaken to modulate the expression of cellulolytic genes, as well as their regulators. This review, therefore, focuses on the molecular mechanism of action of these transcription factors and their effect on the expression of cellulases and hemicellulases.

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Section: Transcriptional Regulators Involved In the Regulation Of Cel...mentioning

confidence: 99%

Factors regulating cellulolytic gene expression in filamentous fungi: an overview

2022

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“…A major issue associated with the cost-effective production of bioethanol is optimization of the fungal platform to increase enzyme production [9,10]. Many transcription factors play an important role in the process of cellulase production [11], including the main repressor, CRE1, related to carbon catabolite repression (CCR) [12][13][14], and the crucial transcription activators XYR1 [15][16][17] and ACE3 [18][19][20]. Interestingly, T. reesei only produces enzymes abundantly in the presence of inducible carbon sources, such as Avicel and lactose [21].…”

Section: Introductionmentioning

confidence: 99%

The Ras small GTPase RSR1 regulates cellulase production in Trichoderma reesei

Qiu

Cai

et al. 2023

Preprint

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Background: Lignocellulose is known to be the most abundant renewable resource in the world and has attracted widespread attention because of its ability to produce sugars from the hydrolysis of cellulases and hemicellulases secreted by filamentous fungi. Several studies have revealed that the Ras small GTPase superfamily regulate important cellular physiological processes, including synthesis of metabolites, sporulation, cell growth, cell differentiation, and apoptosis. However, how and to what extent Ras small GTPases are participated in cellulase production remain unknown. Results: In this study, we found that the putative Ras small GTPase RSR1 repressed the expression of cellulases and xylanases. Knockout of rsr1 (∆rsr1) significantly increased cellulase production and decreased the expression levels of ACY1-cAMP-protein kinase A (PKA) signaling pathway genes and intracellular cyclic adenosine monophosphate (cAMP) levels. Loss of acy1 based on ∆rsr1 (∆rsr1∆acy1) could further increase the cellulase production and expression levels of cellulase genes, while overexpression of acy1 based on ∆rsr1 (∆rsr1-OEacy1) significantly reduced the cellulase production and transcriptional levels of cellulase genes. Our results revealed that RSR1 repressed cellulase production via ACY1-cAMP-PKA pathway. Transcriptome analysis revealed significantly increased expression of three G-protein coupled receptors (GPCRs;tre62462, tre58767, tre53238) on rsr1 knockout and approximately two-fold higher expression of ACE3 and XYR1, which transcriptionally activated cellulases. ∆rsr1∆ tre62462 exhibited a decrease in enzyme activity compared to ∆rsr1, while ∆rsr1∆tre58767 and ∆rsr1∆tre53238 showed a remarkable improvement compared to ∆rsr1. We revealed that GPCRs on the membrane sense extracellular signals and transmit them to rsr1 and then to ACY1-cAMP-PKA, thereby repressing the expression of the cellulase activators ACE3 and XYR1. These data indicated the crucial role of Ras small GTPase in regulating cellulase gene expression. Conclusions: Here, we demonstrate that some G-protein-coupled receptors and Ras small GTPases play a key role in signal transduction and cellulase gene regulation in T. reesei. Understanding the roles of these components in the regulation of cellulase gene transcription and understanding the signaling processes in T. reesei can lay the groundwork for understanding and transforming other filamentous fungi.

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“…Sacchari cation is a vital step in the degradation of lignocellulose and is catalyzed by cellulases produced from lamentous fungi, such as Trichoderma reesei and Aspergillus nidulans [3][4][5]. T. reesei is industrially used as a model strain for cellulase production because of its excellent extracellular enzyme production, safety and reliability [6,7]. Xyr1, a global transcriptional activator, regulates the expression of cellulase and xylanase genes [8].…”

Section: Introductionmentioning

confidence: 99%

Mechanism of Zn2+ regulating cellulase production in Trichoderma reesei Rut-C30

Chen

et al. 2023

Preprint

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Background Trichoderma reesei Rut-C30 is a hypercellulolytic mutant strain that degrades abundant sources of lignocellulosic plant biomass into renewable biofuels. Zn2+ is an activator of enzymes in almost all organisms; however, its effect on cellulase activity has not been reported in T. reesei. Results Although high concentrations of Zn2+ severely hampered the extension of T. reesei mycelia, adding 1–4 mM Zn2+ improved cellulase production in T. reesei high-yielding cellulase-producing strain Rut-C30. The expression levels of the major cellulase genes and two critical transcription activators (xyr1 and ace3) increased significantly on Zn2+ addition. Transcriptome analysis revealed that the mRNA level of plc-e encoding phospholipase C, which is involved in the calcium signaling pathway, was enhanced by Zn2+ addition. The disruption of plc-e abolished the cellulase-positive influence of Zn2+ in the early phase, indicating that plc-e is involved in Zn2+-induced cellulase production; furthermore, supplementation with LaCl3 (a plasma membrane Ca2+ channel blocker) and deletion of crz1 (calcineurin-responsive zinc finger transcription factor 1) demonstrated that calcium signaling is partly involved in this process. Moreover, we identified the zinc-responsive transcription factor zafA; the transcriptional level of zafA decreased significantly with Zn2+ stress, and its deletion indicated that zafA mainly mediates Zn2+-induced cellulase production. Conclusions For the first time, we have demonstrated that Zn2+ was toxic to T. reesei and it remarkably promoted cellulase production. This positive influence of Zn2+ was facilitated by the gene plc-e and the transcription factor zafA. These findings provide insights into the role of Zn2+ in T. reesei and a mechanistic study of signal transduction in cellulase synthesis.

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Reformulating the Hydrolytic Enzyme Cocktail of Trichoderma reesei by Combining XYR1 Overexpression and Elimination of Four Major Cellulases to Improve Saccharification of Corn Fiber

Cited by 12 publications

References 49 publications

Factors regulating cellulolytic gene expression in filamentous fungi: an overview

Factors regulating cellulolytic gene expression in filamentous fungi: an overview

The Ras small GTPase RSR1 regulates cellulase production in Trichoderma reesei

Mechanism of Zn2+ regulating cellulase production in Trichoderma reesei Rut-C30

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