Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P51532 (transcriptional activator)
 6,546 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Two cellobiohydrolase-encoding genes, cbhA and cbhB, have been isolated from the filamentous fungus Aspergillus niger. The deduced amino acid sequence shows that CbhB has a modular structure consisting of a fungus-type cellulose-binding domain (CBD) and a catalytic domain separated by a Pro/Ser/Thr-rich linker peptide. CbhA consists only of a catalytic domain and lacks a CBD and linker peptide. Both proteins are homologous to fungal cellobiohydrolases in family 7 of the glycosyl hydrolases. Northern blot analysis showed that the transcription of the cbhA and cbhB genes is induced by D-xylose but not by sophorose and, in addition, requires the xylanolytic transcriptional activator XlnR.
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PMID:Two cellobiohydrolase-encoding genes from Aspergillus niger require D-xylose and the xylanolytic transcriptional activator XlnR for their expression. 1050 57

The cellulase system of the filamentous fungus Hypocrea jecorina (Trichoderma reesei) is encoded by several cellobiohydrolase, endoglucanase and beta-glucosidase genes, which are co-ordinately expressed upon induction by cellulose or the disaccharide sophorose. To identify genes, which are specifically expressed under these inducing conditions and possibly related to the induction process, we applied rapid subtraction hybridization (RaSH) to sophorose induced mRNAs from the wild-type strain H. jecorina QM9414 and a mutant strain H. jecorina QM9978, which is defective in the induction of cellulase gene expression. From a total of 224 clones, 22 gene fragments representing 20 different genes were analyzed. These included one gene encoding a PAS-domain protein with similarity to the Neurospora clock modulator VIVID; one gene similar to Podospora anserina ami1 involved in nuclear migration and the genes encoding translation elongation factor 1alpha, the transcriptional activator Hap5, and myo-inositol-1-phosphate synthase; in addition, several genes were detected, whose function is unknown. Some of them did not even have potential homologues in the Neurospora or Fusarium genome databases. The differential regulation of expression of those 20 genes by sophorose in wild-type and mutant was verified by Northern blotting. Their consistent response to additional inducing conditions (cellulose) confirms their interconnection with cellulase formation.
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PMID:Cloning of genes expressed early during cellulase induction in Hypocrea jecorina by a rapid subtraction hybridization approach. 1528 24

ClbR is a Zn(II)2Cys6 transcriptional activator that controls the expression of cellulase-related genes in response to Avicel and cellobiose in Aspergillus aculeatus. A clbR-overexpressing strain (clbR-OE) that expresses the clbR gene at levels sevenfold higher than the control strain sustainably produced xylanolytic and cellulolytic activities during 10-day cultivation of A. aculeatus, enabling synchronization of xylanolytic and cellulolytic activities at a maximum level. However, clbR overexpression did not simultaneously increase levels of all xylanolytic and cellulolytic enzymes. Peptide mass fingerprint analysis revealed markedly increased production of FIa-xylanase in clbR-OE, whereas expression of FIII-avicelase and FII-carboxymethyl cellulase was unaffected and expression of hydrocellulase was lower in clbR-OE than in the control. Northern blot analysis confirmed that these effects of clbR overexpression on enzyme production were mediated at the transcriptional level. These data suggest that ClbR participates in diverse signaling pathways to control the expression of cellulosic biomass-degrading enzymes in A. aculeatus.
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PMID:Effects of clbR overexpression on enzyme production in Aspergillus aculeatus vary depending on the cellulosic biomass-degrading enzyme species. 2541 Jun 17

Calcium signaling plays pivotal roles in the hyphal growth, conidiation, and osmosis sensitivity of fungi through the Ca(2+) /calmodulin-calcineurin-dependent pathway. This study found that an appropriate extracellular Ca(2+) concentration markedly stimulated the hyphal growth, cellulase production, and total protein secretion of the cellulase hyper-producing strain, Trichoderma reesei Rut-C30. Transcription analysis revealed upregulation of not only encoding genes of cellulases and the transcriptional activator XYR1 but also several genes encoding endoplasmic reticulum-chaperones after Ca(2+) addition. The function of CRZ1, T. reesei calcineurin-responsive zinc finger transcription factor 1, was further characterized by gene disruption. Electrophoretic mobility shift assays (EMSAs) in combination with chromatin immunoprecipitation (ChIP) verified that CRZ1 could bind directly to the upstream regions of xyr1 and cbh1 (cellobiohydrolase I-encoding gene) in response to Ca(2+) . A DNase I footprinting assay identified its putative binding consensus site (5'-[T/G]GGCG-3' or 5'-GGGC[G/T]-3'). EMSAs confirmed that CRZ1 competed for occupancy of the xyr1 promoter with another transcription factor, ACE1. These results revealed putative signaling pathways downstream of calcineurin in response to extracellular Ca(2+) involved in upregulation of cellulose degradation-related genes, reflecting progress in the study of Ca(2+) signaling in filamentous fungi. This study also provides insight that will facilitate further improvement of (hemi-)cellulase production by T. reesei.
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PMID:Characterization of the Ca(2+) -responsive signaling pathway in regulating the expression and secretion of cellulases in Trichoderma reesei Rut-C30. 2710 92

Cellulase production in the model cellulolytic fungus Trichoderma reesei is subject to a variety of environmental and physiological conditions involving an intricate regulatory network with multiple transcription factors. Here, we identified the mating type locus protein MAT1-2-1 as an interacting partner for the key transcriptional activator Xyr1 of T. reesei cellulase genes. Yeast two-hybrid and GST pulldown analyses revealed that MAT1-2-1 directly interacted with the putative transcription activation domain (AD, 767~940 aa) and the middle homology region (MHR2, 314~632 aa) of Xyr1. Disruption of the mat1-2-1 gene compromised the induced expression of cellulase genes with Avicel in response to light or with lactose. Chromatin immunoprecipitation (ChIP) demonstrated that MAT1-2-1 was recruited to the cbh1 (cellobiohydrolase 1-encoding) gene promoter in a Xyr1-dependent manner. These results strongly support an important role of MAT1-2-1 as a physiological cofactor of Xyr1, and suggest that MAT1-2-1 represents another regulatory node that integrates the light response with carbon source signaling to fine tune cellulase gene transcription.
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PMID:The mating type locus protein MAT1-2-1 of Trichoderma reesei interacts with Xyr1 and regulates cellulase gene expression in response to light. 2922 81