Novel Promoter Sequence Required for Inductive Expression of theAspergillus nidulansEndoglucanase GeneeglA

Abstract

Expression of the eglA gene, encoding for a major endoglucanse EG A in Aspergillus nidulans, is induced by cellulose and cellobiose, but not by xylose. This suggests that induction is independent of XlnR, a transcriptional activator of xylanolytic and cellulolytic genes in Aspergillus. Mutational analysis of the eglA promoter was performed to identify the novel cis-element responsible for XlnR-independent induction. The region spanning -153 to -138 (CCGTACCTTTTTAGGA), designated CeRE(Cellulose Responsive Element), was found to be the upstream activating element essential to inductive expression of the eglA gene.

XlnR-independent signaling pathway regulates both cellulase and xylanase genes in response to cellobiose in Aspergillus aculeatus

“…5c, d). All of these regions contained the conserved sequences within CeRE, which was identified as the upstream activating element essential to induce the expression of eglA in A. nidulans (Endo et al 2008). Therefore, a mutagenesis scheme was undertaken in which regions containing conserved sequences were sequentially altered (Fig.…”

“…It also activates the transcriptional regulation of inducer-providing enzymes, such as b-xylosidase (BXLI) and b-glucosidase (BGLI), governs signals from various inducers (xylose, xylobiose, and sophorose), and triggers the transcription of those genes. However, it has been revealed in recent years that the expression of several genes encoding cellulolytic enzymes is controlled by an XlnRindependent signaling pathway in A. nidulans and F. graminearum (Endo et al 2008;Brunner et al 2007).…”

“…Furthermore, cellobiose with DNJ induced the transcription of cmc2 and xynIa, whereas cmc1 and xynIb were not induced. GUS reporter fusion analyses of truncated and mutated cbhI promoters revealed that three regions were necessary for effective cellulose-induced transcription, all of which contained the conserved sequence 5 0 -CCGN 2 CCN 7 G(C/A)-3 0 within the CeRE, which has been identified as the upstream activating element essential for expression of eglA in A. nidulans (Endo et al 2008). The data therefore delineate a pathway in which A. aculeatus perceives the presence of cellobiose, thereby activating a signaling pathway that drives cellulase and hemicellulase gene expression under the control of the XlnR-independent regulation through CeRE.…”

Effects of clbR overexpression on enzyme production in Aspergillus aculeatus vary depending on the cellulosic biomass-degrading enzyme species

“…An equal volume of culture supernatant from each strain was analyzed by two-dimensional (2D) polyacrylamide gel electrophoresis using a non-linear immobilized pH gradient (3)(4)(5)(6)(7)(8)(9)(10) in the first dimension of separation. Detected protein spots were excised from the gels, digested with trypsin, and analyzed by LCMS-IT-TOF.…”

“…4) These data demonstrated that enzyme production could be improved by exploiting the function of a pathway-specific positive transcription factor. Although Xyr1, a XlnR homolog in T. reesei, plays a major role in all induction modes of genes encoding cellulosic biomass-degrading enzymes, it has been reported that a XlnR-independent signaling pathway exists in other species such as Aspergillus nidulans, 5) A. oryzae,…”