A Novel Transcriptional Regulator, ClbR, Controls the Expressions of Cellulose8208; and Hemicellulose8208;degrading Enzyme Genes by Two Distinct Mechanisms in Aspergillus aculeatus

Ref ID: 18504

Author:

Emi Kunitake,Shuji Tani,Jun-ichi Sumitani,Takashi Kawaguchi

Author address:

Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Japan  Â 

Full conference title:

11 th European Conference on Fungal Genetics

Abstract:

The cellobiose8208;  and cellulose8208;induction of the FIII8208;avicelase (cbhI) and FII8208;carboxymethyl cellulase (cmc2) genes
were regulated by XlnR8208;independent pathway in Aspergillus aculeatus, which suggests that this fungus possesses
an unknown cellulase8208;genes8208;activating pathway. To identify the novel trans8208;acting regulatory factors controlling
their expressions, we established a positive screening system to monitor the inducibility of the cbhI promoter using
the orotidine 5’8208;phosphate decarboxylase gene (pyrG) as a reporter. Gene disruption library was constructed by T8208;
DNA insertion using Agrobacterium tumefaciens8208;mediated transformation, and transformants were selected for 58208;
fluoroorotic acid (58208;FOA) resistant under the cellulase8208;inducing condition. Of the ~6,000 transformants that we
screened, one 58208;FOA resistant, S48208;22, grew poorly on cellulose media and reduced the cellobiose8208;induced
expression of cbhI. Southern blot analysis and nucleotide sequence of the flanking regions of the T8208;DNA inserted in
S48208;22 indicated that the T8208;DNA located within the coding region of a putative Zn(II)2Cys68208;transcription factor
designated as the cellobiose response regulator (ClbR). Interestingly, the clbR disruption resulted in reduced
expression of not only cbhI and cmc2 but also genes regulated by XlnR in the presence of cellulose. However, the
clbR disruption did not affect for XlnR8208;dependent induction in response to D8208;xylose and L8208;arabinose. The clbR
overexpression led to sustainable cellulase and xylanase production for 10 days, which increased their production
by 28208;  and 58208;fold, respectively. These data demonstrate that ClbR participates in cellulose signaling pathway
regulated by both the XlnR8208;dependent and the XlnR8208;independent pathways.  Â 

Abstract Number: PR7.22

Conference Year: 2012

Link to conference website: http://www.ecfg.info/images/Abstract_Book_Electronic.pdf

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