The effects of extracellular pH and of the transcriptional regulator PACI on the transcriptome of Trichoderma reesei

Microbial Cell Factories

Research

Markku Saloheimo¹  Dhinakaran Sivasiddarthan¹  Nina Aro¹  Mari Häkkinen¹  Tiina M Pakula¹ 

[1] VTT Technical Research Centre of Finland, P.O. Box 1000, FI-02044 VTT, (Tietotie 2, Espoo), Finland;

关键词: Trichoderma reesei;    Ambient pH;    pac1;    Gene regulation;    Gene expression;    Carbohydrate active enzymes;    Cellulase;    Hemicellulase;    Transcriptional profiling;   

DOI  :  10.1186/s12934-015-0247-z

 received in 2014-06-01, accepted in 2015-04-20,  发布年份 2015

来源: Springer

【 摘 要 】

BackgroundExtracellular pH is one of the several environmental factors affecting protein production by filamentous fungi. Regulatory mechanisms ensure that extracellular enzymes are produced under pH-conditions in which the enzymes are active. In filamentous fungi, the transcriptional regulation in different ambient pH has been studied especially in Aspergilli, whereas the effects of pH in the industrial producer of hydrolytic enzymes, Trichoderma reesei, have mainly been studied at the protein level. In this study, the pH-dependent expression of T. reesei genes was investigated by genome-wide transcriptional profiling and by analysing the effects of deletion of the gene encoding the transcriptional regulator pac1, the orthologue of Aspergillus nidulans pacC gene.ResultsTranscriptional analysis revealed the pH-responsive genes of T. reesei, and functional classification of the genes identified the activities most affected by changing pH. A large number of genes encoding especially transporters, signalling-related proteins, extracellular enzymes and proteins involved in different metabolism-related functions were found to be pH-responsive. Several cellulase- and hemicellulase-encoding genes were found among the pH-responsive genes. Especially, genes encoding hemicellulases with the similar type of activity were shown to include both genes up-regulated at low pH and genes up-regulated at high pH. However, relatively few of the cellulase- and hemicellulase-encoding genes showed direct PACI-mediated regulation, indicating the importance of other regulatory mechanisms affecting expression in different pH conditions. New information was gained on the effects of pH on the genes involved in ambient pH-signalling and on the known and candidate regulatory genes involved in regulation of cellulase and hemicellulase encoding genes. In addition, co-regulated genomic clusters responding to change of ambient pH were identified.ConclusionsAmbient pH was shown to be an important determinant of T. reesei gene expression. The pH-responsive genes, including those affected by the regulator of ambient pH sensing, were identified, and novel information on the activity of genes encoding carbohydrate active enzymes at different pH was gained.

【 授权许可】

Unknown   
© Häkkinen et al.; licensee BioMed Central. 2015. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.