Regulation of cellulase enzyme expression in Trichoderma

The project aims to provide new information on the transcriptional regulation of expression of cellulase in the filamentous fungus Trichoderma reesei. T. reesei is a fungus exploited extensively commercially for production of native (mainly cellulases) enzymes and, increasingly, heterologous proteins. The genome sequence of T. reesei is available (http://genome.jgi-psf.org/Trire2/Trire2.home.html). Although the T. reesei genome encodes for the expression of several cellulases, the cbh1 gene has been the most extensively studied in relation to its expression and the cbh1 promoter is used to drive expression of heterologous proteins. This project will build upon our unpublished data which show, for the first time, the importance of chromatin in its regulation, including changes in nucleosomal positioning during induction and repression. Moreover, we have preliminary data showing protein binding to the ORF during induction, indicating that the ORF is involved in regulation in addition to the promoter region. That is unprecedented in filamentous fungi. The overall Aim of the project is to define new regulatory principles in the transcriptional control of a target gene in a filamentous fungus. The specific experimental Aims of the project are to confirm the nucleosomal rearrangements of the chb1 promoter and ORF during induction and repression and to specify the roles, if any, of known regulators (e.g. Cre1, Ace1) in the nucleosomal rearrangements. A secondary Aim is to define a model for the regulation of cbh1. The project will also explore the role of protein binding to the ORF during transcriptional regulation. The methodologies available for exploration of nucleosomal positioning (involving the isolation of chromatin, nuclease sensitivity assays, and hybridisation studies), culture conditions for induction and repression (and neutral conditions), and some mutant strains for exploration of the roles of some transcription factors are all in place in Nottingham or the research facility of Roal. This project provides an exciting possibility for defining new mechanisms of transcriptional regulation in fungi. The student will receive training in microbiology, genomics and molecular biology and will have the opportunity to interface with mathematicians in Nottingham in order to define a model for the regulation of the cbh1 gene That model can be tested and its relevance to gene regulation in the fungus as a whole examined using gene array methodology, which is only recently available for T. reesei. This new information will be important for Roal, a company that exploits filamentous fungi, including T. reesei, in its business.