Analysis of the role of the two phosducin-like proteins of Hypocrea jecorina (anamorph Trichoderma reesei)

01.01.2008 - 31.12.2010
Scholarship
The ascomycete Hypocrea jecorina (anamorph Trichoderma reesei) nowadays is the most important industrial producer of cellulases. These enzymes are regulated at the transcriptional level and one activator as well as two repressors of cellulase gene expression have been identified to date. Also carbon catabolite repression mediated by Cre1 was found to play an important role in this process. However, much less is known on how the environmental signal which leads to the adjustment of cellulase gene expression to altered conditions is transduced. Recent findings indicated that the transcription of the cellulase genes is significantly influenced by light and that this response is modulated by the PAS-domain protein ENVOY. Consequently, also the components of the common signaling pathway of heterotrimeric G-proteins, the two Gá proteins GNA1 and GNA3 have been analysed for their effect on cellulase gene expression as well as for the impact of light on their function. Indeed, instead of a direct, receptor-mediated function in induction of cellulase gene expression, a light dependent regulatory function in cellulase gene expression was found. This led to a more detailed analysis of this pathway, since the link between heterotrimeric G-protein signaling and light response could not yet be identified. This link would bring about the light signal and modulate the activity of the pathway accordingly by amplifying or attenuating the signal to be transduced. Primary candidates for such a function are the phosducin like proteins, which are known to modulate the strength of the G-protein signal by changing the availability of the Gâã subunits. Since the Gâã complex has been shown to influence the abundance of Gá subunits, a function of phosducins in cellulase regulation is likely. Studies on mammalian phosducins also revealed a function in the transduction of light signals, which has not yet been studied in fungi. The genome of Hypocrea jecorina comprises 2 open reading frames encoding proteins with significant similarities to characterized phosducins of other fungi. In this project the dependence of cellulase gene expression on phosducins shall be investigated. Therefore I will analyse the transcription of cellulases in phosducin-deletion mutant strains under defined conditions of light and darkness, as well as the connection between the G-protein á subunits GNA1 and GNA3 and phosducins concerning (light-modulated) cellulase gene expression. Based on these data the global targets of the postulated regulatory/signalling function of the phosducin proteins in Hypocrea jecorina shall be investigated.

People

Project leader

Institute

Grant funds

  • Österr. Akademie der Wissenschaften (National) Austrian Academy of Sciences

Research focus

  • Biological and Bioactive Materials: 100%

Keywords

GermanEnglish
Cellulase Genexpressioncellulase gene expression
Lichtreaktionlight response
Hypocrea jecorinaHypocrea jecorina
phosducin like proteinsphosducin like proteins
Signal Transduktionsignal transduction

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