Nitrogen metabolite and nitrate signalling.

Ref ID: 15625

Author: Mark X Caddick1, Igor Morozov1, Greg Fitzgibbon1, Ammar Razak1, Joseph Strauss2 and Meriel Jones1.

Author address:

1 Biological Sciences, The University of Liverpool, UK. 2 Institut für Angewandte Genetik und Zellbiologie, BOKU-University, Vienna, Austria.

Full conference title:

23rd Fungal Genetics Conference

Date: 15 March 2014


The GATA transcription factor AreA, which mediates nitrogen metabolite signalling in the filamentous fungus Aspergillus nidulans, is modulated by at least four distinct mechanisms. Our recent work has investigated two of these; the TOR kinase pathway and regulated transcript stability. In S. cerevisiae the TOR pathway acts via Ure2p to modulate the AreA orthologue Gln3p, and represents the predominant signalling mechanism. A. nidulans does not have a Ure2p orthologue but we have shown that the TOR pathway still contributes to nitrogen metabolite signalling through AreA. Previously we have shown that the areA transcript degrades rapidly in the presence of primary nitrogen sources (glutamine, ammonia) whilst remaining stable under conditions of nitrogen limitation, derepressing transcription of many genes involved in nitrogen metabolism. This 3′ UTR-dependent degradation is preceded by rapid deadenylation. We have now demonstrated that nitrogen metabolites modulate the stability of further transcripts in these pathways, either accelerating or retarding decay. These include the niaD and niiA transcripts which are required for the reduction of nitrate to glutamine. Both transcripts degrade rapidly in the presence of glutamine and conversely, are stabilised by intracellular nitrate. Furthermore, when both glutamine and nitrate are present, these transcripts are stable, ensuring that nitrate and the toxic intermediate nitrite are always removed. Degradation of the niaD transcript is triggered by deadenylation, which is dependent on its 5′ UTR. Nitrate inhibits poly(A) shortening even in the presence of glutamine. Therefore mRNA degradation, mediated through the poly(A) tail, is a fundamental part of the adaptive response to specific environmental signals.

Abstract Number: 372

Conference Year: 2005

Link to conference website: NULL

New link: NULL

Conference abstracts, posters & presentations

Showing 10 posts of 17130 posts found.
  • Title





Our sponsors