The role of Aspergillus nidulans’s pumilio family (PUF) RNA binding proteins implicated in mRNA stability during nitrogen metabolism

Sunthorn Chooluck, Igor Morozov, Mariel Jones, Mark Caddick

Author address: 

University of Liverpool, Liverpool, United Kingdom

Abstract: 

The stability of any given transcript plays an important role in determining the level of the mRNA and subsequent gene expression. Highly stable transcripts are optimal for achieving high levels of gene expression. As a consequence RNA stability varies significantly among genes, and in some cases this is directly regulated as a means of controlling gene expression. We have previously demonstrated a differential rate of decay for the areA transcript, which encodes the major transcription factor mediating nitrogen metabolite repression. The areA mRNA is destabilised by the presence of intracellular Gln, a signal of nitrogen sufficiency. The same mechanism is important to the expression of various structural genes involved in nitrogen metabolism, including niiA and niaD. Intriguingly, some of these genes are also subject to an additional regulatory mechanism at the level of RNA stability that stabilises the transcripts in the presence of the respective protein’s substrates. Bioinformatics analysis of the untranslated regions of Aspergillus genes revealed the presence of a number of conserved motifs, including many likely to be involved in interactions with the Pumilio homology domain (Puf) RNA-binding proteins. In other eukaryotes, including Saccharomyces cerevisiae and Drosophila melanogaster, these proteins have been found to coordinate expression of specific groups of genes. In our laboratory, we have identified a number of proteins whose orthologues are shown to be involved in RNA degradation. Amongst these are the five Puf proteins, pufA, pufB, pufC, pufD and pufE. All five A.nidulans’s puf genes have successfully been deleted. Deletion of pufD results in a dramatically reduced response to Gln with respect to destabilisation of areA and meaA transcripts, and the areA transcript also reveals significantly reduced basal degradation. Deletion of pufA appears to disrupt the sexual cycle. The pufB, pufC and pufE deleted strains are currently being characterised
2008

abstract No: 

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Full conference title: 

9th EUROPEAN CONFERENCE ON FUNGAL GENETICS
    • ECFG 9th (2008)