XprG (PhoG) is a putative transcriptional activator in Aspergillus nidulans. xprG mutants have previously been shown to affect protease production under starvation conditions. XprG is also involved in the production of melanin and phosphate repressible acid phosphatase. In this study, we have used cDNA microarrays to identify other biological pathways in which XprG may be involved. We obtained expression profiles of xprG+ and xprG916; strains, under two growth conditions; one containing a preferred carbon source (glucose) and the other containing no carbon source. A Two-way ANOVA comparison statistical test is being used to analyse any strain and condition effect on the expression profile, and also interactions between them. Results have identified new roles for XprG in mycotoxin synthesis and glucose transport, which have been validated biologically. XprG may also be involved in amino acid metabolism, conidiophore formation and regulation of the cell cycle. HxkC is an atypical mitochondrial hexokinase which affects protease production. Mitochondrial hexokinases have been shown to regulate programmed cell death (PCD). There is genetic evidence that HxkC and XprG are involved in the same regulatory pathway, and that XprG is modulated by HxkC. Apoptotic markers, such as DNA laddering, have been found in hxkC916; strains. This spontaneous cell death is suppressed in hxkC916; double mutants containing a loss of function xprG2 mutation. We propose that XprG is a transcriptional activator, and is a major regulator of the cellular response to starvation.
Full conference title:
9th EUROPEAN CONFERENCE ON FUNGAL GENETICS
- ECFG 9th (2008)