Identification of new genes involved in metabolic responses to exogenous phosphate sensing in Neurospora Crassa

GRAS DE; SILVEIRA HC; MARTINEZ-ROSSI NM; ROSSI A

Córdoba

Congreso; XI Congreso Argentino de Microbiología; 2007

Asociación Argentina de Microbiología

The capacity to respond successfully to environmental stress is essential for cell survival. The microorganisms are extremely adaptable to variations in nutrients, salinity, temperature, and pH. The mechanisms responsible for these adaptive responses in fungi and yeasts are very complex and involve signal transduction networks that enable them to survive under extreme conditions. Many proteins that function in nutrient acquisition, storage and utilization have been identified but the molecular details of their regulation are not well understood. The phosphorus acquisition system in Neurospora crassa includes four regulatory genes: nuc-2+, preg+, pgov+, and nuc-1+. In an attempt to identify genes involved in metabolic responses to exogenous Pi sensing, we employed suppression subtractive hybridization (SSH) between RNA isolated from the wild type and nuc-2 A mutant strains (FGSC#1996) grown under Pi starvation, pH 5.4. Following SSH, expression of clones was examined using dot-blot macro-arrays. Of the 900 clones arrayed, approximately 21% were differentially regulated. A total of 66 differentially up-regulated and 124 down-regulated clones were identified and sequenced. Virtual and Northern blot analyses of selected genes confirmed the differential gene expression. Genes encoding proteins involved in the initiation of mRNA translation were identified among the up-regulated sequences, including the translation initiation factor eIF3, 40S ribosomal proteins S13, S16, and the ubiquitin-ribosomal protein S27a fusion protein. The up-regulation of these genes may result in the recruitment of the cellular translation machinery responsible for translation initiation of a subpopulation of mRNAs. Among the genes found to be down-regulated in nuc-2 A, six were involved in gluconeogenesis and oxidative phosphorylation.