Regulation of gene expression by phosphate in Neurospora crassa

GRAS DE; REIS EM; TAHIRA AC; PERES NT; PRADE RA; MARTINEZ-ROSSI NM; ROSSI A

Asilomar

Conferencia; 25th Fungal Genetics Conference at Asilomar; 2009

Genetics Society of America

Pi acquisition system in Neurospora crassa includes at least four regulatory genes: nuc-2, preg, pgov and nuc-1. Under limiting Pi conditions, NUC-2 inhibits the functioning of the PREG-PGOV complex, allowing the activation of the transcription factor NUC-1 and the expression of genes involved in phosphate acquisition. Aiming at a better comprehension of the nuc-2 functionality in gene expression regulation in response to exogenous Pi levels, two cDNA subtraction libraries were constructed comparing N. crassa wild type St.L.74A and nuc-2A strains, grown under Pi starvation. We obtained 52 NUC-2 up- and 16 down-regulated genes. Among the NUC-2 negatively modulated genes, we identified the MAK-2 (mitogen-activated protein kinase-2) protein coding gene, involved in intracellular signaling. The functional role of this gene in the extracellular Pi sensing was evaluated by microarrays, comparing wild type and mak-2 strains responses under Pi starvation. We identified 4214 MAK-2 regulated genes, among them the cyclin coding gene, preg. Furthermore, 3174 genes regulated in response to Pi levels were identified. The results obtained reveal novel molecular aspects of the adaptation to Pi availability, suggesting that mak-2 gene constitutes a novel component of the N. crassa phosphate sensing and signaling pathway.