Protein Profiles of Neurospora Crassa and the Effects of NIT-2 Under Varying Levels of Nitrogen Availability

Abstract

The fungus Neurospora crassa, like most fungi, is very metabolically flexible. N. crassa metabolizes ammonia as a preferred nitrogen source, but has the ability to metabolize other nitrogen sources when the need arises. Furthermore, the nitrogen metabolism of N. crassa is heavily controlled by the gene nit-2. This study analyzes the protein profiles of both wild type N. crassa and a nit-2 mutant N. crassa grown on both Vogels minimal media, which contains ammonia, or Westergaards media, which contains nitrate. Protein was extracted from N. crassa tissue of each genetic composition from each growth medium and analyzed by two-dimensional gel eletrophoresis (2DGE) with the resulting gels being imaged by the PharosFX[Trademark] imaging system and analyzed by the use of PDQuestFX[Trademark] software. The study showed that protein profiles change based on the nitrogen source and whether the nit-2 gene was active. N. crassa grown under poor nitrogen had a significantly lower number of protein spots than when grown under a preferred nitrogen source for both the wild type and nit-2 mutant strains. When grown in poor nitrogen over 100 proteins were produced by the wild type that did not match the Vogels grown counterpart and there were over 60 proteins that were produced by the wild type that were not produced by the nit-2 mutant under the same condition. The identified proteins include a heat-shock protein, a translation Sh3-like protein, an enolase, an aldolase, and a mitochondrial aconitate. Spot differences also suggest a new, previously not discussed role for nit-2 as a possible repressor under normal growth conditions.