Effects of the qa-1F Activator Protein on the Expression of Quinic Acid Induced Genes in Neurospora crassa

Abstract

Neurospora crassa, like most fungi, is very flexible metabolically. When a preferred carbon source, such as dextrose, is unavailable, N. crassa has the ability to metabolize quinic acid. To do this, the quinic acid gene cluster is up-regulated by the qa-1F activator. This study uses a mutant form of N. crassa in which the qa-1F gene is knocked out. The protein profiles of N. crassa wild-type and qa-1F knockout when grown on both dextrose and quinic acid were analyzed and compared. The wild-type and knockout strains were first grown on 2% dextrose and then shifted either to fresh dextrose or 0.3% quinic acid. The proteins from these tissues were then extracted, quantitated, and separated using two-dimensional gel electrophoresis (2DGE). The 2DGE gels were then analyzed using PDQUESTTM. Cross-conditional comparisons were made and protein spots unique to each condition were identified. These gel comparisons show that, when grown on a preferred carbon source, nearly twice as many proteins are up-regulated than when grown on quinic acid. Also, the qa-1F knockout protein profiles had far fewer protein spots than their wild-type counterparts for both carbon sources. Protein spots were then selected, excised, and sent to the Ohio State University for mass spectrometry and bioinformatic analysis. Two proteins affected by the presence of qa-1F when grown on quinic acid were identified as hypothetical proteins NCU 04072 and NCU 08332 likely be a catechol dioxygenase and a translational protein SH3-like protein, respectively.