Neurospora crassa glucose - repressible gene -1 (Grg-1)‎ promoter controls the expression of neurospora tyrosinase gene in a clock-controlled manner

الملخص EN

In this study sphaeroplasts of white Neurospora crassa mutant auxotroph for aromatic amino acids atom 9 qa-2 inv, was transformed by the pKF-Tyr7-wt DNA construct.

This construct contains the promoter of Neurospora crassa glucose-repressible gene-1 (Grg-1) upstream of Neurospora tyrosinase gene.

The cotransformation of this mutant with pKF-Tyr7-wt construct and the pRAL-1, a plasmid which contains the Neurospora qa-2+ gene,transform it to prototroph.

The transformant contains the tyrosinase gene which catalyzes the unique step in the synthesis of the black pigment melanin.

The activity of the tyrosinase in this transformant was followed by measuring the absorbance of the dark coloured pigment at 332 nm.

The maximum of the tyrosinase activity was shown at 16,36 and 56 hours after the shift of the transformed myce-lia from constant light (LL) to constant dark (DD), The rate of the enzyme activity was changed according to ciradian cycle of 20 hours.

This Grg 1/tyrosinase construct provides a good system to study the temporal control of gene expression and the interaction between the different environmental cues that affects gene expression.