The gal operon of E. coli is transcribed from two promoters and is regulated by a single gene. The two promoters, PG1 and PG2, are overlapping and are modulated by cyclic AMP and its receptor protein (CRP).
What is the function of the product of the galR gene in regulation of the gal operon?
A. A positive regulator of the gal operon
B. A negative regulator of the gal operon
C. Both a positive and a negative regulator of the gal operon
D. Sigma factor required expression the gal operon