ACT domains that comprise the Glycine Cleavage System Transcriptional Repressor (GcvR) protein, and other related domains
This CD includes the first of the two ACT domains that comprise the Glycine Cleavage System Transcriptional Repressor (GcvR) protein, and other related domains. The glycine cleavage enzyme system in Escherichia coli provides one-carbon units for cellular methylation reactions. This enzyme system, encoded by the gcvTHP operon and lpd gene, catalyzes the cleavage of glycine into CO2 + NH3 and transfers a one-carbon unit to tetrahydrofolate, producing 5,10-methylenetetrahydrofolate. The gcvTHP operon is activated by the GcvA protein in response to glycine and repressed by a GcvA/GcvR interaction in the absence of glycine. It has been proposed that the co-activator glycine acts through a mechanism of de-repression by binding to GcvR and preventing GcvR from interacting with GcvA to block GcvA's activator function. Evidence also suggests that GcvR interacts directly with GcvA rather than binding to DNA to cause repression. Members of this CD belong to the superfamily of ACT regulatory domains.