A Common Regulator for the Operons Encoding the Enzymes Involved in d -Galactarate, d -Glucarate, and d -Glycerate Utilization in Escherichia coli

Abstract

ABSTRACT Genes for d -galactarate ( gar ) and d -glucarate ( gud ) metabolism in Escherichia coli are organized in three transcriptional units: garD , garPLRK , and gudPD . Two observations suggested a common regulator for the three operons. (i) Their expression was triggered by d -galactarate, d -glucarate, and d -glycerate. (ii) Metabolism of the three compounds was impaired by a single Tn 5 insertion mapped in the yaeG gene (proposed name, sdaR ), outside the d -galactarate and d -glucarate systems. Expression of the sdaR gene is autogenously regulated.