Mapping of two ugp genes coding for the pho regulon-dependent sn-glycerol-3-phosphate transport system of Escherichia coli

Two genes, ugpA and ugpB, coding for a binding protein-dependent sn-glycerol-3-phosphate transport system, were mapped at 75.3 min on the E. coli chromosome. A Tn10 insertion in ugpA resulted in loss of transport activity but still allowed the synthesis of the sn-glycerol-3-phosphate-binding protein. This Tn10 insertion was found to be linked by P1 transduction to pit, aroB, malA, asd, and livH with 2.5, 2.8, 25, 63.5, and 82% cotransduction frequency. An insertion of Mud (Amp(r) lac) in ugpB resulted in the loss of the binding protein. ugpB is closely linked to ugpA. It is either the structural gene for the binding protein or located proximal to it. The analysis of the crosses allowed the ordering of the markers in the clockwise direction as follows: aroB, malA, asd, ugpA, ugpB, livH, pit.