FIG. 3.

Complementation of an E. coli argE mutation by the M. xanthus argE gene. E. coli cells carrying a point mutation in argE were transformed with either pBluescript KS(+) (pBS KS+) or pBAR114 and assayed for growth on M9 minimal agar plates (14) with or without supplemental arginine (Arg). (Each quadrant of a single plate contains a separate isolate, and corresponding quadrants of the two plates contain the same isolate.) Both strains show growth on plates with supplemental arginine, but only the strain with pBAR114 grows in the absence of arginine.