FIG. 4.

Schematic organization of the ORFs identified in plasmids pSM1 to pSM13. The arrows indicate the locations and the directions of transcription of the ORFs in the different plasmids. Those ORFs involved in nickel resistance are indicated by gray arrows. Arrows shaded with vertical bars indicate the presence of predicted transmembrane helices. Asterisks indicate incomplete ORFs. Plasmids pSM1, pSM3, and pSM12 were mutagenized by in vitro transposition, and vertical arrowheads indicate transposon insertions that either abolish the resistance phenotype (filled in black) or do not affect the resistance phenotype (not filled).