FIG. 6.

Effect of the Q93N mutation of PrrB on puf expression. R. sphaeroides PRRB1 strains carrying pPRRB4 or pPRRB4Q93N were grown aerobically or anaerobically (under dark-DMSO conditions) as described for Fig. 1. Expression of the puf operon was analyzed by RT-PCR as described in Materials and Methods. Total RNA was isolated from aerobically (+O₂) or anaerobically (−O₂) grown R. sphaeroides PRRB1 strains carrying the corresponding plasmids, and cDNA was synthesized from 5 μg of total RNA. The PCR products were loaded onto a 2% (wt/vol) agarose gel, yielding 145-bp and 173-bp bands for pufB and the 16S rRNA gene, respectively.