FIG. 3.

Arginine-specific activity partitioning in the bacterial culture. Early stationary-phase cultures of each mutant were separated into cellular, vesicular, and medium fractions, and 20-μl samples of each fraction were assayed against an Arg-specific synthetic substrate as per Materials and Methods. The total Rgp activity in the RgpB⁺ control mutant was set at 100 activity units. Data were obtained from duplicate enzymatic measurements from four independently grown cultures and were normally distributed. Differences in the total arginine-specific activity of each strain against the RgpB⁺ mutant were statistically analyzed using one-way ANOVA with Bonferroni's correction. Values that were significantly different from the value for the RgpB⁺ mutant are indicated by asterisks (*, P < 0.05; ***, P < 0.001).