Fig 9.

Inhibition of cell lysis by phosphate occurs in the absence of de novo protein synthesis. The malate dehydrogenase activity in cell-free supernatants is shown. (A) DE442, DE442 ΔcckA, DE442 ΔcckA(pRCckA), and DE555 cells resuspended in RCVm defined medium lacking phosphate (bars labeled 0) or containing 10 mM added phosphate (bars labeled 10); (B) DE442 resuspended in Tris-HCl buffer containing no (bars labeled 0) or 10 mM (bars labeled 10) added phosphate (C) DE442 treated with 0 or 60 μg/ml gentamicin and resuspended in RCVm defined medium lacking phosphate. Cells were resuspended to an OD₆₆₀ of 5.0 (A and B) or 0.5 (C). For panel B, activity is expressed relative to the activity in RCVm lacking phosphate. For panel C, activity was multiplied by 10 for direct comparison with experiments using an OD₆₆₀ of 5.0. Error bars represent the standard deviations of three biological replicates.