FIG. 2.
Dam overproduction results in YopE synthesis and secretion under conditions nonpermissive for the wild type. Whole-cell (WC), membrane (Memb), and supernatant (Sup) fractions were prepared from wild-type (WT) and Dam-overproducing (OP) Y. pseudotuberculosis grown under the indicated conditions. For each growth condition, total protein corresponding to 2.0 × 106 cells was subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis, transferred to polyvinylidene difluoride membrane, and probed with convalescent-phase antisera derived from BALB/c mice infected with wild-type Y. pseudotuberculosis as a source of anti-YopE antibody. Western analysis with YopE antibody confirmed that the 23-kDa low-calcium-responsive protein was YopE. Numbers refer to protein sizes (in kilodaltons).