FIG. 4.

Effects of temperature, growth phase, and ion concentration on yadA expression. (A) Overnight and exponential-phase cultures of YP28 (yadA-phoA) grown at 25 or 37°C in LB medium were incubated without (wo) or with 20 mM MgCl₂ or 20 mM Na oxalate or with both 20 mM MgCl₂ and 20 mM Na oxalate for 3 h. Subsequently, the alkaline phosphatase activity of the cultures was determined. (B) Cell extracts from equal amounts of Y. pseudotuberculosis YPIII bacteria grown in LB medium under the conditions indicated were prepared, and the OD of the cultures was adjusted. Equal amounts of the cell extracts were separated on an SDS-10% polyacrylamide gel and transferred onto an Immobilon membrane. The YadA protein was detected by a polyclonal antibody directed against a C-terminal fragment of the YadA protein. Lanes: 1 to 8, YPIII grown at 25°C; 9 to 16, YPIII grown at 37°C. A minus sign indicates without, and a plus sign indicates with, the addition of 20 mM MgCl₂ or 20 mM Na oxalate to the growth medium. A prestained protein molecular size marker was loaded on the left (M). The position of the YadA protein is indicated on the right.