FIGURE 7.

SdomA is not required for in vivo targeting by PulS but is necessary for efficient secretion of PulA. A, total cell extracts of E. coli producing PulD or PulD variants in the absence and presence of PulS were examined by SDS-PAGE and immunoblotting with PulD and PspA antiserum. Relative percent of PspA was measured with respect to its corresponding control without PulS (100%). Mu, PulD multimer; Mo, PulD monomer. B, total cell and culture supernatant fractions of E. coli PAP105(pCHAP8243) producing all the Pul factors except PulD and a soluble variant of PulA, complemented with wild type or SdomA mutant PulD. An equivalent of 0.015 absorbance units of culture were separated by SDS-PAGE and immunoblotted with PulA-specific antiserum. Secretion levels are the proportion (%) of the PulA detected in the supernatant fraction.