Examination of the σ<sup>E</sup> (RpoE) levels from different genetic backgrounds and cell fractions.

<p>σ<sup>E</sup> was detected by Western blots from protein samples obtained from whole cells (<b>A</b>), soluble (<b>B</b>, periplasm and cytoplasm) and insoluble (<b>C</b>, membranes) fractions. TolC-specific and σ<sup>E</sup>-specific antibodies were used in (<b>A</b>), while antibodies raised against σ<sup>E</sup> and a MalE-TolC fusion protein were used in (<b>B</b>) and (<b>C</b>). The MalE-TolC fusion antibodies were used to verify the purity of soluble (MalE) and insoluble or membrane (TolC) fractions. Relevant genotypes of the strains are shown at the top.</p>