Etk K545M mutant failed to support capsule production.

<p>EPEC strains, including wild type, <i>etk::kan</i> mutant and the mutant complemented with plasmids pOI277 (pEtk) or pMS3239 (pEtk K545M), were grown under conditions that allowed capsule production. After harvesting, proteins and capsular polysaccharide were extracted. (A) The amount of Etk and phosphorylated Etk were assessed by Western blot using anti-Etk and anti-phosphotyrosine (anti-PY) antibodies. Each lane is labeled with the strain (above blot) and antibody (on left). (B) Purified capsular polysaccharide extracted from bacteria was serially diluted to generate a dot blot that was developed with anti-O127 antibody. Wild-type EPEC and <i>etk</i> mutant were used as positive and negative controls, respectively. The strains are indicated above each serial dilution.