WcbK is important for LPS-biosynthesis, attenuates survival in blood, and promotes acid resistance.

<p>(<b>A</b>) SDS-PAGE pattern of purified LPS after silver staining. Samples were isolated from <i>C. fetus.</i> subsp. <i>fetus</i> (<i>Cff</i>) 82-40 (lane 1), <i>Cff</i> ATCC 27374 (type B) (lane 2), <i>wcbK</i> mutant K19 (<i>wcbK</i>::Km) (lane 3) and K19 [pSW2] (<i>wcbK in trans</i>) (lane 4); <i>C. fetus</i> subsp. <i>venerealis</i> (<i>Cfv</i>) ATCC 19438 (lane 5) and <i>Cfv</i> 84-112 (lane 6). (<b>B</b>) <i>Cff</i> serum resistance assays. Strains were incubated either with EMEM (-), heat-inactivated (I) or active (A) human serum and colony forming units (CFU) were counted. Results shown are for <i>Cff</i> ATCC 27374, K19 and K19 [pWS2]. <i>Cff</i> 82-40 served as a type A comparator. (<b>C</b>) Same as in (B) but for better visualization, CFU/ml obtained after treatment with active serum are displayed separately. **p<0.002 (<b>D</b>) Acid resistance assays. <i>Cff</i> were incubated in PBS pH range 7.3 to 3.4, plated and CFU determined. Survival after exposure to different pH of the wild type, K19 and K19 [pSW2] was compared. (<b>E</b>) For better visualization, CFU/ml for the three strains after treatment with pH 3.4 were plotted separately. **p<0.003.