Figure 4.

Evl is essential for actin-based motility of Listeria in mouse brain extracts. (a) Western blot analysis of Evl depletion from Mena (−/−) mouse brain extracts. Lane 1, 15 pmol of recombinant Evl; lane 2, 10 μl mock-depleted extract; lane 3, 10 μl Evl-depleted extract; lane 4, Dynabead-bound Evl after the first cycle of depletion; and lane 5, control Dynabeads used for the mock depletion. The blot was revealed using an anti-Evl mAb. (b) Effect of Evl depletion on Listeria movement in wild-type brain extracts. The percentages of motile bacteria, defined as: (number of motile bacteria/number of total bacteria) × 100 (dark gray bars), and of immotile bacteria that were surrounded by actin clouds, defined as: (number of nonmotile bacteria surrounded by actin clouds/number of total bacteria) × 100 (light gray bars), were determined under each condition. 271 ± 24 bacteria were counted for each measurement. Motile bacteria moved at rates that fell in the range of 0.16 ± 0.06 μm/min in all samples. (c) Effect of Evl depletion on Listeria movement in Mena (−/−) mouse brain extracts. Data are represented as in b. 282 ± 49 bacteria were counted for each measurement.