Transmission electron micrographs of ActM and rabbit actin with PfnM.

<p>Top row shows ActM filaments without PfnM (left, “-”) and with 4-fold molar excess of PfnM. Bottom row shows rabbit actin controls. Scale bars: 200 nm.</p

Fluorescence microscopy of PfnM binding to ActM polymers.

<p>FITC stained PfnM (green) co-localizes with phalloidin-TRITC stained ActM polymers (red). Single ActM bundles are covered with PfnM along their length. Fluorescence signals increase with increasing PfnM concentration, molar ratios of ActM:PfnM are indicated. Images on the left hand side show an overview (scale bars: 5 µm), magnifications of corresponding single aggregates are on the right (scale bars: 2 µm).</p

PfnM-GFP expression in <i>E.coli.</i>

<p>In <i>E.coli</i>, PfnM-GFP distributes evenly in the cytoplasm (A1-3) or is localized to the cell poles (B1-D). Scale bars: 2 µm.</p

ActM-GFP expression in <i>E.coli.</i>

<p>ActM-GFP adopts a variety of shapes and apparently is not freely diffusible in <i>E.coli</i>. All images show the GFP-channel, except for A2 and A3 which display the transmission channel and an overlay of transmission and GFP, respectively. Image F shows anti-actin/TRITC immunofluorescence of untagged ActM expressed in <i>E.coli</i>. Scale bars: 2 µm.</p

A hollow enclosure in cells co-expressing PfnM-GFP and ActM.

<p>Co-expression of PfnM-GFP and ActM gives rise to a hollow compartment. This enclosure is not dynamically rearranged, as fluorescence does not recover 30 minutes after bleaching (D4, E4, the bleached region is indicate by a red rectangle). Z-sectioning and 3D reconstructions of the cell shown in F. Stepwise rotations along the x-axis of the total enclosure (G1-4) or its “top” half (H1-5) is shown. Immunodetection of ActM in the enclosures of <i>E.coli</i> expressing both ActM and PfnM-GFP reveals a co-localization (J1-3). Images show either GFP-channel (“GFP”), transmission image (“trans”) or an overlay of both (“merge”). Scale bars in Z-sectioning and 3D reconstruction: 1 µm. All other scale bars: 2 µm.</p

Phalloidin staining of polymerized rabbit actin and ActM.

<p>Rabbit actin (left) polymerizes into long filaments forming an interwoven network. ActM polymers (right) appear as short filaments assembling in bundles and sheets. Scale bars: 5 µm.</p