FIG 3.

(A) Confocal scanning laser microscope image of protein binding assay showing the dispersal of green and red microspheres following preincubation with a nonbinding protein (i.e., bovine serum albumin [negative control]). Note that the majority of beads with different fluorescence are observed separately (i.e., as red or green only), with a few overlapping signals (i.e., yellow) due to random positional overlay. (B) Coalescence of green microspheres incubated with construct 1 (i.e., anammox biofilm S-layer protein amino acids 1254 to 1338) and red microspheres incubated with construct 2 (i.e., amino acids 1354 to 1439). (Inset) Three-dimensional side view of coalesced beads, demonstrating that binding derives from protein interactions and not the overlapping of beads. The samples were prepared in 50 mM MES–5 mM CaCl₂, pH 6.0.