Figure 2. Eater-Fc binding to live Gram-negative bacteria is dependent on prior exposure of bacteria to a cationic antibacterial peptide. (A, left) The ectodomain of the native Eater receptor consists mainly of tandem EGF-like repeats. N- and C-terminal tandem repeats (dark gray) show higher variability than internal repeats (light gray). Eater-Fc (right): the N-terminal 199 amino acids of Eater were fused to an IgG1-Fc tag to generate a soluble fusion protein. (B and C) Pre-formed complexes of biotinylated Eater-Fc with 15 nm gold–streptavidin conjugate were used to reveal binding of Eater to live E. coli in the absence (B) or presence (C) of cecropin A. Electron micrographs, magnification 60,000x.