Synthetic
adhesins and targeting of E. coli cells
to antigens immobilized on a plastic surface. (a) Scheme of the primary
structure of SAs (left) showing the N-terminal domain of intimin (Neae)
as anchoring module, comprising the signal peptide (SP), LysM, β-barrel,
and D0 Ig-like domains, fused to a variable Ig domain from heavy-chain-only
antibodies (VHH) as adhesion module. The E-tag and myc-tag epitopes
flanking the VHH domain are also indicated. Model of a SA fusion protein
(right) in the bacterial outer membrane (OM) with the VHH exposed
to the extracellular milieu. (b) Flow cytometry analysis of IPTG-induced E. coli EcM1 bearing pNeae (control), pNVgfp, or pNVfib
plasmids. Histograms show the fluorescence intensity of bacteria stained
with anti-myc mAb and secondary anti-mouse IgG-Alexa 488. (c) Induced E. coli EcM1 expressing the Neae polypeptide control (pNeae)
or SAs against GFP (pNVgfp) or human fibrinogen (pNVfib) were incubated
with plastic surfaces coated with GFP or human fibrinogen (Fib), as
indicated. Bacterial adhesion was assessed by crystal violet staining.
(d) Adhesion of E. coli bacteria to target antigen-coated
plastic surface (as in panel c) observed under the light microscope.