Figure 1

Overview of pIII and pIX display routes and the four library groups.

(1) Schematic illustration of pIII and pIX phagemids. The scFv-pIII contains an N-terminal pelB signal sequence, while pIX does not. The scFvs are connected to the capsid proteins by a linker (L). A helper phage encodes wt pIII and wt pIX, resulting in LV display as shown. By using modified helper phages that do not encode either wt capsid protein, the sole source of the capsid protein is the scFv-capsid fusion encoded by the phagemids, resulting in HV display of the fusion. (2) pIII and pIX use different translocation mechanisms, SEC and YidC, respectively, for transport from the cytosol (C) to the periplasmic space (PS). Both capsid proteins are integral inner membrane (IM) proteins prior to virion assembly. (3) Post-translational leader processing cleaves the leader on pIII and scFv-pIII in the PS. (4) The virions are released through the outer membrane (OM), resulting in the four libraries.