Abstract: Described herein is a protein display selection method which uncouples a protein of interest (POI) library from the display selection system. Display of the POI can be achieved by forming a covalent bond between the POI and the anchor protein post expression either by enzymatic protein ligation (e.g. SpyLigase, SnoopLigase, sortase, butelase, peptiligase etc.) or by spontaneous covalent bond formation (e.g. SpyTag/SpyCatcher, SnoopTag/SnoopCatcher, etc.). The POI library is fused to a tethering sequence, for example SpyTag, at the C-terminus of the POI which then forms a covalent bond to a capture sequence found on an anchor protein, for example, the SpyCatcher-fused anchor protein, e.g., a SpyCatcher-geneIII protein (SpyCatcher-pIII) fusion, for the most common form of phage display. Nucleic acid constructs, host cell systems and methods of producing the protein display systems are also provided.

Abstract: Periplasmic fusion proteins comprising a binding motif attached to a C-terminus of a first protein or embedded within an amino acid sequence of the first protein, nucleic acid constructs encoding the periplasmic fusion proteins, vectors comprising the nucleic acid constructs, and methods of producing the periplasmic fusion proteins are provided. Also provided are protease deficient host cells for producing the periplasmic fusion proteins.

Abstract: Described herein is a protein display selection method which uncouples a protein of interest (POI) library from the display selection system. Display of the POI can be achieved by forming a covalent bond between the POI and the anchor protein post expression either by enzymatic protein ligation (e.g. SpyLigase, SnoopLigase, sortase, butelase, peptiligase etc.) or by spontaneous covalent bond formation (e.g. SpyTag/SpyCatcher, SnoopTag/SnoopCatcher, etc.). The POI library is fused to a tethering sequence, for example SpyTag, at the C-terminus of the POI which then forms a covalent bond to a capture sequence found on an anchor protein, for example, the SpyCatcher-fused anchor protein, e.g., a SpyCatcher-geneIII protein (SpyCatcher-pIII) fusion, for the most common form of phage display. Nucleic acid constructs, host cell systems and methods of producing the protein display systems are also provided.