Eukaryotic cell display systems

Abstract

The present invention provides expression vectors and helper display vectors which can be used in various combinations as vector sets for display of polypeptides on the outer surface of eukaryotic host cells. The expression vector of the invention can be used alone for soluble expression without having to change or reengineer the display vectors. The display systems of the invention are particularly useful for displaying a genetically diverse repertoire or library of polypeptides on the surface of yeast cells, and mammalian cells.

1 . A method for displaying a repertoire of polypeptide sequences of interest on eukaryotic host cells, comprising:
 a) introducing at least one expression vector comprising an expression cassette encoding a polypeptide of interest fused in frame to a first adapter sequence, into host cells   b) introducing a helper vector encoding a fusion protein consisting of a second adapter sequence fused to an outer surface anchoring protein expressed by the host cells of (a), and   c) maintaining the host cells under suitable conditions for expression of the proteins encoded by the expression cassette and helper vector wherein the polypeptides of interest are displayed on the surface of the host cell.   
     
     
         2 . The method of  claim 1  wherein the repertoire of polypeptide sequences of interest is an antibody library. 
     
     
         3 . The method of  claim 2  wherein the antibody library is scFv library. 
     
     
         4 . The method of  claim 2  wherein the antibody library is Fab library. 
     
     
         5 . The method of  claim 1  wherein the eukaryotic host cells are yeast cells. 
     
     
         6 . The method of  claim 5  wherein the yeast cells are selected from a group consisting of  S. cerevisiae, P. pichia, H. polymorpha,  and  C. albicans.    
     
     
         7 . The method of  claim 5  wherein the yeast outer surface anchoring sequences are selected from the group consisting of Aga1 and Aga2, Cwp1, Cwp2, Gas1p, Yap3p, Flo1p, Crh2p, Pir1, Pir2, Pir4, Icwp in  S.cerevisiae;  HpSEDI, HpGASI, HpTIPI, HPWPI in  H. polymorpha,  and Hwp1p, Als3p, Rbt5p in  C. albicans.    
     
     
         8 . The method of  claim 1  wherein the eukaryotic host cell is a mammalian cell selected from a group consisting of animal cells and insect cells. 
     
     
         9 . The method of  claim 9  wherein the outer surface anchoring sequences are selected from a group consisting of transmembrane domains of cell surface receptors, GPI anchor sequences, non-cleavable type II signal anchor sequences. 
     
     
         10 . The method of  claim 1  wherein the first adapter and second adapter are homodimer sequences. 
     
     
         11 . The method of  claim 1  wherein the first adapter and second adapter are heterodimer sequences. 
     
     
         12 . The method of  claim 1  wherein the first adapter and second adapter are dimeric sequences consist a pair of cysteine residues. 
     
     
         13 . The method of  claim 12  wherein the first and second adapter sequences are derived from coiled coil domains. 
     
     
         14 . The method of  claim 6  wherein the first adapter sequence consists of SEQ ID NO:1 and the second adapter sequence consists of SEQ ID NO: 2. 
     
     
         15 . The method of  claim 1  wherein the expression vector is selected from pMAT9, pMAT12, pMAT19, pMAG10 and the helper vector is selected from pMAT7, pMAT8, and pMAG2. 
     
     
         16 . A yeast eukaryotic host cell transformed with a helper vector selected from the group pMAT7, or pMAT8. 
     
     
         17 . A mammalian host cell transfected with a helper vector such as pMAG2. 
     
     
         18 . A kit comprising:
 a) at least one expression vector comprising an expression cassette encoding a polypeptide of interest fused in frame to a first adapter sequence, and   b) a helper vector encoding a fusion protein consisting of a second adapter sequence fused to an outer surface anchoring protein.