SYSTEM FOR ANTIBODY EXPRESSION AND ASSEMBLY
The present invention provides methods and compositions for expression and production of recombinant antibodies in a host cell system, such as prokaryotic and eukaryotic expression systems. Particularly contemplated are recombinant systems for temporally separated expression of light chain and heavy chain of antibodies. The antibody products including antibody fragments can be used in various aspects of biological research, diagnosis and medical treatment.
1 . A process for producing a functional antibody or fragment thereof in a host cell transformed with two separate translational units respectively encoding the light and heavy chains of said antibody or fragment thereof, comprising the steps of: a) culturing the host cell under suitable conditions so that the light chain and heavy chain are expressed in a sequential fashion, thereby temporally separating the production of the light and heavy chains; and b) allowing the assembly of the light and heavy chains to form the functional antibody or fragment thereof.
2 . The process of claim 1 wherein the host cell is prokaryotic, each translational unit further comprising a nucleotide sequence encoding for a prokaryotic secretion signal or variant thereof operably linked to the N′-terminal of the light or heavy chain.
3 . The process of claim 2 , wherein the two separate translational units are controlled by different promoters.
4 . The process of claim 3 , wherein the two translational units are located on a single recombinant vector.
5 . The process of claim 2 , wherein the secretion signal is selected from the group consisting of STII, OmpA, PhoE, LamB, MBP and PhoA.
6 . The process of claim 5 , wherein the secretion signal is STII.
7 . The process of claim 3 , wherein the promoter for each translational unit is selected from the group consisting of phoA, TacI, TacII, lpp, lac-lpp, lac, ara, trp, trc and T7 promoters.
8 . The process of claim 7 , wherein one promoter is the phoA promoter and the other promoter is the TacII promoter.
9 - 14 . (canceled)
15 . The process of claim 1 , wherein the host cell is a prokaryotic cell from an E. coli strain.
16 . The process of claim 15 , wherein the E. coli strain is genetically engineered to over-express at least one chaperone protein selected from the group consisting of DsbA, DsbC, DsbG and FkpA.
17 . The process of claim 15 , wherein the E. coli strain is deficient for endogenous protease activities.
18 . The process of claim 15 , wherein the genotype of the E. coli strain contains Δprc prc-suppressor.
19 . The process of claim 1 , wherein the heavy chain of the antibody is full length.
20 . The process of claim 19 , wherein the light chain is expressed first and the full length heavy chain is subsequently expressed.
21 . A system for sequential expression of a light chain and a heavy chain of an antibody or fragment thereof, comprising a host cell transformed with a recombinant vector, said vector comprising two separate translational units respectively encoding the light chain and heavy chain, each translational unit operably linked to a different promoter, wherein under suitable conditions, the activation of the two translational units are temporally separated, thereby allowing the sequential expression of the light chain and the heavy chain.
22 - 25 . (canceled)
26 . The system of claim 21 , wherein each translational unit is operably linked to a different inducible promoter.
27 - 34 . (canceled)
35 . The system of claim 21 , wherein the host cell is a prokaryotic cell from an E. coli strain.
36 . The system of claim 35 , wherein the E. coli strain is genetically engineered to over-express at least one chaperone protein selected from the group consisting of DsbA, DsbC, DsbG and FkpA.
37 . The system of claim 35 , wherein the E. coli strain is deficient for endogenous protease activities.
38 - 40 . (canceled)
41 . A recombinant vector for production of a functional antibody or fragment thereof in a host cell, said vector comprising a) a first promoter preceding a first translational unit encoding a secretion signal operably linked to a light chain and b) a second promoter preceding a second translational unit encoding a secretion signal operably linked to a heavy chain, said first and second promoters are inducible under different conditions.
42 - 57 . (canceled)