Temperature shift for high yield expression of polypeptides in yeast and other transformed cells
Methods for producing heterologous proteins are disclosed. In particular, the present disclosure provides improved methods of producing desired proteins, including multi-subunit proteins such as antibodies, with a higher yield and improved purity. In exemplary embodiments, the transformed cells are a yeast, e.g., methylotrophic yeast such as Pichia pastoris.
1. A method of producing a desired full-length antibody, wherein the expression of the desired full-length antibody occurs in both step (a) and step (b) comprising:
(a) wherein step (a) comprises culturing Pichia pastoris yeast cells comprising genes that provide for the expression of said desired full-length antibody at a first temperature which is between 27 degrees C. and 30 degrees C. inclusive; and
(b) after step (a), step (b) comprises culturing the same Pichia pastoris yeast cells which are cultured in step (a) at a second temperature which is between 1 degree C. and 3 degrees C. inclusive higher than said first temperature and allowing said same culture of Pichia pastoris yeast cells to continue to produce said desired full-length antibody;
wherein
(i) culture step (a) and step (b) are effected after an inoculum expansion step;
(ii) said desired full-length antibody is expressed under control of a non-temperature inducible promoter;
(iii) said Pichia pastoris yeast cells comprise between 1-10 copies of a gene encoding the heavy chain of said desired full-length antibody and between 1-10 copies of a gene encoding the light chain of said desired full-length antibody;
(iv) culture steps (a) and (b) comprise a batch phase followed by a fed batch phase, wherein culture step (a) is initiated during the batch phase and culture step (b) is initiated during the batch phase, during of the fed batch phase, or between the batch phase and the fed batch phase;
(v) culture step (a) and step (b) comprise detecting a concentration of dissolved oxygen in the culture of Pichia pastoris yeast cells;
(vi) said second temperature is effected after a rapid increase in the concentration of dissolved oxygen is detected in the culture; and
(vii) said method increases the yield of said desired full-length antibody and/or decreases the relative abundance of full-length antibody complexes having aberrant disulfide bonds relative to the same culture method effected without a difference between said first temperature and said second temperature.
2. The method of claim 1 , wherein: (i) said first temperature is between 27 degrees C. and 28.5 degrees C. or (ii) said first temperature is between 27.5 degrees C. and 28.5 degrees C. inclusive.
3. The method of claim 1 , wherein;
(i) said method further decreases the relative abundance of one or more product-associated variants relative to the same method effected without a difference between said first temperature and said second temperature; and/or
(ii) said method decreases the relative abundance of product-associated variants having a higher or lower apparent molecular weight than said desired multi-subunit complex as detected by size exclusion chromatography or gel electrophoresis relative to the same method effected without a difference between said first temperature and said second temperature and/or
(iii) said method decreases the relative abundance of complexes having aberrant disulfide bonds relative to the same method effected without a difference between said first temperature and said second temperature; and/or
(iv) said method decreases the relative abundance of complexes having reduced cysteines relative to the same method effected without a difference between said first temperature and said second temperature; and/or
(v) said method decreases the relative abundance of complexes having aberrant glycosylation relative to the same method effected without a difference between said first temperature and said second temperature.
4. The method of claim 1 , wherein said Pichia pastoris yeast cells comprise polyploidal Pichia pastoris yeast cells.
5. The method of claim 4 , wherein the genes that provide for expression of said desired full-length antibody are integrated into one or more genomic loci.
6. The method of claim 1 , wherein step (a) comprises culturing said Pichia pastoris yeast cells in a culture medium comprising glycerol as a carbon source until said glycerol is exhausted.
7. The method of claim 1 , wherein said desired full-length antibody is expressed under control of a promoter selected from the group consisting of: the CUP I, AOX1, ICLI, glyceraldehyde-3-phosphate dehydrogenase (GAP), FLDI, ADH1, alcohol dehydrogenase II, GAL4, PHO3, PHO5, and Pyk promoters, tetracycline inducible promoters, thiamine inducible promoters, chimeric promoters derived therefrom, yeast promoters, mammalian promoters, insect promoters, plant promoters, reptile promoters, amphibian promoters, viral promoters, and avian promoters.
8. The method of claim 1 , wherein said yeast cell is a diploid, tetraploid, or polyploid Pichia pastoris cell.
9. The method of claim 1 , further comprising purifying said desired full-length antibody from said Pichia pastoris yeast cells or from the culture medium or from an intracellular component, cytoplasm, nucleoplasm, or a membrane of said yeast cells.
10. The method of claim 1 , wherein said batch phase comprises culturing the yeast cell in a medium comprising a carbon source.
11. The method of claim 10 , wherein the end of said batch phase is determined by exhaustion of the carbon source in the culture medium.
12. The method of claim 1 , wherein the respiratory quotient (RQ) is maintained at a specified value or in a specified range during step (b), wherein (i) said specified RQ value is 1.12 or (ii) said specified RQ range is 1.0 to 1.24, or 1.06 to 1.18, or 1.09 to 1.15, or (iii) said RQ value or RQ range is maintained by modulating one or more of the feed rate, feed composition, supplied air flow rate, agitation rate, and/or oxygen concentration of supplied air.
13. The method of claim 1 , wherein said first temperature is between 27.5° C. and 28.5° C. inclusive, and said second temperature is between 30° C. and 31 º C inclusive.
14. The method of claim 11 , wherein initiation of said second temperature is effected after a rapid increase in the concentration of dissolved oxygen is detected in the culture during the batch phase, during of the fed batch phase, or between the batch phase and the fed batch phase.
15. The method of claim 1 , wherein said second temperature is (i) between 30 degrees C. and 33 degrees C. inclusive or (ii) said second temperature is between 30 degrees C. and 32 degrees C. inclusive or (iii) said second temperature is between 30 degrees C. and 31.5 degrees C. inclusive or (iv) said second temperature is between 30 degrees C. and 31 degrees C. inclusive.
16. The method of claim 1 wherein the respective number of copies of the gene encoding the heavy chain of said antibody and the number of copies of the gene encoding the light chain of said antibody in said cells may be: 2 and 2, 2 and 3, 3 and 3, 3 and 4, 3 and 5, 4 and 3, 4 and 4, 4 and 5, 4 and 6, 5 and 4, 5 and 5, 5 and 6, or 5 and 7.
17. The method of claim 1 wherein the respective number of copies of the gene encoding the heavy chain of said antibody and the number of copies of the gene encoding the light chain of said antibody in said cells may be: 2 and 1, 3 and 1, 4 and 1, 5 and 1, 6 and 1, 7 and 1, 8 and 1, 9 and 1, 10 and 1, 1 and 2, 2 and 2, 3 and 2, 4 and 2, 5 and 2, 6 and 2, 7 and 2, 8 and 2, 9 and 2, 10 and 2, 1 and 3, 2 and 3, 3 and 3, 4 and 3, 5 and 3, 6 and 3, 7 and 3, 8 and 3, 9 and 3, 10 and 3, 1 and 4, 2 and 4, 3 and 4, 4 and 4, 5 and 4, 6 and 4, 7 and 4, 8 and 4, 9 and 4, 10 and 4, 1 and 5, 2 and 5, 3 and 5, 4 and 5, 5 and 5, 6 and 5, 7 and 5, 8 and 5, 9 and 5, 10 and 5, 1 and 6, 2 and 6, 3 and 6, 4 and 6, 5 and 6, 6 and 6, 7 and 6, 8 and 6, 9 and 6, 10 and 6, 1 and 7, 2 and 7, 3 and 7, 4 and 7, 5 and 7, 6 and 7, 7 and 7, 8 and 7, 9 and 7, 10 and 7, 1 and 8, 2 and 8, 3 and 8, 4 and 8, 5 and 8, 6 and 8, 7 and 8, 8 and 8, 9 and 8, 10 and 8, 1 and 9, 2 and 9, 3 and 9, 4 and 9, 5 and 9, 6 and 9, 7 and 9, 8 and 9, 9 and 9, 10 and 9, 1 and 10, 2 and 10, 3 and 10, 4 and 10, 5 and 10, 6 and 10, 7 and 10, 8 and 10, 9 and 10, 10 and 10.
18. The method of claim 1 , wherein said first temperature is 28 degrees C. and said second temperature is 30 degrees C. or 31 degrees C.