Production of carcinoembryonic antigen (CEA) N-A3 domain in Pichia pastoris by fermentation.
Carcinoembryonic antigen (CEA) is a 180-kDa glycoprotein found on the surface of normal colon and malignant human adenocarcinomas. Recently, a fusion protein containing two of the seven Ig-like domains present in CEA (N and A3) has been constructed and expressed in Pichia pastoris [You, Hefta, Yazaki, Wu and Shively (1998) Anticancer Res. 18, 3193-3201]. Here, we report the generation and selection of a multi-copy clone expressing this fusion protein, the optimization of the shake-flask expression protocol and the upscaled production of CEA N-A3 using fermentation technology. P. pastoris transformants secreting the CEA N-A3 domain were generated by electrotransformation of the GS115 host strain with the pPIC9K vector containing the CEA N-A3 cDNA [You, Hefta, Yazaki, Wu and Shively (1998) Anticancer Res. 18, 3193-3201] then screened for CEA N-A3 expression and G418 resistance. The recombinant CEA N-A3 domain was detected in the culture supernatant using the monoclonal anti-CEA antibody T84.66. Optimization of methanol-induction conditions resulted in a high-methanol shake-flask expression protocol yielding significantly increased CEA N-A3 levels. Fermentation and culture conditions were optimized for 5-l working-volume fermentations and CEA N-A3 was affinity purified using Ni-IDA (imino di-acetic acid) affinity chromatography from the clarified fermentation supernatant. Peptide N-glycosidase F treatment revealed that the recombinant protein was heavily glycosylated but expressed as a single polypeptide of 28 kDa with no evidence of proteolytic degradation. Our results demonstrate that functional CEA N-A3 domain can be produced in sufficient quantities in P. pastoris for structural analysis or diagnostic applications. To our knowledge, this article represents the first report on the production of a human tumour antigen through fermentation.
Hellwig
S
S
Institut für Biologie I (Botanik/Molekulargenetik), RWTH Aachen, D-52074 Aachen, Germany.
Robin
F
F
Drossard
J
J
Raven
N P
NP
Vaquero-Martin
C
C
Shively
J E
JE
Fischer
R
R
D001483:Base Sequence; D002272:Carcinoembryonic Antigen / Q000096:biosynthesis* / Q000235:genetics / Q000302:isolation & purification; D002846:Chromatography, Affinity; D003001:Cloning, Molecular; D017931:DNA Primers; D004591:Electrophoresis, Polyacrylamide Gel; D004797:Enzyme-Linked Immunosorbent Assay; D005285:Fermentation; D006031:Glycosylation; D006801:Humans; D010843:Pichia / Q000235:genetics*; D011994:Recombinant Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D020349:Surface Plasmon Resonance; D014170:Transformation, Genetic
D002272:Carcinoembryonic Antigen; D017931:DNA Primers; D011994:Recombinant Proteins