Production of the bullous pemphigoid antigen 230 (BP230) by Saccharomyces cerevisiae and Pichia pastoris

BP230 is a cytoskeletal linker protein of 2649 amino acids originally identified as the target autoantigen in bullous pemphigoid, a potentially devastating autoimmune skin blistering disorder. To better define its function, we sought to generate recombinant forms of BP230 in both Saccharomyces cerevisiae and Pichia pastoris after cloning its entire cDNA. By immunoblot analysis, full-length BP230 was not found in extracts of P. pastoris, whereas minor amounts of degraded BP230 were detected in extracts of S. cerevisiae. In contrast, both S. cerevisiae and P. pastoris were able to produce the 770-amino acid COOH-terminal domain of BP230. Furthermore, the production level of the recombinant BP230 tail in S. cerevisiae was significantly higher than that observed in P. pastoris and that of endogenous BP230 in cultured human keratinocytes. Finally, 12 of 17 (71%) BP sera recognized the recombinant BP230 protein in yeast extracts. Our results indicate that S. cerevisiae occasionally constitutes a better tool for recombinant protein production than P. pastoris. Although both its large size and poor solubility limit production of BP230, the developed yeast system provides cellular fractions enriched in BP230 recombinant proteins that constitute useful tools for the diagnosis of bullous pemphigoid.