High-level secretion of biologically active recombinant human macrophage inflammatory protein-1α by the methylotrophic yeast Pichia pastoris

The human CC chemokine macrophage inflammatory protein-1 alpha (MTP-1 alpha) was produced at a high level in Pichia pastoris under transcriptional control of the highly inducible alcohol oxidase 1 promoter. To ensure proper folding and secretion of the recombinant polypeptide, the MIP-1 alpha gene had been fused to the Saccharomyces cerevisiae alpha-factor prepropeptide, As was revealed by analysis of the cell culture supernatant of recombinant Pichia pastoris, MIP-1 alpha was efficiently secreted. Immunoblot analysis of secreted proteins from recombinant clones using a polyclonal antibody directed against MIP-1 alpha revealed an apparent molecular mass of 8 kDa for the recombinant polypeptide. Up to 70 mg of MIP-1 alpha was purified from 1 liter of yeast culture supernatant by a single chromatography step. Biological activity of recombinant MIP-1 alpha was shown in a chemotaxis assay. Here, the polypeptide specifically induced migration of U937 cells expressing the CCR1 (MIP-1 alpha receptor). Also, in competition binding assays the recombinant MIP-1 alpha displayed high affinity binding. (C) 2000 Academic Press.