Comparing cytosolic expression to peroxisomal targeting of the chimeric L1/L2 (ChiΔH-L2) gene from human papillomavirus type 16 in the methylotrophic yeasts Pichia pastoris and Hansenula polymorpha.

The chimeric ChiΔH-L2 gene from human papillomavirus type 16, consisting of structural proteins L1 and L2, was successfully expressed in the cytosol of both Pichia pastoris and Hansenula polymorpha during methanol induction. In addition, a novel approach was employed whereby ChiΔH-L2 was targeted to the peroxisome using peroxisomal targeting sequence 1 (PTS1) to compare ChiΔH-L2 yields in the peroxisome vs the cytosol. The ChiΔH-L2 gene was yeast-optimized and cloned into plasmids aimed at genomic integration. Levels of intracellular ChiΔH-L2 accumulation in the cytosol were highest in P. pastoris KM71 strain KMChiΔH-L2 (1.43 mg/l), compared to the maximum production level of 0.72 mg/l obtained with H. polymorpha. ChiΔH-L2 targeting to the peroxisome was successful; however, it appeared to negatively affect ChiΔH-L2 production in both P. pastoris and H. polymorpha.