[Effect of disruption of Pichia pastoris YPS1 gene on viability and production of recombinant proteins].

In the present study, we constructed a Pichia pastoris mutant strain PS111 that lacks one member of the yapsin family through disruption of the YPS1 gene coding for aspartic protease yapsin 1. Under normal growth conditions, the PS111 mutant strain did not show detectable growth defects. Unlike the S. cerevisiaeyps1 mutant, the P. pastoris PS111 strain showed no sensitivity when grown in the presence of CaCl2, elevated temperature (37 degrees C), under acid (pH 4.9) and alkaline (pH 8.3) conditions. Unlike the S. cerevisiae, the P. pastoris yps1 mutant showed decreased growth phenotype induced by cell wall-perturbing reagent sodium dodecyl sulfate (SDS) only when the concentration of SDS was increased by ten times. The use of the yps1 disruptant to produce human interferon alpha 16 (hINF-alpha 16) prevents proteolysis, which occurs in the wild-type strain. It was found that the degradation of recombinant protein Alburon composed of human serum albumin (HSA) and hINF-alpha 16 was slightly decreased in the strain lacking yapsin 1.