High-level expression of human tumour suppressor P53 in the methylotrophic yeast: Pichia pastoris

The human tumour suppressor P53 is a key protein involved in tumour suppression. P53 acts as a “guardian of genome” by regulating many target genes involved in cell cycle regulation, DNA repair and apoptosis. We report the P53 expression by the methylotrophic yeast Pichia pastoris using the methanol inducible AOX1 promoter. We have produced the rP53 in intracellular form as well as secreted using the Saccharomyces cerevisiae α-mating factor prepro-leader sequence in two genetic contexts of Pichia, Muts and Mut+. The intracellular P53 was successfully produced by Muts (KM71) as well as Mut+ (X33) strains, however, the secreted form was mainly observed in the Muts strain, despite a higher number of p53 copies integrated in the Mut+ strain. Interestingly, in Muts phenotype, the medium pH influences markedly the rP53 production since it was higher at pH 7 than 6.