Isolation of the Pichia pastoris glyceraldehyde-3-phosphate dehydrogenase gene and regulation and use of its promoter

We report the cloning and sequence of the glyceraldehyde-3-phosphate dehydrogenase gene (GAP) from the yeast Pichia pastoris. The gene is predicted to encode a 35.4-kDa protein with significant sequence similarity to glyceraldehyde-3-phosphate dehydrogenases from other organisms. Promoter studies in P. pastoris using bacterial β-lactamase as a reporter showed that the GAP promoter (PGAP) is constitutively expressed, although its strength varies depending on the carbon source used for cell growth. Expression of β-lactamase under control of PGAP in glucose-grown cells was significantly higher than under control of the commonly employed alcohol oxidase 1 promoter (PAOX1) in methanol-grown cells. As an example of the use of PGAP, we showed that β-lactamase synthesized under transcriptional control of PGAP is correctly targeted to peroxisomes by addition of either a carboxy-terminal or an amino-terminal peroxisomal targeting signal. PGAP has been successfully utilized for synthesis of heterologous proteins from bacterial, yeast, insect and mammalian origins, and therefore is an attractive alternative to PAOX1 in P. pastoris.