Pichia pastoris glyceraldehyde-3-phosphate dehydrogenase (GAP/GAPDH) promoter
Glyceraldehyde-3-phosphate dehydrogenase (GAP/GAPDH) promoter from the methylotrophic yeast Pichia pastoris (Komagataella phaffii); drives strong constitutive transcription on glucose without methanol induction. Used as an alternative to the inducible AOX1 promoter when continuous, carbon-source-independent expression is preferred over tight regulatory control.
Origin: Pichia pastoris (Komagataella phaffii)
Characteristics
Constitutively transcribed from the native GAP promoter of the glycolytic GAPDH gene; active on glucose, glycerol, and methanol carbon sources, unlike the AOX1 promoter, which is repressed by glucose and glycerol and induced only by methanol (Waterham et al. 1997). Expression driven from the GAP promoter on glucose reaches levels comparable to methanol-induced AOX1 promoter activity, but drops when glycerol or methanol is used as the sole carbon source (Vogl and Glieder 2013).
Applications: Used for continuous, high-level heterologous protein production in Pichia pastoris shake-flask and fermenter cultures, including secreted industrial enzymes such as Rhizomucor miehei lipase, avoiding the methanol feeding and associated handling costs required by AOX1-driven expression (He et al. 2015).
Limitations: Cannot be turned off or tuned by withholding an inducer, so it is a poor choice for genes whose product is toxic or growth-inhibiting to the host cell. Constitutive high-level synthesis throughout the growth phase also adds metabolic burden that methanol-induced AOX1 expression avoids during early biomass accumulation.