Effect and mechanism of signal peptide and maltose on recombinant type III collagen production in Pichia pastoris.

Recombinant type III collagen plays an important role in cosmetics, wound healing, and tissue engineering. Thus, increasing its production is necessary. After an initial increase in output by modifying the signal peptide, we showed that adding 1% maltose directly to the medium increased the yield and reduced the degradation of recombinant type III collagen. We initially verified that Pichia pastoris GS115 can metabolize and utilize maltose. Interestingly, maltose metabolism-associated proteins in Pichia pastoris GS115 have not yet been identified. RNA sequencing and transmission electron microscopy were performed to clarify the specific mechanism of maltose influence. The results showed that maltose significantly improved the metabolism of methanol, thiamine, riboflavin, arginine, and proline. After adding maltose, the cell microstructures tended more toward the normal. Adding maltose also contributed to yeast homeostasis and methanol tolerance. Finally, adding maltose resulted in the downregulation of aspartic protease YPS1 and a decrease in yeast mortality, thereby slowing down recombinant type III collagen degradation. KEY POINTS: • Co-feeding of maltose improves recombinant type III collagen production. • Maltose incorporation enhances methanol metabolism and antioxidant capacity. • Maltose addition contributes to Pichia pastoris GS115 homeostasis.