Fate of the UPR marker protein Kar2/Bip and autophagic processes in fed-batch cultures of secretory insulin precursor producing Pichia pastoris.

Background: Secretory recombinant protein production with Pichia (syn. Komagataella) pastoris is commonly associated with the induction of an unfolded protein response (UPR) usually apparent through increased intracellular levels of endoplasmic reticulum (ER) resident chaperones such as Kar2/Bip. During methanol-induced secretory production of an insulin precursor (IP) under industrially relevant fed-batch conditions the initially high level of intracellular Kar2/Bip after batch growth on glycerol unexpectedly declined in the following methanol fed-batch phase misleadingly suggesting that IP production had a low impact on UPR activation.

Decrease of UPR- and ERAD-related proteins in Pichia pastoris during methanol-induced secretory insulin precursor production in controlled fed-batch cultures.

Background: Pichia pastoris is a popular yeast preferably employed for secretory protein production. Secretion is not always efficient and endoplasmic retention of proteins with aberrant folding properties, or when produced at exaggerated rates, can occur. In these cases production usually leads to an unfolded protein response (UPR) and the induction of the endoplasmic reticulum associated degradation (ERAD).

Physiological response of Pichia pastoris GS115 to methanol-induced high level production of the Hepatitis B surface antigen: catabolic adaptation, stress responses, and autophagic processes.

Background: Pichia pastoris is an established eukaryotic host for the production of recombinant proteins. Most often, protein production is under the control of the strong methanol-inducible aox1 promoter. However, detailed information about the physiological alterations in P.