Changes in cellular secretory processing during baculovirus infection

Area of Science:

• Biotechnology
• Molecular Biology
• Insect Cell Culture

Background:

• The baculovirus expression vector system (BEVS) is widely used for producing recombinant proteins.
• Efficient protein folding and processing in the endoplasmic reticulum (ER) are crucial for high-level protein expression.
• Understanding the dynamics of ER molecular chaperones is key to optimizing protein yields in BEVS.

Purpose of the Study:

• To investigate the temporal expression patterns of ER molecular chaperones during recombinant protein production in BEVS.
• To correlate chaperone expression levels with the expression of a model secretory protein, sGFP.
• To elucidate the role of ER chaperones in the maximal expression of exogenous proteins.

Main Methods:

• Utilized the baculovirus expression vector system (BEVS) for recombinant protein expression.
• Quantified transcripts and protein levels of secretory green fluorescent protein (sGFP).
• Monitored the expression of ER molecular chaperones, including Bombyx mori protein disulfide isomerase (bPDI) and calnexin, post-infection (p.i.).

Main Results:

• Secretory green fluorescent protein (sGFP) transcripts were detected from day 2 to day 5 post-infection (p.i.).
• GFP protein expression was observed from day 3 to day 5 p.i.
• Endoplasmic reticulum (ER) chaperone transcripts (bPDI) were present early (day 1 p.i.), but chaperone protein levels (bPDI, calnexin) decreased from day 3 p.i. and were undetectable by day 4 p.i.

Conclusions:

• The expression of ER molecular chaperones is rate-limited during maximal exogenous protein production in BEVS.
• A potential imbalance between protein production and chaperone availability may affect protein yield.
• Optimizing ER chaperone expression could enhance recombinant protein production in BEVS.