Study proposes system to produce endotoxin-free recombinant proteins

Researchers have developed a novel, cost-effective bacterial system for production of fully endotoxin-free recombinant proteins.

Lipopolysaccharides (LPS)-deficient Acinetobacter baumannii was used for the purification of recombinant proteins. Positively, conducting an assay test demonstrated an ability to suppress viral infection.

The team shared in their paper that there is “ample scope for enhancing the yield of recombinant proteins” yet currently, this is lower than that of existing E. coli expression systems.

Kamoshida et al. remarked that for investigations assessing target proteins expressed and purified in E. coli, “minimal consideration is given to LPS contamination”.

Heavy chain antibody variable domain (VHH) antibodies and endotoxin testing

VHH antibodies are amenable to bacterial production due to their “small size and lack of glycosylation sites”, according to Kamoshida et al.

When compared with typical antibodies, these antibodies are more stable, have a higher ability to maintain activity in adverse conditions and are easily modifiable via protein engineering techniques. Overall, these properties position VHH antibodies with “great potential for commercial applications,” the paper highlighted.

While VHH antibodies are “usually difficult to express in E. coli”, the system applied in the study facilitated production of the multispecific VHH rheumatoid arthritis drug ozoralizumab. Like “many biopharmaceuticals”, this drug is produced using “Chinese hamster ovarian cells as a host organism”, resulting in high production costs, the paper explained.

They further proposed using the colistin-resistant A. baumannii. KL037S strain “as a host for endotoxin-free recombinant protein production for pharmaceuticals”.

Advancing production of recombinant proteins

Kamoshida et al. concluded that “the secretion ability of the expression system, although requiring large-scale handling, is relatively simple and thus amenable to automation using a perfusion culture, with the potential for industrial applications”.

Looking to the future, the team suggested the proposed approach is applicable in scenarios such as regenerative medicine, where “even minimal endotoxin contamination can pose problems”.

This paper was published in PNAS Nexus.