DsbC

Disulfide bonds are crucial for the structural stability and biological activity of many proteins. These covalent linkages between cysteine residues help maintain the native conformation of proteins, especially those secreted or located in the outer membrane. However, the formation of correct disulfide bonds in recombinant proteins can be challenging, particularly in bacterial expression systems like Escherichia coli (E. coli).

Disulfide-bond isomerases are enzymes that facilitate the formation and rearrangement of disulfide bonds in proteins. One of the well-known disulfide-bond isomerases is DsbC, which is particularly effective in ensuring the correct formation of disulfide bonds in proteins with multiple cysteine residues . DsbC works by rearranging incorrectly formed disulfide bonds to their native configuration, thus ensuring the proper folding and functionality of the protein .

The production of recombinant proteins containing disulfide bonds in E. coli is often challenging due to the reducing environment of the bacterial cytoplasm, which is not conducive to disulfide bond formation. To overcome this, several strategies have been developed:

1. Targeting to the Periplasm: Proteins can be directed to the periplasmic space of E. coli, which has an oxidizing environment suitable for disulfide bond formation .
2. Co-expression Systems: Systems like CyDisCo (Cytoplasmic Disulfide bond formation in E. coli) co-express a protein of interest along with a sulfhydryl oxidase and a disulfide bond isomerase, enabling the formation of disulfide bonds even in the reducing cytoplasm .
3. Fusion Partners: Using fusion partners like DsbC can enhance the solubility and correct folding of disulfide-rich proteins in E. coli .