Thioester bonds between cysteine and glutamine sidechains can form covalent cross-links between polypeptide chains.
- Thioester bonds in complement proteins C3 and C4 are involved in tagging pathogens for destruction by the immune system, via the alternate complement activation pathway.
- Thioester bonds occur in thioester domains (TED) of Gram-positive bacteria, where they are thought to mediate covalent adhesion of bacteria to host cells[1][2]. Many surface proteins of Gram-positive bacteria are predicted to contain TED as well as isopeptide and ester cross-links. This family of proteins is termed TIE proteins for thioester, isopeptide, ester proteins[2]. Examples: 2xi9, 6fwy.
