Isopeptag
Encyclopedia
Isopeptag is a 16 amino acid peptide tag that can be genetically linked to proteins without interfering with protein folding. What makes the isopeptag different from other peptide tags is that it can bind its binding protein through a permanent and irreversible covalent bond. Other peptide tags generally bind their targets through weak non-covalent interactions, thus limiting their use in applications where molecules experience extreme forces. The isopeptags covalent binding to its target overcomes these barriers and allows target proteins to be studied in harsher molecular environments.
protein (Spy0128) from Streptococcus pyogenes. Spy0128 contains two intramolecular isopeptide bond
s , and to generate the isopeptag one of these bonds was split by removing the last β-sheet in the protein.
. The reaction is robust and occurs at various temperatures from 4-37°C, a pH range of 5-8, and in the presence of commonly used detergents. Also, the reaction is independent of the redox state of the environment and can occur equally well in both reducing and oxidizing conditions.
Development
The isopeptag was developed by dissecting the pilinPilin
Pilin refers to a class of fibrous proteins that are found in pilus structures in bacteria. Bacterial pili are used in the exchange of genetic material during bacterial conjugation, and a short pilus called a fimbrium is used as a cell adhesion mechanism. Although not all bacteria have pili or...
protein (Spy0128) from Streptococcus pyogenes. Spy0128 contains two intramolecular isopeptide bond
Isopeptide bond
An isopeptide bond is an amide bond that is not present on the main chain of a protein. The bond forms between the carboxyl terminus of one protein and the amino group of a lysine residue on another protein....
s , and to generate the isopeptag one of these bonds was split by removing the last β-sheet in the protein.
Mode of Action
When the isopeptag is bound to a target protein, it spontaneously binds its binding partner through an isopeptide bondIsopeptide bond
An isopeptide bond is an amide bond that is not present on the main chain of a protein. The bond forms between the carboxyl terminus of one protein and the amino group of a lysine residue on another protein....
. The reaction is robust and occurs at various temperatures from 4-37°C, a pH range of 5-8, and in the presence of commonly used detergents. Also, the reaction is independent of the redox state of the environment and can occur equally well in both reducing and oxidizing conditions.