Sequential α-Ketoacid-Hydroxylamine (KAHA) Ligations: Synthesis of C-Terminal Variants of the Modifier Protein UFM1

摘要

The role of conjugation and deconjugation of modifier proteins, such as ubiquitin and SUMO, to their targets has rapidly emerged as one of the most exciting areas of molecular biology and drug discovery. The development of new therapeutics perturbing these regulatory pathways requires access to labeled and derivatized modifier proteins and a means to prepare their conjugates.In some cases, the modifier protein, the target protein, and the specific ligases can be obtained from natural sources but research is increasingly turning to synthetic methods to prepare them and study their biological roles.In this regard, the native chemical ligation (NCL) of C-terminal modifier protein thioesters to a 5-thiolysine residue in a protein stands out for its promise to impact this area. The unnatural 5-thiolysine residue can be incorporated into a target protein by total chemical synthesis, emi-synthesis from expressed protein segments or by ribosomal incorporation. It has already been used to attach ubiquitin to α-synuclein and SUMO and to prepare di-, tri-,and tetra-ubiquitins.