Use of Serine/Threonine Ligation for the Total Chemical Synthesis of HMGA1a Protein with Site-Specific Lysine Acetylations.

High-mobility-group (HMG) proteins are a class of abundant non-histone nuclear proteins, among which HMGA1a is well-known for its association with transcription regulation as well as tumor formation and disease development. To study the functions of post-translational modifications, homogeneous HMGA1a protein with site-specific lysine acetylations (64/66/70/73) has been chemically synthesized. The full-length HMGA1a protein was assembled through two Ser/Thr ligations of three peptide fragments at Gly37-Thr37 and Thr75-Thr76 sites, respectively. Further in vitro studies with chemically synthesized proteins suggested that these acetylations did not significantly affect the CK2-catalyzed phosphorylation on the HMGA1a acidic tail.