SYNTHETIC APPROACHES FOR THE EFFICIENT PREPARATIONS OF HISTONE PROTEINS

Posttranslational modifications (PTMs) of histones play important roles in regulating chromatin structure, transcription, and DNA damage repair. Each of the four histones H2B, H2A, H3, H4 undergoes multiple PTMs. However little is known about the effects of these modifications at the molecular level. Thus there is an urgent need for general methods to rapidly access these bioconjugates for various studies. In this regard, chemical protein synthesis offers unique opportunities to prepare these conjugates in high purity, homogeneity and workable quantities.

Chemical synthesis of complex proteins from several peptide fragments using native chemical ligation (NCL) could be achieved in stepwise, one-pot, convergent or on solid support. In NCL, purification and lyophilization steps are often required after each ligation step, which prolong the time of synthesis and reduce significantly the final yield. Solid phase chemical ligation (SPCL), in principle, overcome these limitations and facilitates the synthesis of histone proteins in good yields. We have also investigated two other methods (one-pot & convergent) in more complex systems such as H2B that is ubiquitinated at Lys34, Lys120, glycosylated at Ser112, and doubly modified with ubiquitin and N-acetylglucosamine. This study demonstrated that the applied convergent strategy for the synthesis of most of these complex targets is better than the one-pot approach in terms of yield and purity. In this poster, we will present these different synthetic strategies and their utilities in the synthesis of these complex targets.

[1]M. Jbara, M. Seenaiah, A. Brik, Chem. Commun. 2014, 50, 12534-12537.

[2]M. Seenaiah, M. Jbara, S. M. Mali, A. Brik, Angew. Chem. Int. 2015 DOI: 10.1002/anie.201503309.