Rapid Cross-Metathesis for Reversible Protein Modifications via Chemical Access to Se-Allyl-selenocysteine in Proteins

Yuya A Lin,Omar Boutureira,Bhaskar Bhushan,Lukas Lercher,Benjamin G Davis,Robert S Paton

doi:10.1021/ja403191g

Abstract

Cross-metathesis (CM) has recently emerged as a viable strategy for protein modification. Here, efficient protein CM has been demonstrated through biomimetic chemical access to Se-allyl-selenocysteine (Seac), a metathesis-reactive amino acid substrate, via dehydroalanine. On-protein reaction kinetics reveal a rapid reaction with rate constants of Seac-mediated-CM comparable or superior to off-protein rates of many current bioconjugations. This use of Se-relayed Seac CM on proteins has now enabled reactions with substrates (allyl GlcNAc, N-allyl acetamide) that were previously not possible for the corresponding sulfur analogue. This CM strategy was applied to histone proteins to install a mimic of acetylated lysine (KAc, an epigenetic marker). The resulting synthetic H3 was successfully recognized by antibody that binds natural H3-K9Ac. Moreover, Cope-type selenoxide elimination allowed this putative marker (and function) to be chemically expunged, regenerating an H3 that can be rewritten to complete a chemically enabled “write (CM)–erase (ox)–rewrite (CM)” cycle.

Highlights

D eveloping strategies for site-specific protein modifications is an ongoing challenge in chemical biology.[1−3] For over a decade, allylic alcohols have been identified as reactive in olefin metathesis.[4,5] only in recent years has a generalized allylic heteroatom effect begun to emerge in cross-metathesis (CM).[5]
We show here that installation into peptides and proteins of the simplest amino acid residue containing an allyl selenide moiety, the unnatural amino acid Se-allyl-selenocysteine (Seac), enables rapid and efficient CM
In situ generation of allyl selenolate via cleavage of methyl benzoselenoate 2a failed (Table S1)

Summary

Introduction

D eveloping strategies for site-specific protein modifications is an ongoing challenge in chemical biology.[1−3] For over a decade, allylic alcohols have been identified as reactive in olefin metathesis.[4,5] only in recent years has a generalized allylic heteroatom effect begun to emerge in cross-metathesis (CM).[5]. The generation of an appropriate conjugate, allyl selenolate nucleophile, was explored on model Dha 3 (Scheme 2a).

Results

Conclusion