The cover picture shows a journey from garlic to genetic code engineering: In this issue, Budisa and co-workers report in vivo-specific protein olefination with
S-allylcysteine (Sac), which is naturally abundant in garlic. Alternatively, it can also be biosynthesized in situ by supplementing the
amino acid metabolism of
E. coli with allylmercaptan. Sac is recognized and activated by the novel and unique pyrrolysyl-tRNA synthetase-based enzyme
S-allylcysteinyl-tRNA synthetase (SacRS), which is capable of specifically accepting a small, polar
amino acid instead of the long and bulky aliphatic natural substrate. In this way, a biochemical pathway for the production of proteins containing
S-allylcysteine as a minimal tag or label for chemical protein modification has been established. More information can be found in the communication by S. Panke, N. Budisa et al. on
page 85 in Issue 1, 2017 (DOI:
10.1002/cbic.201600537).
