Optical Control of Translation with a Puromycin Photoswitch

Translation is an elementary cellular process that involves
a large
number of factors interacting in a concerted fashion with the ribosome.
Numerous natural products have emerged that interfere with the ribosomal
function, such as puromycin, which mimics an aminoacyl tRNA and causes
premature chain termination. Here, we introduce a photoswitchable
version of puromycin that, in effect, puts translation under optical
control. Our compound, termed puroswitch, features a
diazocine that allows for reversible and nearly quantitative isomerization
and pharmacological modulation. Its synthesis involves a new photoswitchable
amino acid building block. Puroswitch shows little activity
in the dark and becomes substantially more active and cytotoxic, in
a graded fashion, upon irradiation with various wavelengths of visible
light. In vitro translation assays confirm that puroswitch inhibits translation with a mechanism similar to that of puromycin
itself. Once incorporated into nascent proteins, puroswitch reacts with standard puromycin antibodies, which allows for tracking de novo protein synthesis using western blots and immunohistochemistry.
As a cell-permeable small molecule, puroswitch can be
used for nascent proteome profiling in a variety of cell types, including
primary mouse neurons. We envision puroswitch as a useful
biochemical tool for the optical control of translation and for monitoring
newly synthesized proteins in defined locations and at precise time
points.