Noncanonical Amino Acid
Labeling in Vivo to Visualize
and Affinity Purify Newly Synthesized Proteins in Larval Zebrafish
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Abstract
Protein expression in the nervous system undergoes regulated
changes
in response to changes in behavioral states, in particular long-term
memory formation. Recently, methods have been developed (BONCAT and
FUNCAT), which introduce noncanonical amino acids bearing small bio-orthogonal
functional groups into proteins using the cells’ own translational
machinery. Using the selective “click reaction”, this
allows for the identification and visualization of newly synthesized
proteins in vitro. Here we demonstrate that noncanonical amino acid
labeling can be achieved in
vivo in an intact organism capable of simple learning behavior, the
larval zebrafish. We show that azidohomoalanine is metabolically incorporated
into newly synthesized proteins, in a time- and concentration-dependent
manner, but has no apparent toxic effect and does not influence simple
behaviors such as spontaneous swimming and escape responses. This
enables fluorescent labeling of newly synthesized proteins in whole
mount larval zebrafish. Furthermore, stimulation with a GABA antagonist
that elicits seizures in the larval zebrafish causes an increase in
protein synthesis throughout the proteome, which can also be visualized
in intact larvae