Photo-leucine incorporation reveals the target of a cyclodepsipeptide inhibitor of cotranslational translocation.
Photoaffinity labeling is a powerful tool to identify protein targets of biologically active small molecules, yet is often limited by the size, chemical properties, and availability of photoreactive groups. We report an improved synthesis of photo-leucine, a diazirine-based photoreactive analogue of leucine, and demonstrate its incorporation into a cyclodepsipeptide inhibitor of cotranslational translocation. Photoaffinity labeling in a crude membrane fraction, followed by "click chemistry" with a rhodamine-azide reporter, enabled the identification of Sec61alpha, the structural core of the Sec61 translocation channel, as the inhibitor's target.
MacKinnon
Andrew L
AL
Department of Cellular and Molecular Pharmacology, University of California, San Francisco, California 94158, USA.
Garrison
Jennifer L
JL
Hegde
Ramanujan S
RS
Taunton
Jack
J
D047630:Depsipeptides / Q000737:chemistry*; D007930:Leucine / Q000737:chemistry*; D008565:Membrane Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D015394:Molecular Structure; D010777:Photochemistry; D011485:Protein Binding; D021381:Protein Transport; D000069816:SEC Translocation Channels
D047630:Depsipeptides; D008565:Membrane Proteins; D000069816:SEC Translocation Channels; D007930:Leucine