Photocatalytic Proximity Labelling of MCL-1 by a BH3 Ligand

19 March 2019, Version 1
This content is a preprint and has not undergone peer review at the time of posting.

Abstract

Ligand-directed protein labelling can be used to introduce diverse chemical functionalities onto proteins without the need for incorporation of genetically encoded tags. Here we report a method for the rapid and efficient labelling of a protein using a ruthenium-bipyridyl (Ru(II)(bpy)3) modified peptide designed to mimic an interacting BH3 ligand within a BCL-2 family protein-protein interaction (PPI). Using sub-stoichiometric quantities of (Ru(II)(bpy)3)-modified NOXA-B and irradiation with visible light for 1 minute, the anti-apoptotic protein MCL-1 was photolabelled in a ligand-dependent manner with a variety of functional tags, as determined by in-gel fluorescence, affinity purification, and ESIMS analysis. In contrast with previous reports on Ru(II)(bpy)3-catalysed photolabelling, tandem MS experiments revealed that the dominant labelling occurred on a cysteine residue of MCL-1. Labelling of MCL-1 occurred selectively in mixtures with other proteins, including the structurally related BCL-2 member, BCL-xL. These results improve methodology for proximity-induced photolabelling of proteins, demonstrate the approach is applicable to interfaces that mediate PPIs, and pave the way towards future use of ligand-directed proximity labelling for dynamic analysis of the localisation and interactome of BCL-2 family proteins.

Keywords

ruthenium complexes
peptide binding groove
BCL-2 family
photolabelling
protein-protein interactions
ligand-directed labelling
proximity labelling
MCL-1
single electron transfer

Comments

Comments are not moderated before they are posted, but they can be removed by the site moderators if they are found to be in contravention of our Commenting Policy [opens in a new tab] - please read this policy before you post. Comments should be used for scholarly discussion of the content in question. You can find more information about how to use the commenting feature here [opens in a new tab] .
This site is protected by reCAPTCHA and the Google Privacy Policy [opens in a new tab] and Terms of Service [opens in a new tab] apply.