Engineering a methyllysine reader with photoactive amino acid in mammalian cells

Abstract

Methyllysine sites in proteins are recognized by an array of reader domains that mediate protein–protein interactions for controlling cellular processes. Herein, we engineer a chromodomain, an essential methyllysine reader, to carry 4-azido-L-phenylalanine (AzF) via amber suppressor mutagenesis and demonstrate its potential to bind and crosslink methylated proteins in human cells. We further develop a first-of-its kind chromodomain variant bearing two AzF units with enhanced crosslinking potential suitable for profiling the transient methyllysine interactome.