Intramolecular energy transfer to S-nitrosylated Cys residues is at the basis of fluorescence sensitivity to nitric oxide in the blue fluorescent protein mTagBFP2

Fluorescent protein (FP) variants have recently emerged as promising intracellular nitric oxide (NO) sensors based on NO-induced fluorescence loss due to cysteine S-nitrosylation - the covalent addition of a nitroso group to a cysteine thiol within a protein to form an S-nitrosothiol. Here, we investigate the mechanisms underlying this fluorescence loss using a combined experimental and computational approach. We focus on mTagBFP2, a blue fluorescent protein that undergoes a 70% reduction in flu