Systematic Evaluation of Bioorthogonal Reactions in Live Cells with Clickable HaloTag Ligands: Implications for Intracellular Imaging
作者:Heather E. Murrey、Joshua C. Judkins、Christopher W. am Ende、T. Eric Ballard、Yinzhi Fang、Keith Riccardi、Li Di、Edward R. Guilmette、Joel W. Schwartz、Joseph M. Fox、Douglas S. Johnson
DOI:10.1021/jacs.5b06847
日期:2015.9.9
Bioorthogonal reactions, including the strain-promoted azide-alkyne cycloaddition (SP.AAC) and inverse electron demand Diels-Alder (iEDDA) reactions, have become increasingly popular for live-cell imaging applications. However, the stability and reactivity of reagents has never been systematically explored in the context of a living cell. Here we report a universal, organelle-targetable system based on HaloTag protein technology for directly comparing bio-orthogonal reagent reactivity, specificity, and stability using clickable HaloTag ligands in various subcellular compartments. This system enabled a detailed comparison of the bioorthogonal reactions in live cells and informed the selection of optimal reagents and conditions for live-cell imaging studies. We found that the reaction of sTCO with monosubstituted tetrazines is the fastest reaction in cells; however, both reagents have stability issues. To address this, we introduced a new variant of sTCO, Ag-sTCO, which has much improved stability and can be used directly in cells for rapid bioorthogonal reactions with tetrazines. Utilization of Ag complexes of conformationally strained trans-cyclooctenes should greatly expand their usefulness especially when paired with less reactive, more stable tetrazines.