Lanthanide-Binding Tags for 3D X-ray Imaging of Proteins in Cells at Nanoscale Resolution
Tiffany W. Victor, Katherine H. O’Toole, Lindsey M. Easthon, Mingyuan Ge, R. Smith, Xiaojing Huang, Hanfei Yan, Yong S. Chu, Si Chen, Doğa Gürsoy, Martina Ralle, Barbara Imperiali, Karen N. Allen, Lisa M. Miller
Abstract
We report the application of lanthanide-binding tags (LBTs) for two- and three-dimensional X-ray imaging of individual proteins in cells with a sub-15 nm beam. The method combines encoded LBTs, which are tags of minimal size (ca. 15-20 amino acids) affording high-affinity lanthanide ion binding, and X-ray fluorescence microscopy (XFM). This approach enables visualization of LBT-tagged proteins while simultaneously measuring the elemental distribution in cells at a spatial resolution necessary for visualizing cell membranes and eukaryotic subcellular organelles.