Using Genetically Encodable Self-Assembling Gd(III) Spin Labels to Make In-cell Nanometric Distance Measurements

MASCALI FC; CHING VHY; RASIA RM; UN S; TABARES LC

Angewandte Chemie

WILEY-V C H VERLAG GMBH

Año: 2016

1433-7851

Double electron-electron resonance (DEER) is capable of studying the structure of a protein in its native cellular environment. Until now, this has required isolation, in vitro labeling and reintroduction of the protein back into the cells. We describe a completely biosynthetic approach that avoids these steps. It exploits genetically encodable Lanthanide Binding Tags (LBT) to form self-assembling Gd(III) metal-based spin-labels and allows for direct in-cell measurements. This approach is demonstrated using two LBTs encoded onto the ends of a 3-helix bundle expressed in E. coli grown on Gd(III) supplemented media. DEER measurements directly on these cells produced readily detectable time-traces from which the distance between the Gd(III) labels could be determined. This work is the first to use biosynthetic self-assembling metal spin-labels for non-disruptive in-cell structure measurements.