A Genetically Encoded β-Lactamase Reporter for Ultrasensitive (129) Xe NMR in Mammalian Cells.
Molecular imaging holds considerable promise for elucidating biological processes in normal physiology as well as disease states, but requires noninvasive methods for identifying analytes at sub-micromolar concentrations. Particularly useful are genetically encoded, single-protein reporters that harness the power of molecular biology to visualize specific molecular processes, but such reporters have been conspicuously lacking for in vivo magnetic resonance imaging (MRI). Herein, we report TEM-1 β-lactamase (bla) as a single-protein reporter for hyperpolarized (HP) (129) Xe NMR, with significant saturation contrast at 0.1 μm. Xenon chemical exchange saturation transfer (CEST) interactions with the primary allosteric site in bla give rise to a unique saturation peak at 255 ppm, well removed (≈60 ppm downfield) from the (129) Xe-H2 O peak. Useful saturation contrast was also observed for bla expressed in bacterial cells and mammalian cells.
Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, PA, 19104-6323, USA.
Yanfei
0000-0002-9358-4759
Y
Wang
Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, PA, 19104-6323, USA.
Benjamin W
0000-0003-3333-5053
BW
Roose
Institute for Computational Molecular Science, College of Science and Technology, Temple University, 1925 N. 12th Street, Philadelphia, PA, 19122, USA.
Eugene J
EJ
Palovcak
Institute for Computational Molecular Science, College of Science and Technology, Temple University, 1925 N. 12th Street, Philadelphia, PA, 19122, USA.
Vincenzo
V
Carnevale
Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, PA, 19104-6323, USA. ivandmo@sas.upenn.edu.
Ivan J
0000-0001-7162-1347
IJ
Dmochowski
D057809:HEK293 Cells; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D057054:Molecular Imaging; D014978:Xenon / Q000737:chemistry / Q000378:metabolism*; D014979:Xenon Isotopes; D001618:beta-Lactamases / Q000737:chemistry / Q000378:metabolism*
D014979:Xenon Isotopes; D014978:Xenon; D001618:beta-Lactamases
NMR reporter genes; contrast agents; molecular imaging; protein biophysics; supramolecular chemistry