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MRI biosensor for protein kinase A encoded by a single synthetic gene
Author(s) -
Airan Raag D.,
BarShir Am,
Liu Guanshu,
Pelled Galit,
McMahon Michael T.,
van Zijl Peter C. M.,
Bulte Jeff W. M.,
Gilad Assaf A.
Publication year - 2012
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.24483
Subject(s) - kinase , phosphorylation , protein kinase a , gene , biosensor , target protein , biology , biochemistry , chemistry , microbiology and biotechnology , computational biology , biophysics
Abstract Purpose: Protein kinases including protein kinase A (PKA) underlie myriad important signaling pathways. The ability to monitor kinase activity in vivo and in real‐time with high spatial resolution in genetically specified cellular populations is a yet unmet need, crucial for understanding complex biological systems as well as for preclinical development and screening of novel therapeutics. Methods: Using the hypothesis that the natural recognition sequences of protein kinases may be detected using chemical exchange saturation transfer magnetic resonance imaging, we designed a genetically encoded biosensor composed of eight tandem repeats of the peptide LRRASLG, a natural target of PKA. Results: This sensor displays a measurable change in chemical exchange saturation transfer signal following phosphorylation by PKA. The natural PKA substrate LRRASLG exhibits a chemical exchange saturation transfer‐magnetic resonance imaging contrast at +1.8 and +3.6 ppm, with a >50% change after phosphorylation with minutes‐scale temporal resolution. Expression of a synthetic gene encoding eight monomers of LRRASLG yielded two peaks at these chemical exchange saturation transfer frequencies. Conclusion: Taken together, these results suggest that this gene may be used to assay PKA levels in a biologically relevant system. Importantly, the design strategy used for this specific sensor may be adapted for a host of clinically interesting protein kinases. Magn Reson Med, 2012. © 2012 Wiley Periodicals, Inc.