A Structural Basis for 129Xe Hyper-CEST Signal in TEM-1 β-Lactamase
Genetically encoded (GE) contrast agents detectable by magnetic resonance imaging (MRI) enable non-invasive visualization of gene expression and cell proliferation at virtually unlimited penetration depths. Using hyperpolarized 129Xe in combination with chemical exchange saturation transfer, an MR contrast approach known as hyper-CEST, enables ultrasensitive protein detection and biomolecular imaging. GE MRI contrast agents developed to date include nanoscale proteinaceous gas vesicles as well as the monomeric bacterial proteins TEM-1 β-lactamase (bla) and maltose binding protein (MBP). To improve understanding of hyper-CEST NMR with proteins, we performed structural and computational studies to further characterize the Xe-bla interaction. X-ray crystallography validated themore »