Accurate Measurement of Residual Dipolar Couplings in Large RNAs by Variable Flip Angle NMR.
Jan MarchantAdriaan BaxMichael F SummersPublished in: Journal of the American Chemical Society (2018)
NMR approaches using nucleotide-specific deuterium labeling schemes have enabled structural studies of biologically relevant RNAs of increasing size and complexity. Although local structure is well-determined using these methods, definition of global structural features, including relative orientations of independent helices, remains a challenge. Residual dipolar couplings, a potential source of orientation information, have not been obtainable for large RNAs due to poor sensitivity resulting from rapid heteronuclear signal decay. Here we report a novel multiple quantum NMR method for RDC determination that employs flip angle variation rather than a coupling evolution period. The accuracy of the method and its utility for establishing interhelical orientations are demonstrated for a 36-nucleotide RNA, for which comparative data could be obtained. Applied to a 78 kDa Rev response element from the HIV-1 virus, which has an effective rotational correlation time of ca. 160 ns, the method yields sensitivity gains of an order of magnitude or greater over existing approaches. Solution-state access to structural organization in RNAs of at least 230 nucleotides is now possible.
Keyphrases
- high resolution
- solid state
- magnetic resonance
- human immunodeficiency virus
- antiretroviral therapy
- hiv infected
- hepatitis c virus
- mass spectrometry
- hiv positive
- hiv aids
- electronic health record
- hiv testing
- healthcare
- heat shock protein
- machine learning
- dengue virus
- risk assessment
- room temperature
- human health
- big data