Extended Data Fig. 6: Polyamines establish highly dynamic interactions with the acidic phosphorylation motif of U2 snRNP SF3A3 member.
From: Polyamine-dependent metabolic shielding regulates alternative splicing
a,b, Selected region of the overlaid 1H-1H-TOCSY NMR spectra of the SRRM1 fragment in the absence (black) or presence (from blue to red) of increasing amounts of spermidine (a) or spermine (b) and their quantification. One spectrum recorded along the titration is not shown for the sake of clarity. The arrow indicates the shift in the signal that was used to derive the affinity of the interaction. Chemical shift perturbation of the signal in the spectra along the titration is also shown for spermidine (a) and spermine (b). The line is the fitting to a 1:1 binding model and the constant dissociation is indicated with the standard error. c,d, Selected region of the overlaid 1H-1H-TOCSY NMR spectra of SF3A3 peptide (c) and the SRRM1 fragment (as a negative control) (d) in the absence (black) or presence (from blue to red) of increasing amounts of putrescine and their quantification. One spectrum recorded along the titration is not shown for the sake of clarity. Chemical shift perturbation of the signal in the spectra along the titration is also shown for putrescine. The line is the fitting to a 1:1 binding model and the constant dissociation is indicated with the standard error. e, Initial geometries and potential of mean force (PMF) profiles for the binding free energy calculations of putrescine (left), spermidine (middle) or spermine (right) with SF3A3 by umbrella sampling simulations. Abbreviations: ppm: parts per million, CSP: Chemical shift perturbation, Kd: Dissociation constant.
