Extended Data Fig. 6: Enzymatic activity and oligomeric state of BsIMPDH-WT and CBS domain variants.
From: Diadenosine tetraphosphate regulates biosynthesis of GTP in Bacillus subtilis
a. Representative distributions of tetrameric and octameric BsIMPDH species for BsIMPDH-WT in the absence of IMP and NAD+ substrates and in dependence of Ap4A or ATP concentration. b-e. Representative distributions of tetrameric and octameric BsIMPDH species of b. BsIMPDH-WT, c. BsIMPDH-K202A, d. BsIMPDH-R141A/R144A, and e. BsIMPDH-ΔCBS, all in the presence of IMP and NAD+ substrates and in dependence of Ap4A or ATP concentration. f. Representative distributions of tetrameric and octameric BsIMPDH species for BsIMPDH-WT in the presence of IMP and NAD+ substrates and in dependence of the indicated adenosine nucleotides or ApnA and ApnG dinucleotides added. In a-f, the numbers in the diagrams reflect the molecular weight of the observed oligomeric species (mean and SD), the number of observed molecules for either species and their percentage of all observed molecules in the sample. g. Effect of 10 µM Ap4A or 2 mM ATP on the enzyme-kinetic behavior of BsIMPDH-WT and CBS domain variants K202A, R141A/R144A and ΔCBS for conversion of the IMP substrate into XMP. Individual data points of n = 2 replicates are shown, and parameters of the fits are given in Extended Data Fig. 2c. h. Correlation between observed fraction of IMPDH monomers in oligomeric state and the apparent Vmax of IMPDH activity. Linear regression was performed either with values for BsIMPDH WT only (red trace) or all depicted values including WT and variants (blue trace). Red and blue numbers denote values for the fraction and Vmax at the intersects with the x-axis and y-axis, respectively.
