Figure 1.
The size of tbParB-D120 assembly derived from the SAXS data. (a) Intensity (I) in arbitrary unit versus momentum transfer q in Å−1 are plotted at 3 different concentrations. The Guinier plot (lnI(q) versus q2, q in Å−1; ) is shown in the inset. These and other graphs presented in this work are prepared using Excel® (Microsoft® corporation). A linear trend-line fitted to the data points is shown in each case. (b) The modified Guinier plot for rod-shaped particle (lnI(q)q versus q2, q in Å−1,
) is shown. (c) The pair-distribution function P(r) versus pair-wise distance r in Å. The pair functions shown here and in the figure 5 were calculated with the following boundary conditions: P(r = 0) = 0 and P(r ≥ Dmax) = 0. (d) The cross-sectional pair-distribution function (PXS(r)) versus pair-wise distance r in Å.
Figure 2.
Hypothetical three-dimensional organizations of the partition assembly. Two topologically alternative scenarios can be proposed: (a) a “DNA inside, protein outside” model or (b) a “DNA outside, protein inside” model. The DNA is shown as black line, proteins are shown as grey beads. These models can be described as composite cylinders for low-resolution solution scattering experiments. Anticipated shapes at the protein and the DNA match-point for both models (as narrower or hollow cylinders) are shown as cartoons (case I–IV). The handedness and scale are arbitrary. We note that solution scattering cannot distinguish between the left- and the right-handed senses.
Figure 3.
The Stuhrmann plot (Rg2 versus Δρ
−1, Δρ in 1010 cm−2, Rg in Å) obtained from the SANS dataset of the tbParB-D120 assembly. The real space radii of gyration derived from the corresponding pair distribution functions were used for the calculation of Stuhrmann plot. A straight-line fitted to the data (R2 = 0.98) is shown in black.
Figure 4.
The comparisons of cross-sectional sizes of the tbParB-D120.
The cross-sectional pair-distribution functions (PXS(r) versus the pair-wise distance r in Å) for the 12.0% (open triangle), 85.5% (grey circle) and 73.5% (black square) D2O datasets suggests a narrowing of the cross-sectional diameter near the DNA-match point. The PXS(r) functions were scaled to an equal maximal height for visualization purpose.
Figure 5.
The modified Guinier plot (ln(q.I(q)) versus q2, I in cm
−1, q in Å−1) of the “73.5% D2O” dataset. The RXS and mass/length of the protein segment were obtained from the slope and the intercept of this plot.