SANS and SAXS analyses. (A) SANS profiles of EcoR124I. The
left panel shows the scattering data, and the
right panel shows the pair distribution functions,
p(r). (Gray) Protonated EcoR124I in 0%
D2O; (blue) MTase core in situ within the RM enzyme (deuterated
HsdR and protonated MTase measured in 100% D2O); (red) the two HsdR
in situ in the RM enzyme (deuterated HsdR and protonated MTase measured in 40%
D2O). (B) SAXS profiles of EcoR124I (black) and
EcoKI (green). The panel on the left shows the scattering
data, and the right panel shows the pair distribution
functions, p(r). In both A
and B, the solid lines in the scattering data represent the
fits from the corresponding back-transformed distance distribution functions,
p(r), in the panel on the
right. (C) Multiphase ab initio modeling
showing the location of the MTase core (blue) and the HsdR (red), superimposed
on the EM map of EcoR124I from Figure 1B
(gray). The panel on the right shows a 90° rotation
about the long axis in the left panel. Data on the assembly of
the EcoR124I enzyme can be found in Supplemental Figure S3.