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Figure 2.
Figure 2. Pro-Ser Step-Containing Peptide Binding by L3MBTL1
Pocket 1
(A) Domain architecture of the L3MBTL1 constructs
used for structural and functional study in this figure. For the
L3MBTL1-H3.3 construct, a Gly-Gly-Gly linker was used to
separate L3MBTL1 and the covalently attached histone
3.3[28–34] segment.
(B) Insertion of proline into a
shallow cavity of symmetry-related L3MBTL1 pocket 1 in the
Kme2-L3MBTL1 complex is shown. The Pro ring is sandwiched within
the narrow walls at the base of the pocket. The interior parts
of the surface are colored in gray, and exterior parts are
colored by their electrostatic potential as described for Figure
1C. The Pro ligand is shown in the dotted van der Waals radius
representation. The “EPS” peptide segment is shown, with
part of the Ser omitted from the drawing for clarity.
(C)
Relative positioning of PS step containing C-terminal L3MBTL1
segment in pocket 1 and Kme2 in pocket 2 on the same L3MBTL1
surface in the Kme2-L3MBTL1 complex.
(D) Stereo view of the
PS step containing H3.3 SAPSTGG segment with its Pro ring
inserted into pocket 1 of the Kme2-L3MBTL1-H3.3[28–34]
complex. Key residues participating in pocket formation are
shown in stick representation (cyan) with main-chain atoms
omitted for clarity. Water molecules are shown as small red
spheres and hydrogen bonds indicated by dashed red lines.
(E) Stereo view of the relative positioning of PS step
containing H3.3 SAPSTGG segment in pocket 1 and Kme2 in pocket 2
on the same L3MBTL1 surface in the Kme2- L3MBTL1-H3.3[28–34]
complex. Note that the type II β-turn formed at the “APST”
motif in pocket 1 helps to direct the C-terminal GG segment of
H3.3 toward the Kme2-bound pocket 2. Water molecules are shown
as small red spheres and hydrogen bonds indicated by dashed red
lines.
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