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Figure 4.
Figure 4. The yHst2-Histone H4 Interface(A) Stereo view of
yHst2-histone H4 interactions within the ternary complex.
Hydrogen bonds are indicated with a dashed line. Residues that
mediate van der Waals interactions are also shown.(B) Summary of
yHst2-histone H4 interactions. Hydrogen bonds are indicated with
a dashed line, and van der Waals interactions are indicated with
a half-moon symbol. For clarity, histone H4 side chains that do
no participate in direct protein-peptide interactions are not
shown. The residues highlighted in cyan and red highlight
interactions with acetly-lysine peptide substrate that are
conserved and nonconserved, respectively, with the
protein-peptide interactions observed in the Af2-Sir2/p53
peptide structure.(C) The p53 peptide (purple) from the
Af2-Sir2/p53 peptide structure and the "pseudosubstrate" from
the nascent yHst2 structure (yellow) are overlayed with the
histone H4 peptide (green) onto a surface representation of
yHst2 from the ternary complex. Protein residues that make
conserved interactions between the three substrates are
indicated in blue, and protein residues that mediate variable
interactions are indicated in red.(D) Backbone overlay of
yHst2/NAD^+ (gray) and nascent yHst2 (cyan) homotrimers with the
yHst2/2'-O-acetyl ADP ribose/histone H4 monomer (red). The
ADP-ribose is highlighted in yellow, the histone H4 peptide is
highlighted in green, and the C-terminal domain of nascent yHst2
is highlighted in purple.
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