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Figure 5.
Figure 5. Common Binding Mode for MutSα Substrates
(A)
Interactions between a G•T mispair and an adjacent base pair
with MSH6 domain 1 (shown as sticks under a semitransparent
electrostatic surface).
(B) Protein-mispair contacts in a
MutSα/G•dU/DNA complex. Putative hydrogen bonds are shown as
dashed lines. Interacting residues (defined with LIGPLOT
[Wallace et al., 1995]) are labeled. Orientation is rotated  vert,
similar 90° from (A).
(C) Protein mispair contacts in a
MutSα/O^6-methyl-guanine/DNA complex, colored, labeled, and
oriented as in (B).
(D) Interactions between a single base
T insert substrate (cyan carbons) or a G•T mispair (green
carbons) substrate and MSH6 domain 1 (blue surface). Hydrogen
bonds are shown as dashed lines. Orientation is approximately
the same as (A).
(E) Protein-DNA interactions in the
MutSα-DNA complex. Amino acids that make hydrogen bonding (red
lines) or van der Waals interactions (gray lines) are indicated
with blue text (MSH6) or red text (MSH2). Dashed lines group the
amino acids by protein domain as indicated. Interactions were
classified by using Probe (Word et al., 1999).
(F)
Structures with G•T (red), T insert (green) were superimposed
on domain 1 of MSH6. DNAs from both complexes are shown as
sticks, and backbone traces of MSH2 are shown as ribbons and
surfaces. The arrow indicates the movement of domains 4 and 3 of
MSH2 in the insert structure that compensates for the slight
change in the DNA substrate register.
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