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Figure 4.
Figure 4. Peptide Binding Interactions(A) Schematic drawing
of the contacts between the BCL6 BTB domain and the “yellow”
SMRT chain (colors as in Figure 3A). Nearly identical contacts
are observed in the other contact surface.(B) Highlight of the
interactions between SMRT 1427–1430 and the BCL6 BTB
domain.(C) Interactions of SMRT 1424–1426 with the BCL6 BTB
domain.(D) To view the interactions between region 1414–1423
of the SMRT-BBD peptide and BTB β1′, the BCL6 helix α6 (red
chain) has been made transparent.(E) Superposition of the two
crystallographically independent SMRT peptides from the complex,
with carbons shown in yellow and green as in Figure 3. The six
waters from each site that participate in the bridging SMRT/BCL6
interactions are indicated as yellow or green spheres.(F)
Mutations in the BCL6 BTB peptide binding pocket reduce the
affinity for the SMRT peptide. His-tagged Trx-(SMRT-BBD) was
mixed with three different forms of the BCL6 BTB domain, and the
load (“L”), flow through (“FT”), wash (“W”), and
elute (“E”) fractions from each copurification trial were
analyzed by SDS-PAGE.
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