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Figure 4.
Figure 4. Hydrogen-Bond Networks Involving Phosphorylation
Site 1
(A) The H-bond network connecting phosphorylation
site 1 and Tyr33-β′ of the E1p-β′ subunit in the wild-type
E1p structure. Ph-loop A is in orange, and Ph-loop B in yellow.
The positions of the three phosphorylation sites are shown as
spheres at the corresponding Cα atom positions. Water molecules
are depicted as small red spheres. H-bonds are indicated by gray
dashed lines.
(B) A similar H-bond network in the
Ser264E-α mutant E1p structure (PDB ID code 2OZL; Seifert et
al., 2007).
(C) A stereo diagram showing absence of the
H-bond network in phospho-S1-E1p containing bound Mn-ThDP. The
phosphoryl group on Ser264-α (site 1) clashes with the side
chain of the neighboring Ser266-α. Van der Waals radii of the
phosphoryl group and side chains of both serine residues are
shown as spheres of red dots.
(D) A stereo figure of the
2Fo-Fc electron density map (contoured at 1σ) at
phosphorylation site 1 with a stick representation of the
refined model.
(E) Average B-factor plots of the wild-type
and phospho-S1-E1p structures. Average B-factors for individual
residues in one of the four nonphosphorylated wild-type E1p-α
subunits (solid line) and one of the two phospho-S1-E1p-α
subunits with the wild-type-like “ordered” Ph-loops (dashed
line) are plotted against the residue number.
The residue
ranges for Ph-loops A and B are indicated on top of the graph.
Each of the three phosphorylation sites and residue Ser266-α
are labeled.
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