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Figure 2.
Fig. 2. The contacts made by the N segment, and in particular
by Hyp564, are central to the binding of HIF-1  to pVHL.
(A) Closeup view of the HIF-1 N
segment-pVHL contacts. The side chains of HIF-1 and pVHL
are colored in light blue and yellow, respectively. The
backbones of HIF-1 and pVHL
are in medium blue and red, respectively. The dotted lines
indicate hydrogen bonds between the Gln67 O  [1], Tyr98
O  , His110 NH,
and His110 CO groups of pVHL, and the Leu562 NH, Hyp564 CO,
Tyr565 NH, and Tyr565 CO groups of HIF-1 . In pVHL,
only the structural elements that make up the HIF-1 binding
site are shown for clarity. (B) Surface representation of pVHL
colored according to the degree of conservation in the pVHL
orthologs in Fig. 1B. Yellow indicates identity in five
orthologs (labeled residues), light green in four, and dark
green in three. The HIF-1 side
chains are in light blue, and the backbone is in medium blue.
The N segment is in an orientation similar to that of (A). The
approximate boundaries of the N and C segments and of the bulge
are indicated. (C) Closeup view of the bulge and the C-segment
area of the HIF-1 peptide-pVHL
complex. The 567 P-M-D-D 571 bulge sequence does not contact
pVHL, but forms an intramolecular  -turn
hydrogen bond (CO of Pro567 and NH of Asp569). The Asp570 side
chain of HIF-1 is omitted
for clarity.
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