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Figure 3.
Figure 3. Properties of the DgkB Dimer
(A)
Gel-filtration chromatography of DgkB with a Sephadex-200 10/300
GL column. DgkB eluted with a Stokes radius (Rs) of 41 Å
based on calibration of the column with eight protein standards
(left inset). SDS gel electrophoresis (right inset) showed the
presence of a single protein with an apparent subunit molecular
weight of 42 kDa. The molecular weight calculated from the DNA
sequence was 37,333.
(B) Sedimentation velocity analysis of
DgkB. The protein characteristics determined from the velocity
sedimentation experiment are shown as an inset in the figure.
(C) The structure of the DgkB dimer. The green monomer is
the observed molecule in the asymmetric unit shown in Figure 1A,
tilted backward 45°. The sand-colored monomer is generated
by two-fold symmetry. ADP carbons and Mg1 (sphere) are cyan.
(D) The conserved DgkB dimerization interface. Only the
residues involved in salt bridges are shown as sticks. Hydrogen
bonds are indicated with broken lines.
(E) A representative
sequence alignment of the amino-terminal residues in known
bacterial DgkBs involved in dimer formation. Residues
responsible for salt bridges and van der Waals interactions are
indicated with an “x” and black spheres, respectively.
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