|
Figure 2.
Figure 2. Crosslinking Bovine Arp2/3 Complex Crystals with
Glutaraldehyde Increases Order in Subdomain 1 of Arp2
(A)
Final 3σ F[o] − F[c] electron density map and Cα trace of
modeled regions of Arp2 in uncrosslinked bovine Arp2/3
complex-ATP-Mg^2+ cocrystals (2P9S). The map shows little
density for subdomains 1 and 2.
(B) Final 3σ F[o] − F[c]
omit map and Cσ trace of modeled regions of Arp2 in bovine
Arp2/3 complex-ATP-Ca^2+ cocrystals treated with glutaraldehyde
(2P9K). The newly modeled regions were not included in the map
calculation.
(C) Steric hindrance with Arp3 may prevent
Arp2 from closing in the inactive complex. Cα traces show Arp3
(cyan) and Arp2 (blue) from the structure of crosslinked
ADP-Arp2/3 complex (2P9I) with the addition of a model of four
disordered residues at the end of the αK/β15 loop of Arp3
(orange). Actin (red) is overlaid onto Arp2 to show potential
clashes (red arrows) of subdomain 2 with the αI/αJ loop and
the αK/β15 loop of Arp3. The yellow Cα trace (highlighted
with arrow) shows how αK is connected to β15 in actin. The
αK/β15 insert in Arp3 makes the αK helix three turns longer
in Arp3 than actin.
|
