The Interaction of Vinculin with Actin
Figure 9
Capping of F-actin by vinculin in its closed conformation and open II conformation.
(A) The surface of Vt (orange) likely to cap F-actin is normally occluded by vinculin head domains (black). D1 of the vinculin head is shown in green and the flexible loop region is shown in yellow. Subunit n of actin is shown in blue, and subunit n-2 of actin is shown in red. Simulation with full-length vinculin in its closed conformation oriented towards S1 and S3 and with the same orientation as used for binding of the occluded surface of Vt to S1 and S3 resulted in formation of a small interface between Vt and the barbed-end of actin (inset). (B) The occlusion of Vt from F-actin can be removed after a potential conformational change. After 15 ns of simulation with this full-length vinculin structure in an open II conformation an interface has formed between Vt and F-actin (inset). Several interactions stabilize this interface: E932 with K291, R935 and K889 with D288, N943 with D286, E883 with R147, R925 with E167, K956 with T351, K952 with Q354, and R945 with Q349.