TY - JOUR
T1 - A novel mechanism of actin filament processive capping by formin
T2 - Solution of the rotation paradox
AU - Shemesh, Tom
AU - Otomo, Takanori
AU - Rosen, Michael K.
AU - Bershadsky, Alexander D.
AU - Kozlov, Michael M.
PY - 2005/9/12
Y1 - 2005/9/12
N2 - The FH2 domains of formin family proteins act as processive cappers of actin filaments. Previously suggested stair-stepping mechanisms of processive capping imply that a formin cap rotates persistently in one direction with respect to the filament. This challenges the formin-mediated mechanism of intracellular cable formation. We suggest a novel scenario of processive capping that is driven by developing and relaxing torsion elastic stresses. Based on the recently discovered crystal structure of an FH2-actin complex, we propose a second mode of processive capping - the screw mode. Within the screw mode, the formin dimer rotates with respect to the actin filament in the direction opposite to that generated by the stair-stepping mode so that a combination of the two modes prevents persistent torsion strain accumulation. We determine an optimal regime of processive capping, whose essence is a periodic switch between the stair-stepping and screw modes. In this regime, elastic energy does not exceed feasible values, and supercoiling of actin filaments is prevented.
AB - The FH2 domains of formin family proteins act as processive cappers of actin filaments. Previously suggested stair-stepping mechanisms of processive capping imply that a formin cap rotates persistently in one direction with respect to the filament. This challenges the formin-mediated mechanism of intracellular cable formation. We suggest a novel scenario of processive capping that is driven by developing and relaxing torsion elastic stresses. Based on the recently discovered crystal structure of an FH2-actin complex, we propose a second mode of processive capping - the screw mode. Within the screw mode, the formin dimer rotates with respect to the actin filament in the direction opposite to that generated by the stair-stepping mode so that a combination of the two modes prevents persistent torsion strain accumulation. We determine an optimal regime of processive capping, whose essence is a periodic switch between the stair-stepping and screw modes. In this regime, elastic energy does not exceed feasible values, and supercoiling of actin filaments is prevented.
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U2 - 10.1083/jcb.200504156
DO - 10.1083/jcb.200504156
M3 - Article
C2 - 16157699
AN - SCOPUS:24944560068
SN - 0021-9525
VL - 170
SP - 889
EP - 893
JO - Journal of Cell Biology
JF - Journal of Cell Biology
IS - 6
ER -